Category Exploring the Universe

What’s space weather?

Ever wondered about the weather in space? Before that, let’s think about what dictates the weather on our planet. The Sun, which is our source of energy, plays a titular role in governing the weather on Earth. And so does it create the weather in space! The activities on the Sun’s surface can lead to a type of weather in space and this is called space weather.

Space weather is dependent on activities and changes on the Sun’s surface such as coronal mass ejections (eruptions of plasma and magnetic field structures) and solar flares (sudden bursts of radiation). We are shielded from these bursts of radiation and energy by Earth’s magnetosphere, ionosphere, and atmosphere.

Impact of space weather

The Sun is some 93 million miles away from our Earth. Yet, space weather can affect us and the solar system. The electric power distribution grids, global satellite communication, and navigation systems are all susceptible to conditions in space that are impacted by the Sun.

Space weather can damage satellites, affect astronauts and even cause blackouts on Earth. Such incidents are rare but they have happened before.

CME, solar flare

When a CME reaches Earth, it leads to a geomagnetic storm. This can disrupt services, damage power grids and cause blackouts.

For instance, back in 1989, a powerful geomagnetic storm led to a major power blackout in Canada. As a result, around 6 million people were left in the dark for about 9 hours.

Solar flares can also result in disruption of services. The strongest and most intense geomagnetic storm ever recorded occurred in 1859. This was caused by a solar flare. Called the “Carrington Event and named after England’s solar astronomer Richard Carrington who observed the activity through his telescope, the geomagnetic storm caused damage, disrupting the telegraph system on Earth. It also led to the aurorae, a result of geomagnetic activity, being visible in regions such as Cuba and Hawaii.

While telegraph networks are a thing of the past, our communications system and technologies can still be impacted by space weather. Even as most of the charged particles released by the Sun get shielded away due to Earth’s magnetic field, sometimes space weather can affect us. We need to track the activities on the Sun’s surface and understand them to protect the people and systems.

Any warning regarding bad space weather can help scientists send alerts and lessen the damage caused by it. Space agencies have observatories monitoring the Sun and detecting solar storms. These help in mitigating the effect of bad space weather.

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Naming planetary objects?

On August 23, India celebrated a technological triumph when Chandrayaan-3 landed near the Moon’s South Pole at 6:04 p.m. Since then, there has been a discussion on the naming of the landing spot, which Prime Minister Narendra Modi has termed Shiv Shakti.

Do you know how are planetary objects are usually named?

International Astronomical Union             

The International Astronomical Union (IAU), founded in 1919, is responsible for assigning names to celestial bodies and surface features on them. In the IAU, there are numerous Working Groups that suggest the names of astronomical objects and features.

In 1982, the United Nations, at its ‘Fourth Conference on the Standardisation of Geographical Names held in Geneva, recognised the role of the IAU by adopting its resolution on extraterrestrial feature names.

Key rules

The IAU has set some rules for naming planetary objects. Some of the most important rules are -the names should be simple, clear, and unambiguous; there should not be duplication of names; no names having political, military or religious significance may be used, except for names of political figures prior to the 19th Century; and if a name of a person is suggested, then he/she must have been deceased for at least three years, before a proposal may be submitted.

Process of naming

When the first images of the surface of a planet or satellite are obtained, themes for naming features are chosen and names of a few important features are proposed, usually by members of the appropriate IAU Working Group. However, there is no guarantee that the name will be accepted.

Names reviewed by an IAU Working Group are submitted by the group’s chairperson to the Working Group for Planetary System Nomenclature (WGPSN). After this, the members of the WGPSN vote on the names.

The names approved by the WGPSN members are considered as official IAU nomenclature and can be used on maps and in publications. The approved names are then entered into the Gazetteer of Planetary Nomenclature, and posted on the website of IAU.

Objections

If there are any objections to the proposed names, an application has to be sent to the IAU general secretary within three months from the time the name was placed on the website. The general secretary will make a recommendation to the WGPSN Chair as to whether or not the approved name(s) should be reconsidered.

 In 1966, the Outer Space Treaty was formed by the United Nations Office for Outer Space Affairs to set rules for international space law. One of the key aspects of this treaty was that the outer space, including the moon and other celestial bodies, shall be free for exploration and use by all states without discrimination of any kind, on a basis of equality and in accordance with international law, and there shall be free access to all areas of celestial bodies.

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Are Saturn’s rings actually young?

The rings of Satum have fascinated and captivated humankind for over 400 years. It was in 1610 that Italian astronomer Galileo Galilei first observed these features through a telescope, though he had no idea what they were.

While our understanding of Saturn’s rings has matured over these four centuries, the age of these rings haven’t been determined precisely yet. The assumption that the rings likely formed at the same time as Satum draws flak as the rings are sparkling clean when compared to the planet.

A new study at the University of Colorado Boulder has provided the strongest evidence so far that the rings of Saturn are remarkably young. The research, published in May in the journal Science Advances, places the age of Saturn’s rings at around 400 million years old. When we compare this with Saturn itself, which is 4.5 billion years old, the rings are really young.

Studying dust                                                                        

The researchers arrived at this number by studying dust. By studying how rapidly the layer of dust built up on Saturn’s rings, they set out to put a date on it. It was, however, not an easy process.

The Cassini spacecraft provided an opportunity by arriving at Saturn in 2004 and collecting data until it intentionally crashed into the planet’s atmosphere in 2017. The Cosmic Dust Analyzer, which was shaped a little bit like a bucket and was aboard this spacecraft, scooped up small particles as the spacecraft whizzed by.

Just 163 grains

The researchers were able to collect just 163 grains of dust that had originated from beyond Saturn’s close neighbourhood during these 13 years. This quantity. however, was enough to make their calculations, placing the age of Saturn’s rings at a little less than 400 million years.

With this, we now know approximately how old Saturn’s rings are and that they are a relatively new phenomena in cosmic terms. With a previous study suggesting that Saturn’s rings could entirely disappear in another 100 million years, questions pertaining to how these rings were initially formed and why these short-lived, dynamic rings can be seen just now still remain.

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What are the Astronomers, who helped enhance our understanding of the cosmos?

We have always been looking up, peering into the sky, trying to find answers to the many questions about the universe. Many astronomers have tried to unravel the mysteries of the universe. From believing that Earth was flat and the planets revolved around it, we have come a long way. Let’s take a look at some of history’s greatest astronomers who helped enhance our understanding of the Cosmos.

From believing that the Earth was flat and the planets revolved around it, we have come a long way.Some 2000 years ago, when it was widely believed that the world was flat, Greek mathematician and astronomer Eratosthenes (276 BC-194 BC) calculated the Earth’s circumference. In those days, the very act of coming up with scientific thoughts which were at odds with the ones in existence was not encouraged. The theory that the Earth revolved around the Sun was itself considered heretical by the religious and after a trial, Italian astronomer Galileo Galilei was kept under house arrest until his death. Polish astronomer Nicolaus Copernicus didn’t publish his magnum opus “De revolutions orbium coelestium” (On the Revolutions of the Heavenly Spheres) until he was on his deathbed. Let’s take a look at some of history’s greatest astronomers who threw new light on the cosmos.

CLAUDIUS PTOLEMY (AD 100-AD 170)

 Astronomer and mathematician Claudius Ptolemy authored several scientific teas and is noted for his Ptolemaic system. It was a geocentric (Earth-centred) model of the universe, where the sun, stars, and other planets revolved around Earth. This model was used for a long period, for over 1200 years, until the heliocentric view of the solar system was established. Although his model of the universe was wrong, his work and the scientific texts he authored helped astronomers make predictions of planetary positions and solar and lunar eclipses. “The Almagest, a comprehensive treatise on the movements of the stars and planets, was published in the 2nd Century. It is divided into 13 books. This manual served as the basic guide for Islamic and European astronomers. He also catalogued 48 constellations. 

NICOLAUS COPERNICUS (1473-1543)

 Nicolaus Copernicus changed the way scientists viewed the solar system. Back in the 16th Century, he came up with a model of the solar system where the Earth revolved around the Sun: it was the revolutionary heliocentric model. He removed Earth from the centre of the universe and replaced it with the Sun! He also didn’t believe in the Ptolemaic model of the planets travelling in circular orbits around the Earth. He also explained the retrograde motion of the planets (retrograde motion is when planets appear to move in the opposite direction of the stars). When the Polish astronomer was 70, he published his book “De Revolutions Orbium Coelestium” (“On the Revolutions of the Heavenly Spheres”), on his deathbed. It took over a century for his idea to gain credence.

GALILEO GALILEI (1564-1642)

Optical astronomy began with Galileo Galilei. Born in Italy, Galilei is credited with creating the optical telescope. In fact, what he did was improve upon the existing models. He came up with his first telescope in 1609, modelling it after the telescopes produced in other parts of Europe. But here is the catch. Those telescopes could magnify objects only three times. Galileo came up with a telescope that could magnify objects 20 times. He then pointed it towards the sky, coming up with the greatest discoveries ever. He discovered the four primary moons of Jupiter which are referred to as the Galilean moons. He also discovered the rings of Saturn. Even though the theory of Earth circling the Sun had been around since Copernicus’ time, when Galileo defended it, he was kept under house arrest till the end of his lifetime.

JOHANNES KEPLER (1571-1630)

Danish astronomer Johannes Kepler modified the Copernican view of the solar system and changed it radically. He deduced that the planets travelled in elliptical orbits, one of the most revolutionary ideas at the time, replacing Copernicus view that they travelled in circular objects. He came up with three revolutionary laws involving the motions of planets these three laws make him a towering figure in astronomy. Kepler also observed a supernova in 1604. It is now called Kepler’s Nova.

EDMOND HALLEY (1656-1742)

“Halley’s comet is perhaps a term you would have heard quite often. English astronomer Edmond Halley never saw the comet named after him. Officially called 1P/Halley, Halley’s  comet  is a periodic comet that passes by the Earth once every 76 years (roughly). This famed comet will return in 2061. It was Halley’s mathematical prediction of the comet’s return that made him a towering figure among the list of astronomers. He said that the comet that appeared in 1456, 1531, 1607, and 1682 were all the same and that it would return in 1758. Halley was never around to witness this, but the world saw the comet and its return. The comet was later named in his honour. One of the earliest catalogues of the southern sky was also produced by Halley. In 1676, he sailed to the island St. Helena, South Atlantic Ocean. There he spent a year measuring the position of stars and came up with the first catalogue of the southern sky! Seen here is a painting of the astronomer. 

WILLIAM HERSCHEL (1750-1848)

Musician-tumed astronomer William Herschel started exploring the skies with his sister Caroline quite late in his career but eventually, he compiled a catalogue of 2.500 celestial objects The German astronomer discoverest the planet Uranus and several moons of other planets it was during his mid 30s that he startet looking up and exploring the cosmos In 1759. Herschel left Germany and moved to England where he started teaching music When Herschels interest in astronomy grew, rented a telescope. He then went ahead and built himself a large telescope to watch the celestial bodies. His sister Caroline assisted him until Herschel’s death and also became the first woman to discover a comet. She eventually discovered eight of them. When Herschel found a small object in the night sky, he explored further and found out that it was a planet. The Uranus was thus discovered. He was knighted by the monarch after the discovery and was appointed the court astronomer. Following this he gave up his music career and devoted himself to the skies. He found the moons of Uranus and Saturn Craters on the moon. Mars and Mimas (Saturn’s moon) are named after the astronomer.

ANNIE JUMP CANNON (1863-1941)

Known as the “census taker of the sky, American astronomer Annie Jump Cannon made stellar contributions to the field of astronomy. She classified around 3,50,000  stars manually. At a time when gender representation in astronomy was  skewed. Cannon with her impeccable contributions inspired many women to pursue astronomy. During that time, stars were classified alphabetically, from A to Q. based on their temperatures. She built a new classification system with ten categories and forever changed the way scientists classified stars by developing the Harvard system which is in use even today.

CARL SAGAN (1934-1996)

American astronomer Carl Sagan was not just a science poster boy but he was one of the most influential voices in the scientific  realm  who  made the cosmos a subject of interest for the masses. Sagan played a huge role in in the American space program. He popularised astronomy and through his talks and books motivated many to become sky watchers. He also founded the Planetary Society, a non-profit that is focussed on advancing space science and exploration. He was a professor of astronomy and space sciences and director of the Laboratory for Planetary Studies at Cornell University. His contributions include explaining the high temperatures of Venus and the seasonal changes on Mars. His book “Cosmos” is a bestseller that was also turned into a television show (hosted by Sagan) which was watched by a billion people in 60 countries. He also wrote a science fiction novel “Contact” which was adapted to the screen.

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What is the significance of Artemis Accord for India?

India’s aspirations in the outer space and acceptance of the Artemis Accords have affirmed the country’s interest in building a greater relationship with the National Aeronautics and Space Administration (NASA) and its partners. As the space community lauds India’s acceptance of the Artemis Accords, let us know more about it.

Artemis Accords

The Artemis Accords are part of the Artemis programme, which is a mega-initiative by NASA with the aim to land the first woman and first person of colour on the Moon, make new scientific discoveries, and explore more of the lunar surface. Artemis is the name of the goddess of the Moon in Greek mythology and also the twin sister of Apollo.

The Artemis Accords were established in 2020 by NASA, the U.S., and seven other founding member nations – Australia, Canada, Italy, Japan, Luxembourg, UAE, and the U.K. This June 21, India became the 27th country to sign the Artemis Accords.

The Artemis Accords are a set of non-binding guidelines designed to guide civil space exploration and use in the 21st Century. It is a NASA-led effort to return humans to the moon by 2025, with the ultimate goal of expanding space exploration to Mars and beyond.

The Artemis Accords reinforce and implement key obligations in the 1967 Outer Space Treaty (which provided the basic framework for international space law). The accords also affirm the importance of the Rescue and Return Agreement opened in 1968, which emphasises the responsibility of nations to safely return astronauts and equipment to Earth.

Besides, the accords emphasise the need to preserve historically significant human or robotics landing sites, artefacts, spacecraft, and other evidence of activity on celestial bodies.

Outer Space Treaty

The Outer Space Treaty is an international treaty binding the parties to use outer space only for peaceful purposes. The treaty was enforced on October 10, 1967, after being ratified by the U.S., then Soviet Union, the U.K.. and several other countries.

The treaty prohibits countries from placing nuclear arms or other weapons of mass destruction in orbit, on the Moon, or on other bodies in space. Also, no country can claim sovereignty over the Moon or other celestial bodies. The countries are liable for any damage caused by objects launched into space from their territory.

India and the Artemis Accords

India’s Indian Space Research Organisation (ISRO) and NASA had been working together in several lunar missions. However, the cooperation was limited to sharing knowledge. With the signing of the Accords, India and the US will share data, technology, and resources, and work together in ensuring the safety and sustainability of exploring the Moon.

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When did Voyager 2 achieve its closest approach to Jupiter?

On July 9, 1979, Voyager 2 made its closest approach to the largest planet in our solar system. Now in interstellar space. Voyager 2 altered some of our ideas about the Jovian system.

The Voyager probes are: humanity’s longest running spacecraft as they have been flying since 1977 Both Voyager 2 and Voyager 1 are now in interstellar space, and though their power sources are gradually fading, they are still operational as of now.

It might seem counter-intuitive, but Voyager 2 was the first to be launched on August 20, 1977-about two weeks before the launch of Voyager 1. Both spacecraft were equipped with an extensive array of instruments to gather data. about the outer planets and their systems, in addition to carrying a slow-scan colour TV camera capable of taking images of the planets and their moons.

Based on Mariners

The design of the Voyagers was based on the Mariners and they were even known as Mariner 11 and Mariner 12 until March 7. 1977. It was NASA administrator James Fletcher who announced that the spacecraft would be renamed Younger. The Voyagers are powered by three plutonium dioxide radioisotope thermoelectric generators (RTGS) mounted at the end of a boom (a long metal beam extending from the spacecraft and serving as a structure subsystem).

Even though Voyager 1 was launched a little later, it reached Jupiter first in 1979 as it took a trajectory that put it on a faster path. Voyager 2 began transmitting images of Jupiter from April 24, 1979 for time-lapse movies of atmospheric circulation. For the next three-and-a-half months, until August 5 of that year, the probe continued to click images and collect data. A total of 17,000 images of Jupiter and its system were sent back to the Earth.

The spectacular images of the Jovian system included those of its moons Callisto, Europa, and Ganymede. While Voyager 2 flew by Callisto and Europa at about half the distance between the Earth and its moon, it made an even closer approach to Ganymede.

Ocean worlds

The combined cameras of the two Voyager probes, in fact. covered at least four-fifths of the surfaces of Ganymede and Callisto. This enabled the mapping out of these moons to a resolution of about 5 km.

Voyager 2’s work, along with observations made before and after, also helped scientists reveal that each of these moons were indeed an ocean world.

On July 9, 1979, the probe made its closest approach to Jupiter. Voyager 2 came within 6,45,000 km from the planet’s surface, less than twice the distance between Earth and its moon. It detected many significant atmospheric changes, including a drift in the Great Red Spot in addition to changes in its shape and colours.

Voyager 2 also relayed photographs of other moons like lo and Amalthea. It even discovered a Jovian satellite, later called Adrastea, and revealed a third component to the planet’s rings. The thin rings surrounding Jupiter, as had been seen by Voyager 1 as well, were confirmed by images looking back at the giant planet as the spacecraft departed for Saturn. As the probe used the gravity assist technique, Jupiter served as a springboard for Voyager 2 to get to Saturn.

Studies all four giant planets

 Four decades after its closest approach to Jupiter, Voyager 2 successfully fired up its trajectory correction manoeuvre thrusters on July 8, 2019. These thrusters, which had themselves last been used only in November 1989 during Voyager 2’s encounter with Neptune, will be used to control the pointing of the spacecraft in interstellar space.

In those 40 years, Voyager 2 had achieved flybys of Saturn (1981), Uranus (1986), and Neptune (1989), thereby becoming the only spacecraft to study all four giant planets of the solar system at close range. Having entered interstellar space on December 10, 2018, Voyager 2 is now over 132 AU (astronomical unit-distance between Earth and the sun) away from the Earth, still relaying back data from unexplored regions deep in space.

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Membrane mirrors for large space-based telescopes?

Researches create lightweight flexible mirrors that can be rolled up during launch and reshaped precisely after deployment.

Mirrors are a significant part of telescopes. When it comes to space telescopes, which have complicated procedures for launching and deploying, the primary mirrors add considerable heft, contributing to packaging difficulties.

Researchers have now come up with a novel way of producing and shaping large, high-quality mirrors. These mirrors are not only thinner than the primary mirrors usually employed in space-based telescopes, but are also flexible enough to be rolled up and stored inside a launch vehicle.

Parabolic membrane mirror

The successful fabrication of such parabolic membrane mirror prototypes up to 30 cm in diameter have been reported in the Optica Publishing Group journal Applied Optics in April. Researchers not only believe that these mirrors could be scaled up to the sizes required in future space telescopes, but have also developed a heat-based method to correct imperfections that will occur during the unfolding process.

Using a chemical vapour deposition process that is commonly used to apply coatings (like the ones that make electronics water-resistant), a parabolic membrane mirror was created for the first time. The mirror was built with the optical qualities required for use in telescopes. A rotating container with a small amount of liquid was added to the inside of a vacuum chamber in order to create the exact shape necessary for a telescope mirror. The liquid forms a perfect parabolic shape onto which a polymer can grow during chemical vapour deposition, forming the mirror base. A reflective metal layer is applied to the top when the polymer is thick enough, and the liquid is then washed away.

Thermal technique

The researchers tested their technique by building a 30-cm-diameter membrane mirror in a vacuum deposition chamber. While the thin and lightweight mirror thus constructed can be folded during the trip to space, it would be nearly impossible to get it into perfect parabolic shape after unpacking. The researchers were able to show that their thermal radiative adaptive shaping method worked well to reshape the membrane mirror.

Future research is aimed at applying more sophisticated adaptive control to find out not only how well the final surface can be shaped, but also how much distortion can be tolerated initially. Additionally, there are also plans to create a metre-sized deposition chamber that would enable studying the surface structure along with packaging unfolding processes for a large-scale primary mirror.

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Why isn’t there an sound in space?

“In space, no one can hear you scream.” You may have heard this saying. It’s the tag line from the famous 1979 science fiction movie “Alien.” It’s a scary thought, but is it true? The simple answer is yes, no one can hear you scream in space because there is no sound or echo in space. I’m a professor of astronomy, which means I study space and how it works. Space is silent – for the most part.

How sound works

To understand why there’s no sound in space, first consider how sound works. Sound is a wave of energy that moves through a solid, a liquid or a gas. Sound is a compression wave. The energy created when your vocal cords vibrate slightly compresses the air in your throat, and the compressed energy travels outward.

A good analogy for sound is a slinky toy. If you stretch out a Slinky and push hard on one end, a compression wave travels down the Slinky. When you talk, your vocal cords vibrate. They jostle air molecules in your throat above your vocal cords, which in turn jostle or bump into their neighbours, causing a sound to come out of your mouth.

Sound moves through air the same way it moves through your throat. Air molecules near your mouth bump into their neighbours, which in turn bump into their neighbours, and the sound moves through the air. The sound wave travels quickly, about 1,223 kilometres per hour, which is faster than a commercial jet

 Sound in the solar system

Scientists have wondered how human voices would sound on our nearest neighbouring planets. Venus and Mars. This experiment is hypothetical because Mars is usually below freezing, and its atmosphere is thin. unbreathable carbon dioxide. Venus is even worse – its air is hot enough to melt lead, with a thick carbon dioxide atmosphere.

On Mars, your voice would sound tinny and hollow, like the sound of a piccolo On Venus, the pitch of your voice would be much deeper, like the sound of a booming bass guitar.The reason is the thickness of the atmosphere. On mars the thin air creates a high-pitched sound,and on venus the thick air creates a low-pitched sound. The team that worked this out simulated other solar system sounds, like waterfall on saturn’s moon titan.

Deep space sounds

While space is a good enough vacuum that normal sound can’t travel through it, it’s actually not a perfect vacuum, and it does have some particles floating through it. Beyond the Earth and its atmosphere, there are five particles in a typical cubic centimetre – the volume of a sugar cube- that are mostly hydrogen atoms.

By contrast, the air you are breathing is 10 billion billion (1019) times more dense. The density goes down with distance from the Sun, and in the space between stars there are 0.1 particles per cubic centimetre. In vast voids between galaxies, it is a million times lower still fantastically empty.

The voids of space are kept very hot by radiation from stars. The very spread-out matter found there is in a physical state called a plasma. A plasma is a gas in which electrons are separated from protons. In a plasma, the physics of sound waves get complicated. Waves travel much faster in this low-density medium, and their wavelength is much longer.

In 2022, NASA released a spectacular example of sound in space. It used X-ray data to make an audible recording that represents the way a massive black hole stirs up plasma in the Perseus galaxy cluster, 250 million light years from Earth. The black hole itself emits no sound, but the diffuse plasma around it carries very long wavelength sound waves.

The natural sound is far too low a frequency for the human ear to hear, 57 octaves below middle C which is the middle note on a piano middle of the range of sound people can hear. But after raising the frequency to the audible range, the result is chilling – it’s the sound of a black hole growling in deep space.

Space is a vacuum

So what about in space? Space is a vacuum, which means it contains almost no matter. The word vacuum comes from the Latin word for empty. Sound is carried by atoms and molecules, In space, with no atoms or molecules to carry a sound wave, there’s no sound. There’s nothing to get in sound’s way out in space, but there’s nothing to carry it, so it doesn’t travel at all. No sound also means no echo. An echo happens when a sound wave hits a hard, flat surface and bounces back in the direction it came from By the way, if you were caught in space outside your spacecraft with no spacesuit, the fact that no one could hear your cry for help is the least of your problems. Any air you still had in your lungs would expand because it was at higher pressure than the vacuum outside. Your lungs would rupture. In a mere 10 to 15 seconds, you’d be unconscious due to a lack of oxygen.

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What is the mysterious object in the James Webb telescope?

A team of international astrophysicists has discovered many mysterious objects that were hidden in images from the James Webb Space Telescope. These include six potential galaxies that should have emerged so early in the history of the universe and are so massive that they should not be possible under current cosmological theory.

These candidate galaxies may have existed roughly 500 to 700 million years after the Big Bang. That places them at more than 13 billion years ago, close to the dawn of the universe. Containing nearly as many stars as the modern-day Milky Way, they are also gigantic. The results of the study have been published in the journal Nature in February

Not the earliest discovered

 Launched in December 2021, the James Webb Space Telescope is the most powerful telescope ever sent into space by us. The candidate galaxies identified this time from its data, however, aren’t the earliest galaxies observed by Jams Webb. Another group of scientists spotted four galaxies observed that likely formed 350 million years after the Big band. Those galaxies, however, were nowhere as massive as the current findings.

While looking at a stamp-sized section of an image that looked deep into a patch of sky close to the Big Dipper (a constellation, also known as the Plough), a researcher spotted fuzzy dots that were way too bright and red. In astronomy, red light usually equals old light. As the universe expands the light emitted by celestial objects stretches, making it redder to human instruments.

Based on their calculations, the team was also able to suggest that the candidate galaxies they had discovered were also huge. Containing tens to hundreds of billions of sun-sized stars worth of mass, these were akin to our Milky Way.

Might rewrite astronomy books

As current theory suggests that there shouldn't have been enough normal matter at that time to form so many stars so quickly, proving it might rewrite astronomy books. And even if these aren't galaxies, then another possibility is that they are a different kind of celestial object, making them interesting.

For now, the discovery has piqued the interest of the researchers and the astronomical community. More data and information about these mysterious objects from James Webb is what is being sought after to confirm that these candidate galaxies are actually as big as they look, and date as far back in time.

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How about learning a bit about the stellar world?

Every star is a giant, bright ball of hot gas. Ever wondered how the stars form and how they die eventually? How about learning a bit about the stellar world?

One septillion stars, that’s almost the number of stars estimated to exist in our universe, Our Milky Way alone contains more than 100 billion stars. The nearest star to us is our Sun. Every star is a giant ball of hot gas. They are the building block of galaxies. “We are made of star stuff,” said noted astronomer Carl Sagan. It means that whatever we are composed of whatever our physical bodies are made of the raw materials that make up our physical bodies were created from the matter from long-extinguished stars. How about learning a bit about the stellar world?

Stars and their birth

Stars are made of huge balls of hot gas it is largely composed of hydrogen and small parts of helium and a few other elements. The star is held together because of its own gravity.

Every star goes through its own unique life cycle. Stars are born within hinge clouds of dust and gas called molecular clouds and are scattered throughout the galaxies. The gas in the molecular clouds clump together, forming high-density pockets, and often collide with each other. With each collision, more matter gets added to it and its mass grows. The gravitational force becomes stronger. The clumps of gas and dust then collapse under their own gravitational attraction. As this happens, the material heats up because of the friction and leads to the formation of a protostar which is also called the baby star. The set of stars newly formed from molecular clouds are called stellar clusters.

Life of a star

The energy of a protostar is derived from the heat released by its initial collapse. As years pass by, the high pressure and temperature inside the core of the star lead to a nuclear fusion reaction, where the nuclei of hydrogen atoms combine together to form helium. The energy that gets released post-nuclear fusion is enough to prevent it from collapsing under gravity.

At any time, there are two opposing forces acting on a star that prevent it from collapsing. There is the gravity of the star which tries to shrink the star, while the energy released following the nuclear fusion in the stars core leads to outward pressure. This outward push will resist gravity’s inward squeeze.

When a star is in the phase of undergoing a nuclear fusion reaction, it is called a main sequence star. This is also the longest phase of the star’s life. It has to be noted that as time passes, that is over millions of years, the size, luminosity and temperature of the star also change. The gas in the star is its fuel and its mass determines how long the star will live. This is because a massive star will end up burning a lot of fuel at a higher rate to generate enough energy to prevent it from collapsing: Meanwhile, lower mass stars will burn longer and shine for longer periods, some trillions of years whilst the massive ones may live for just about a few million years.

How does a star die?

When the star runs out of hydrogen to convert into helium, it marks the beginning of the end of the star’s life. Its core collapses leading to the death of the star. A star’s death is largely dependent on its mass. In the case of a lower-mass star, its atmosphere will keep on expanding until it becomes a giant star and the helium gets converted into carbon in its core. Over time the outer layers of the star will get blown off and the cloud of gas and dust expands. This expanding cloud is called a planetary nebula. All that is left now is the core. This is called a white dwarf star which will cool off over the following billions of years.

But what happens in the case of a high-mass star? The fusion leads to the conversion of carbon into heavier elements which then fuel the core. This process produces enough energy to prevent the core from collapsing. This goes on for a few million years until the star runs out of fuel. This is followed by a supernova explosion. The core either becomes a neutron star or a black hole

The supernova explosion is the biggest explosion that occurs in space. It releases material into the cosmos and this matter will then form part of the future molecular clouds and thereby become part of the stars.

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What has the Cassini spacecraft discovered about Saturn?

Saturn’s moon now satisfies what is usually considered the strictest requirement for life

The search for extraterrestrial life is now more serious than probably ever before. And the search just got more exciting with a team of scientists discovering new evidence that the subsurface ocean of Enceladus – Saturn’s moon- contains a key building block for life phosphorus.

The Cassini spacecraft explored Saturn and its system of rings and moons for more than 13 years. Based on data obtained from this mission, the research team directly found phosphorus in the form of phosphates originating from the ice-covered global ocean on the moon. The results were published in the journal Nature in June.

Our fate and phosphates

In the form of phosphates, phosphorus is necessary for all life on Earth. Be it the creation of DNA and RNA, or the bones and teeth in animals and human beings, life as it is today is impossible without phosphates.

Once the Cassini spacecraft discovered the subsurface liquid water on Saturn’s moon Enceladus, it then analysed samples of ice grains and gases erupting from cracks on Enceladus’ surface. When salt-rich ice grains were analysed by Cassini’s Cosmic Dust Analyzer, it showed the presence of sodium phosphates.

Life beyond Earth

The team’s observational results along with laboratory analogue experiments thus suggest that phosphorus is readily available in Enceladus as phosphates. This makes the discovery a major step forward in the search for life beyond our own Earth.

While worlds like our Earth with surface oceans have to reside in a narrow range of distances from their host stars (to maintain temperatures that support surface water), interior ocean worlds can occur over a large range of distances. This is true within our solar system and beyond. The presence of phosphates in Enceladus thereby increases the number of habitable worlds potentially possible across the galaxy.

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What’s the great Attractor?

In the depths of the cosmic ocean, there is a strange force that keeps pulling our galaxy towards it. And inevitably, whatever is near our Milky Way, including nearby galaxies, are being drawn towards this unknown force.

But for the longest time, we couldn’t understand what was the cause of this force or what lay here as this portion of the universe where the attraction is being felt is hidden from our view all thanks to our own galaxy. The force that is pulling the Milky Way lies in the direction of the constellation Centaurus. And the Milky Way’s disk blocks out our view here.

This region, which we can’t look through (with telescopes) from our galaxy, has been called the Zone of Avoidance. And the Great Attractor sits right here, at this 20% of the universe that’s shielded from us.

The only way to get a glimpse of this area is by using X-rays and infrared light.

It was in the 1970s that the Great Attractor was first discovered. It happened when astronomers made detailed maps of the Cosmic Microwave Background (that is, the light left over from the early universe). It was observed that one side of the Milky Way was warmer than the other.

This indicated that the galaxy was vigorously moving through space. The speed was observed to be about 370 miles per second (600 km/s). While astronomers could measure the high speed at which the galaxy was moving, they couldn’t explain its cause or origin.

The Great Attractor is a region of great mass that exerts an immense gravitational pull on our galaxy and surrounding galaxies. It is estimated to have a diameter of about 300 million light-years. It is estimated to be between 150 and 250 million light years away from Earth.

It sits at the centre of a local Supercluster known as the Laniakea Supercluster.

In short, the Great Attractor is the gravitational centre of the Laniakea Supercluster which consists of our galaxy and 100,000 others.

It is not a celestial body, but rather a point in the universe where everything gets attracted to.

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What about space dust as Earth’s sun shield?

The heat and energy from the sun is what drives life on Earth. That said, humanity is now collectively responsible for so much greenhouse gases that Earth's atmosphere now traps more and more of the sun's energy. This has led to a steady increase in the planet's temperature, and global warming and climate change are causes for concern.

One suggested strategy to reverse this trend is to try and intercept a small fraction of sunlight before it reaches Earth. Scientists, for decades, have considered the possibility of using screens, objects or dust particles to block 1-2% of the sun's radiation and thus mitigate the effects of global warming.

Dust to block sunlight

A study led by the University of Utah explored the idea of using dust to block a bit of sunlight. Different properties of dust particles, quantities of dust and the orbits that would work best for shading Earth were studied. The results were published on February 8, 2023 in the journal PLOS Climate.

Launching dust from Earth to a station at the Lagrange Point between Earth and the sun (L1) would prove to be most effective. The prohibitive costs and efforts involved here, however, might necessitate an alternative, which is to launch lunar dust from the moon.

These two scenarios were arrived at after studying a shield's overall effectiveness, which depends on its ability to sustain an orbit that casts a shadow on Earth. In computer simulations, a space platform was placed at the L1 Lagrange Point (point between Earth and the sun where gravitational forces are balanced) and test particles were shot along the L1 orbit.

While a precise launch was able to create an effective shield for a while, the dust would be blown off by solar winds, radiation, and gravity within the solar system. This would mean that such a system would require an endless supply of dust to blast from L1, making the cost and effort involved astronomical.

Moondust might work

 The second scenario of shooting moondust towards the sun might prove to be more realistic as the inherent properties of lunar dust allow it to work as a sun shield. After studying simulations of lunar dust scattered along different courses, an ideal trajectory that aimed towards L1 was realised.

The authors were clear in stating that their study only looks at the possible impact of such a strategy and do not evaluate the logical feasibility of these methods. If it works, this could be an option in the fight against climate change as it would allow us to buy more time.

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Dark Matter: A mystery of the Universe

Dark matter accounts for 27 percent of all matter and energy in the universe. What we see, the regular matter is just 5 percent of the universe. The dark matter can be failed stars or white dwarfs or black holes.

First, there was the Big Bang. For several million years after that, there was nothing – no stars, planets, moons or galaxies. This continued for 150 million years after the great Big Bang. Time went by. The first stars were created. Matter fused, stars clumped together, galaxies collected together. The formation of our planetary system began. To hold the solar system and clusters of galaxies together, we had gravity, our glue. Swiss astronomer Fritz  Zwicky who used the term ‘dark matter first. He coined the term ‘Dunkle Materie’ to denote the invisible matter.

Dark Matter

But in some clusters, the space between the galaxies contains hot gases which cannot be seen using light telescopes. After measuring this gas, the scientists came to the opinion that there is more material involved in these clusters than meets the eye and that they cannot be detected. The undetected matter could amount to some five times the material in the cluster. This invisible matter that cannot be detected is called the ‘dark matter. Dark matter accounts for 27 percent of all matter and energy in the universe. What we see, the regular matter is just 5 percent I of the universe.

It was the Swiss astronomer Fritz Zwicky who used the term ‘dark matter first. He coined the term ‘Dunkle Materie’, which translates to dark matter, to denote the invisible matter. His subject was the Coma galaxy cluster. It should be noted that the speed of revolution of a particular cluster is dependent on the weight and position of the matter in the cluster. When he measured the speed, he found out that the cluster had more mass than it was supposed to meaning there was more matter involved. This was further confirmed by other scientists whose work on other galaxies suggested that they had more mass. The presence of dark matter was thus established.

What makes up Dark Matter

According to scientists, dark matter can be failed stars or white dwarfs or black holes. But these are just suggestions and the dark matter still continues to be a mystery. Scientists have however found ways to indirectly study dark matter. This is done by using gravitational lensing. Studies are still being carried out and we are just unraveling all the secrets of the universe.

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Voyager 1’s tryst with Jupiter and Saturn

On November 6, 1980, Voyager 1 snapped a picture of Saturn while still 8 million km away from it. Scientists discovered a 15th moon orbiting Saturn from the photo the following day. In a year in which it has completed 45 years of operation,

You must be aware that the twin Voyager probes are now travelling in interstellar space, 45 years since their launch. Before they got there, however, they visited the gas giants in our solar system, gleaning a wealth of information from the flybys. While Voyager 2 flew by all four gas giants – Jupiter, Saturn, Uranus, and Neptune, – Voyager 1 focussed on Jupiter and Saturn.

Even though Voyager 1 is the first spacecraft to travel beyond the solar system and reach interstellar space, it wasn’t the first of the probes to be launched. Launched on September 5, 1977-two weeks after Voyager 2 – Voyager 1, however, was the first to race to Jupiter and Saturn.

Gravitational slingshots

The Voyager missions were planned in such a way that they could maximise a special alignment of the outer planets that happens only once in 176 years. This alignment aided the spacecraft to efficiently use their limited fuel as they moved like a slingshot from one planet to another using gravitational assist.

All the successes that Voyager 1 has achieved might have come to nothing right on the day of the launch. Its rocket came within 3.5 seconds of running out of fuel, meaning Voyager 1 wouldn’t have even got off the ground.

Jupiter flyby

Once it did, however, it raced past its twin, going beyond the asteroid belt before Voyager 2 did. And in April 1978, Voyager 1 beamed back the first pictures of Jupiter back to Earth. By March 1979, it had spotted a thin ring around the giant planet. Apart from sending back detailed photographs of Jupiters Galilean moons (lo, Europa, Ganymede, and Castillo), Voyager 1 also found two new moons – Thebe and Metis.

Voyager 1 collected plenty of data and also made some interesting discoveries about Jupiter’s satellites. Following its closest approach to Jupiter on March 5, 1979, when it came within 2,80,000 km, it headed over to Saturn, a journey that took it just a little over a year.

Just like how its visit to Jupiter had a lot of findings, so it was with Saturn as the ringed planet revealed many of its secrets. As it flew ever closer to Saturn in October-November 1980, Voyager 1 spotted a number of moons, observed its rings and already known moons, and collected data that had scientists digging for decades.

Programmed searches

One of the moons that Voyager 1 spotted was Atlas, the 15th moon orbiting Saturn. In a photograph taken by the spacecraft on November 6 when it was still 8 million km away, the moon was visible near the bottom of the picture.

The first of several programmed searches for new satellites of Saturn thus had success right away as the Voyager imaging team scientists discovered the moon on November 7. An inner moon of Saturn, orbiting around the outer edge of Saturn’s A ring, Atlas takes 14.4 hours to complete its trip around the planet.

Unique perspective

Following its closest approach of Saturn on November 12, Voyager 1 looked back on Saturn four days later on November 16, to observe Saturn and its rings from its unique vantage point. With its primary mission concluded following the Saturn encounter, the focus moved to tracking the spacecraft as it headed to interstellar space.

Having recognised that the Voyagers would eventually make it to interstellar space, NASA had placed Golden Records on board the spacecraft. Designed to carry images, music, and voices from Earth out into the cosmos, the Golden Records have spoken greetings in over 50 languages.

Voyager 1 became the first spacecraft to go beyond the solar system and reach interstellar space on August 25, 2012. At that point, Voyager 1 was over 18 billion km away from the sun. Over a decade later, it has travelled even farther and is now over 23 billion km away from the sun. Voyager 1 has enough fuel to supply power to its instruments until at least 2025, after which it will likely stop collecting scientific data.

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What are the secrets of Enceladus moon?

Discovered on August 28, 1789, Enceladus is a natural satellite of Saturn. This moon, which remained in relative obscurity for nearly 200 years, is now one of the most scientifically interesting destinations in our solar system.

The possibility of worlds other than our own Earth where life could exist has enthralled us for a long time. Often seen in the realm of science fiction, we might be inching ever so closer to it in reality as scientists have identified a handful of worlds that have some of the ingredients needed for life. One of them is Enceladus, an icy moon that is the brightest in the solar system.

Enceladus was discovered on August 28, 1789 by British astronomer William Herschel, more popular for discovering the planet Uranus. Little is known about how William went about it and made his discovery.

A dwarf named after a giant

What we do know, however, is that it was William’s son, John Herschel, who gave the moon its name Enceladus, after the giant Enceladus of Greek mythology. In his 1847 publication Results of Astronomical Observation made at the Cape of Good Hope, John suggested names for the first seven moons of Saturn that had been discovered, including Enceladus. He picked these particular names as Saturn, known in Greek mythology as Cronus, was the leader of the Titans.

For nearly two centuries, very little was known about Enceladus. That changed in the 1980s, when the U.S. spacecrafts Voyager 1 and Voyager 2 flew by the moon, capturing images. The pictures indicated that the icy surface of this small moon is very smooth in some places and bright white all over.

Enceladus, in fact, is the most reflective body in the solar system. Scientists, however, didn’t know why this was the case for a few more decades. Enceladus reflective capability implies that it reflects almost all the sunlight that strikes it, leading to extremely cold surface temperatures, of the order of -200 degree Celsius.

E ring and tiger stripes

Shortly after NASA’s Cassini spacecraft began studying Saturn’s system in 2004, Enceladus started revealing its secrets. By spending over a decade in the vicinity of the small moon, including flybys as close as 50 km, Cassini was able to unearth a wealth of information about Enceladus.

Cassini discovered that icy water particles and gas gush from the moon’s surface at about 400 metres per second. These continuous eruptions create a halo of fine dust around the moon, which supplies material for Saturn’s E ring. While a small fraction of this remains in the ring, the remaining falls like snow back onto the moon’s surface, thereby making it bright white. Scientists informally call the warm fractures on Enceladus’ crust from which the water jets come from as “tiger stripes”.

By measuring the moon’s slight wobble as it orbits Saturn and from gravity measurements based on the Doppler effect, scientists were able to determine that these jets were being supplied by a global ocean inside the moon. As this ocean supplies the jet, which in turn produces Saturn’s E ring, it follows that studying material from the E ring is akin to studying Enceladus’ ocean.

While the E ring is mostly made of ice droplets, there is also the presence of nanograins of silica that can be generated only where liquid water and rock interact at temperatures above 90 degrees Celsius. Along with other evidence that has been gathered, this suggests the existence of hydrothermal vents deep beneath this moon’s shell, similar to those on the Earth’s ocean floor.

Orbital resonance

Enceladus takes 33 hours for its trip around Saturn, which is nearly half of the time taken by the more distant moon Dione. Enceladus is thus trapped in an orbital resonance with Dione, whose gravity stretches Enceladus’ orbit into an elliptical shape. This means that Enceladus is sometimes closer to Saturn and at other times farther leading to tidal heating within the moon.

Running just over 500 km across, Enceladus is small enough to fit within the Indian State of Maharashtra, which runs around 700 km north-south and 800 km east-west. What it lacks in size it more than makes up for in stature, as Enceladus has a global ocean, unique chemistry, and internal heat. All this means that even though we still have plenty of data about the moon to pore over, explorers will eventually plan a return to Enceladus to learn more of its secrets.

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WHY ARE JUPITER’S RINGS NOT LIKE THOSE OF SATURN?

If we talk about ringed planets, more often than not every one of us will be talking about Saturn. This, despite the fact that all four giants in our solar system Jupiter, Saturn, Uranus, and Neptune – in fact have rings.

This is likely because Saturn has spectacular rings. While the rings of Jupiter and Neptune are flimsy and difficult to view with stargazing instruments traditionally used, the rings of Uranus aren’t as large as that of Saturn’s.

As Jupiter is bigger than Saturn, it ought to have rings that are larger and more spectacular than that of its neighbour. As this isn’t the case, scientists from UC Riverside decided to investigate it further. Their results were accepted by the Planetary Science journal and are available online.

Dynamic simulation

A dynamic computer simulation was run to try and understand the reason why Jupiter’s rings look the way they do. The simulation accounted for Jupiter’s orbit, the orbits of Jupiter’s four main moons, and information regarding the time it takes for rings to form.

The rings of Saturn are largely made of ice, some of which may have come from comets also largely made of ice. When moons are massive, their gravity can either clear the ice out of the planet’s orbit, or change the ice’s orbit such that it collides with the moons.

Massive moons

The Galilean moons of Jupiter Ganymede, Callisto, lo, and Europa- are all large moons. Ganymede, in fact, is the largest moon in our solar system. The four main massive moons of Jupiter would thus destroy any large rings that might form around the planet. This also means that Jupiter is unlikely to have had large. spectacular rings at any time in the past as well.

Ring systems, apart from being beautiful, help us understand the history of a planet. They offer evidence of collisions with moons or comets, indicating the type of event that might have led to their formation. The researchers next plan to use the simulations to study the rings of Uranus to find out what the lifetime of those rings might be.

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What makes Russia a prominent country in space explorations?

Russia has achieved great heights in the field of space technology and space exploration, and its national space agency is known as Roscosmos. These achievements can be traced back to Konstantin Tsiolkovsky, who is known as the father of theoretical astronautics. His works inspired Soviet rocket engineers, such as Sergey Korolyov, Valentin Glushko, and many others to contribute immensely to the Soviet space programme in its early stages, leading to its participation in what is called the ‘Space Race’.

There is a name that one cannot forget in the history of space expeditions – Sputnik-1. In 1957, this satellite was launched by Russian scientists as the first Earth-orbiting artificial satellite. Later, in 1961, Yuri Gagarin made the first human trip into space. This was followed by a number of other Soviet and Russian space explorations, which include the journey of Valentina Tereshkova in 1963 to become the first woman in space. She flew alone in Vostok 6. Russia also holds the record for the first human to have conducted a spacewalk-in 1965, Alexei Leonov exited the space capsule of the mission Voskhod-2 and walked in space.

Can you guess what other records Russia has in this area? They sent the first animal into outer space. Travelling in Sputnik-2 in 1957, a dog named Laika became the first animal to orbit the Earth. In 1966, Luna-9, landed on the Moon, making it the first spacecraft to achieve a survivable landing on a celestial body. In 1968, Zond-5 completed the mission of circumnavigating the Moon with two tortoises and other life forms from Earth. Later, Russia’s Venera-7 became the first spacecraft to land on Venus. Following this achievement, Mars-3 became the first spacecraft to land on Mars in the very next year 1971. During this time, Russia also sent Lunokhod-1, which became the first space exploration rover. Salyut-1 became the world’s first space station, which was yet again a Russian project. As per the 2021 data, Russia had 167 active satellites in space, which is the world’s third-highest count.

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WHAT WAS THE MERCURY SEVEN MISSION?

On May 15, 1963, the last mission of Project Mercury got under way. Astronaut Gordon Cooper closed out things in style as his flight stretched the capabilities of the Mercury spacecraft to its limits.

The Mercury Seven, also referred to as the Original Seven, were a group of seven astronauts selected to fly spacecraft for Project Mercury – the first human space flight program by the U.S. Even though there were some hiccups, the project, initiated in 1958, was largely successful in its three goals of operating a human spacecraft. investigating an astronaut’s ability to work in space, and recovering spacecraft and crew safely.

Youngest of the Mercury Seven

The final flight of Project Mercury took place in May 1963. The youngest of the Original Seven, astronaut Gordon Cooper, went on to become the first American to fly in space for more than a day during this mission.

Leroy Gordon Cooper Jr. was born in 1927 and served in the Marine Corps in 1945 and 1946. He was commissioned in the U.S. Army after attending the University of Hawaii.

He was called to active duty in 1949 and completed pilot training in the U.S. Air Force. He was a fighter pilot in Germany from 1950 to 1954 and earned a bachelor’s degree at the Air Force Institute of Technology in 1956. He served as a test pilot at Edwards Air Force Base in California until he was selected as an astronaut for Project Mercury. Cooper flew Mercury-Atlas 9, the last Mercury mission, which was launched on May 15, 1963. He called his capsule Faith 7, the number indicating his status as one of the Original Seven astronauts.

Conducts 11 experiments

Longer than all of the previous Mercury missions combined. Cooper had enough time in his hands to conduct 11 experiments. These included monitoring radiation levels, tracking a strobe beacon that flashed intermittently, and taking photographs of the Earth.

When Cooper sent back black-and-white television images back to the control centre during his 17th orbit, it was the first TV transmission from an American crewed spacecraft. And even though there were plans for Cooper to sleep as much as eight hours, he only managed to sleep sporadically during portions of the flight. After 19 orbits without a hitch, a faulty sensor wrongly indicated that the spacecraft was beginning re-entry. A short circuit then damaged the automatic stabilisation and control system two orbits later. Despite these malfunctions and the rising carbon dioxide levels in his cabin and spacesuit. Cooper executed a perfect manual re-entry.

Lands without incident Cooper had clocked 34 hours and 20 minutes in space, orbiting the Earth 22 times and covering most of the globe in the process. This meant that he could practically land anywhere in the globe, a potential pain point that the U.S. State

Department was nervous about. In fact, on May 1, 1963, the country’s Deputy Under Secretary fuel, venting gas that made the spacecraft roll, and more in what felt like a never-ending series during their eight-day mission. They, however, completed 122 orbits, travelling over 5.3 million km in 190 hours and 56 minutes, before safely making their way back to Earth.

After accumulating more than 225 hours in space, Cooper served as the backup command pilot of Gemini 12, which was launched in November 1966, and the backup command pilot for Apollo 10 in May 1969. By the time Cooper left NASA and retired from the Air Force in July 1970, human beings had set foot on the moon, further vindicating the Mercury and Gemini projects that Cooper had been involved with.

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WHAT IS THE SURFACE AROUND A BLACK HOLE THAT REPRESENTS THE DISTNACE OF APPROACH BEYOND WHICH EVEN LIGHT CANNOT ESCAPE?

A black hole is an astronomical object with a gravitational pull so strong that nothing, not even light, can escape it. A black hole’s “surface,” called its event horizon, defines the boundary where the velocity needed to escape exceeds the speed of light, which is the speed limit of the cosmos.

In astrophysics, an event horizon is a boundary beyond which events cannot affect an observer. Wolfgang Rindler coined the term in the 1950s. In 1784, John Michell proposed that gravity can be strong enough in the vicinity of massive compact objects that even light cannot escape. At that time, the Newtonian theory of gravitation and the so-called corpuscular theory of light were dominant. In these theories, if the escape velocity of the gravitational influence of a massive object exceeds the speed of light, then light originating inside or from it can escape temporarily but will return. In 1958, David Finkelstein used general relativity to introduce a stricter definition of a local black hole event horizon as a boundary beyond which events of any kind cannot affect an outside observer, leading to information and firewall paradoxes, encouraging the re-examination of the concept of local event horizons and the notion of black holes. Several theories were subsequently developed, some with and some without event horizons. One of the leading developers of theories to describe black holes, Stephen Hawking, suggested that an apparent horizon should be used instead of an event horizon, saying, “gravitational collapse produces apparent horizons but no event horizons.” He eventually concluded that “the absence of event horizons means that there are no black holes – in the sense of regimes from which light can’t escape to infinity.”

Any object approaching the horizon from the observer’s side appears to slow down, never quite crossing the horizon. Due to gravitational redshift, its image reddens over time as the object moves away from the observer.

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WHAT IS THE STUDY OF CAVES CALLED?

 

Speleology, scientific discipline that is concerned with all aspects of caves and cave systems. Exploration and description of caves and their features are the principal focus of speleology, but much work on the chemical solution of limestone, rates of formation of stalagmites and stalactites, the influence of groundwater and hydrologic conditions generally, and on modes of cave development has been accomplished within this discipline. Speleology requires, essentially, the application of geological and hydrological knowledge to problems associated with underground cavern systems. Amateur exploration of caves, as a hobby, is called spelunking.

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WHAT IS THE EXPLORATION OF CAVES CALLED?

Caving – also known as spelunking in the United States and Canada and potholing in the United Kingdom and Ireland – is the recreational pastime of exploring wild cave systems (as distinguished from show caves). In contrast, speleology is the scientific study of caves and the cave environment.

The challenges involved in caving vary according to the cave being visited; in addition to the total absence of light beyond the entrance, negotiating pitches, squeezes, and water hazards can be difficult. Cave diving is a distinct, and more hazardous, sub-speciality undertaken by a small minority of technically proficient cavers. In an area of overlap between recreational pursuit and scientific study, the most devoted and serious-minded cavers become accomplished at the surveying and mapping of caves and the formal publication of their efforts. These are usually published freely and publicly, especially in the UK and other European countries, although in the US, these are generally private.

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WHAT IS THE DIFFERENCE BETWEEN CONSTELLATIONS AND ASTERISMS?

Constellations are the 88 recognized patterns and groups of stars. These groups and patterns are usually associated with mythology. Today, constellations are not only the groups of stars, but now refers to the entire region of the sky that it takes up.

Asterisms are groups of stars that do not form their own constellations, but instead, are inside of constellations. The Big Dipper is an example of this. The Big Dipper is an asterism inside of the constellation Ursa Major. So I believe that asterisms are smaller than the constellations that they’re in, but not necessarily bigger than all constellations.

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WHAT IS AN ASTERISM?

An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept then the formally defined 88 constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux.

Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky.

The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observations. For example the Summer Triangle is a purely observational physically unrelated group of stars, but the stars of Orion’s Belt are all members of the Orion OB1 association and five of the seven stars of the Big Dipper are members of the Ursa Major Moving Group. Physical associations, such as the Hyades or Pleiades, can be asterisms in their own right and part of other asterism at the same time.

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WHICH IS THE SMALLEST CONSTELLATION?

The smallest constellation is Crux, the Southern Cross. A small group of four bright stars that forms a Latin cross in the southern sky, Crux is visible from latitudes south of 25 degrees north and completely invisible in latitudes above 35 degrees north (in the United States, roughly north of Texas).

Originally it was part of the constellation Centaur, but became its own constellation during the 16th century when it was used as a valuable navigation tool by explorers. Its area is calculated at about 68 square degrees.

Blue-white ? Crucis (Acrux) is the most southerly member of the constellation and, at magnitude 0.8, the brightest. The three other stars of the cross appear clockwise and in order of lessening magnitude: ? Crucis (Mimosa), ? Crucis (Gacrux), and ? Crucis (Imai). ? Crucis (Ginan) also lies within the cross asterism. Many of these brighter stars are members of the Scorpius–Centaurus association, a large but loose group of hot blue-white stars that appear to share common origins and motion across the southern Milky Way.

Crux contains four Cepheid variables, each visible to the naked eye under optimum conditions. Crux also contains the bright and colourful open cluster known as the Jewel Box (NGC 4755) on its eastern border. Nearby to the southeast is a large dark nebula spanning 7° by 5° known as the Coalsack Nebula, portions of which are mapped in the neighbouring constellations of Centaurus and Musca.

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WHICH IS THE LARGEST CONSTELLATION?

Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees, and also the longest at over 100 degrees. Its southern end borders Libra and Centaurus and its northern end borders Cancer. It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy. Commonly represented as a water snake, it straddles the celestial equator.

Despite its size, Hydra contains only one moderately bright star, Alphard, designated Alpha Hydrae. It is an orange giant of magnitude 2.0, 177 light-years from Earth. Its traditional name means “the solitary one”. Beta Hydrae is a blue-white star of magnitude 4.3, 365 light-years from Earth. Gamma Hydrae is a yellow giant of magnitude 3.0, 132 light-years from Earth.

Hydra has one bright binary star, Epsilon Hydrae, which is difficult to split in amateur telescopes; it has a period of 1000 years and is 135 light-years from Earth. The primary is a yellow star of magnitude 3.4 and the secondary is a blue star of magnitude 6.7. However, there are several dimmer double stars and binary stars in Hydra. 27 Hydrae is a triple star with two components visible in binoculars and three visible in small amateur telescopes. The primary is a white star of magnitude 4.8, 244 light-years from Earth. The secondary, a binary star, appears in binoculars at magnitude 7.0 but is composed of a magnitude 7 and a magnitude 11 star; it is 202 light-years from Earth. 54 Hydrae is a binary star 99 light-years from Earth, easily divisible in small amateur telescopes. The primary is a yellow star of magnitude 5.3 and the secondary is a purple star of magnitude 7.4. N Hydrae (N Hya) is a pair of stars of magnitudes 5.8 and 5.9. Struve 1270 (?1270) consists of a pair of stars, magnitudes 6.4 and 7.4.

The other main named star in Hydra is Sigma Hydrae (? Hydrae), which also has the name of Minchir, from the Arabic for snake’s nose. At magnitude 4.54, it is rather dim. The head of the snake corresponds to the ?shlesh? Nakshatra, the lunar zodiacal constellation in Indian astronomy. The name of Nakshatra (Ashlesha) became the proper name of Epsilon Hydrae since 1 June 2018 by IAU.

Hydra is also home to several variable stars. R Hydrae is a Mira variable star 2000 light-years from Earth; it is one of the brightest Mira variables at its maximum of magnitude 3.5. It has a minimum magnitude of 10 and a period of 390 days. V Hydrae is an unusually vivid red variable star 20,000 light-years from Earth. It varies in magnitude from a minimum of 9.0 to a maximum of 6.6. Along with its notable color, V Hydrae is also home to at least two exoplanets. U Hydrae is a semi-regular variable star with a deep red color, 528 light-years from Earth. It has a minimum magnitude of 6.6 and a maximum magnitude of 4.2; its period is 115 days.

Hydra includes GJ 357, an M-type main sequence star located only 31 light-years from the Solar System. This star has three confirmed exoplanets in its orbit, one of which, GJ 357 d, is considered to be a “Super-Earth” within the circumstellar habitable zone.

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HOW MANY CONSTELLATIONS ARE RECOGNIZED BY INTERNATIONAL ASTRONOMICAL UNION?

There are 88 modern constellations recognized by the International Astronomical Union (IAU). The list of the modern constellations was adopted by the IAU in 1922. The constellation boundaries as we know them today were set in the late 1920s. 36 modern constellations lie principally in the northern celestial hemisphere, while 52 are found in the southern sky.

The list of the modern constellations and the abbreviations used for them were produced by American astronomer Henry Norris Russell and approved by the IAU in May 1922. Russell’s list corresponded to the constellations listed in the Revised Harvard Photometry star catalogue, published by Harvard College Observatory in 1908. The constellation boundaries were drawn by Belgian astronomer Eugène Delporte and officially adopted in 1928.

The 88 modern constellations have different origins. Most of them are roughly based on the 48 ancient constellations catalogued by the Greek astronomer Claudius Ptolemy of Alexandria in his Almagest, an ancient astronomical treatise written in the 2nd century CE. These constellations are mostly associated with figures from Greek mythology. They include Andromeda, Cassiopeia, Perseus, Pegasus, Hercules, Orion, Ursa Major, Ursa Minor, Canis Major, Canis Minor, Eridanus, and the 12 zodiac constellations.

However, Ptolemy did not create these constellations. They were already well-known to observers long before his time. Even though they are called Greek constellations, they were not necessarily created by the Greeks. Depictions of some of the ancient constellations or the asterisms they are known for go back to prehistoric times and their creators are unknown.

Fifty of the modern 88 constellations are based on the Greek ones. Only one of Ptolemy’s constellations – Argo Navis – is no longer in use. Once the largest constellation in the sky, Argo Navis represented the ship of Jason and the Argonauts. It was divided into three smaller constellations – Carina, Puppis and Vela – by the French astronomer Nicolas-Louis de Lacaille in the 18th century. The three smaller constellations remain in use.

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WHY DOES A COMET HAVE A TAIL?

A comet has two tails. One is a dust tail pushed by light from the sun. Wired Science blogger Rhett Allain uses physics to explain how light can push on matter.

There are two tails because there are two ways the comet can interact with the sun. Everyone thinks about light coming from the sun. However, there is also the solar wind. The solar wind is really just charged particles (like electrons and protons) that escape from the sun due to their high velocities. These charged particles then interact with the ionized gas produced from the comet.

The other tail is due to an interaction with the dust produced by the comet and the light from the sun. Really, it is this interaction that I want to talk about.

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WHAT IS THE FROZEN PART OF COMETS IS CALLED ?

The nucleus is the solid core of a comet consisting of frozen molecules including water, carbon monoxide, carbon dioxide, methane and ammonia as well as other inorganic and organic molecules — dust. According to ESA the nucleus of a comet is usually around 10 kilometers across or less.

Comets are separated into three distinct parts called the tail, nucleus and the coma which ensures its workability. Comets work in the sense that they tend to be more explicit when they come closer to the source of illumination, the Sun. The tail of a comet is made up of three other parts, the ion tail, the hydrogen envelope, and the dust tail. All these are also vital for the movement of the comet both to and from the sun as indicated below.

The nucleus of a comet is made up of ice, gas, dust, and rocks. It is found right at the center of the head of a comet. The nucleus of a comet is often frozen. The part which is occupied by the gas in the comet’s nucleus is made up of carbon dioxide, the carbon monoxide, ammonia, and methane.

The comet’s area which is made up of the nucleus encompasses between 0.6 to around 6 miles. At times, it is even more than this distance. The nucleus, following this combination of materials, carries the most mass of the comet. The nucleus of a comet is also regarded as one of the darkest objects ever witnessed in the space.

Credit : Earth eclipse

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WHAT IS IT CALLED WHEN A COMET IS CLOSEST TO THE SUN?

Coma. As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud around the comet known as the coma. According to science website howstuffworks.com the coma is often 1,000 times larger than the nucleus. Outside the coma is a layer of hydrogen gas called a hydrogen halo which extends up to 1010 meters in diameter. The solar wind then blows these gases and dust particles away from the direction of the Sun causing two tails to form. These tails always point away from the Sun as the comet travels around it. One tail is called the ion tail and is made up of gases which have been broken apart into charged molecules and ions by the radiation from the Sun. Since the most common ion, CO+ scatters the blue light better than red light, to observers, this ion tail often appears blue.

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HOW MANY COMETS HAVE BEEN IDENTIFIED SO FAR?

The current number of known comets is: 3,743. Comets are frozen leftovers from the formation of the solar system composed of dust, rock, and ices. They range from a few miles to tens of miles wide, but as they orbit closer to the Sun, they heat up and spew gases and dust into a glowing head that can be larger than a planet. This material forms a tail that stretches millions of miles.

Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet’s orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the Sun for millions of miles. There are likely billions of comets orbiting our Sun in the Kuiper Belt and even more distant Oort Cloud.

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DOES THE TEMPERATURE OF NEPTUNE CHANGE?

Neptune, the farthest planet in the solar system, takes more than 165 years to complete an orbit around the sun. As Neptune has an axial tilt, it experiences seasons, just like our Earth.

Sensing emitted heat : Neptune’s great distance from the sun and the longer period of revolution, however, implies that its seasons change slowly, lasting over 40 Earth years each. A new research published in April in Planetary Science Journal revealed that the temperatures in Neptune’s atmosphere have fluctuated unexpectedly over the last two decades, even though this period only represents half of a Neptune season.

An international team of researchers that included scientists from Leicester and NASA’s Jet Propulsion Laboratory used observations that effectively sensed heat emitted from Neptune’s atmosphere. They combined two decades worth of thermal infrared images of Neptune from the European Southern Observatory’s Very Large Telescope; Gemini South telescope in Chile; Subaru Telescope, Keck Telescope, and the Gemini North Telescope in Hawaii; and spectra from NASA’s Spitzer Space Telescope.

Cooler than we thought :  Analysing this data allowed the researchers to reveal a complete picture of trends in Neptune’s temperatures like never before, and some of these revelations were unexpected, to say the least. Since the beginning of reliable thermal  imaging of Neptune in 2003, the datasets indicate a decline in Neptune’s thermal brightness, which came as a surprise to the researchers. This means that the globally averaged temperature in Neptune’s atmosphere has come down by almost 8 degrees Celsius from 2003 to 2018, making the planet cooler than what we thought  before.

The data from Neptune’s south pole, however, reveals a different dramatic change. Observations of this region show that Neptune’s polar stratosphere has warmed up by nearly 11 degrees Celsius from 2018 to 2020, reversing the previous cooling trend.

As of now, the causes for these stratospheric temperature changes are unknown and follow-up observations of the temperature will be needed to further assess these findings. Some of those causes might be revealed by the James Webb Space Telescope that is set to observe both Uranus and Neptune later this year.

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What is the longest drive record Perseverance Mas rover has set?

NASA’s Perseverance Mars rover set a new record for the longest drive in a single Martian day, travelling 245.76 metres (806 feet) on the surface of Mars on February 4. The previous record was held by NASA’s Opportunity rover in 2005 (214 metres/702 feet). Perseverance broke a second record, surpassing its own longest AutoNav drive. NASA integrated this function into a rover for the first time. When in AutoNav, the rover drives autonomously by navigating through 3D maps and software that help it avoid obstacles. This feature makes Perseverance faster as compared to when it’s being remotely controlled by NASA personnel; it would only traverse about 200 metres a day which would lengthen the timeline of exploration. Perseverance landed on the red planet a year ago and is on a mission to seek out signs of ancient microbial life. It has collected six samples of Martian rock and atmosphere, over 50GB of science data and has sent back over 100,000 images. It has also snapped two selfies on the Martian surface!

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Where are most meteorites found?

Researchers from Delft University of Technology in The Netherlands have used artificial intelligence to create a treasure map of zones in which to find meteorites hidden in Antarctic ice.

Sixty-two per cent of all meteorites recovered on Earth were found in Antarctica, making this cold continent a hotbed for space research. These meteorites provide a unique view into the origin and evolution of the solar system.

Meteorites have been accumulating in Antarctica for millennia, falling from space and becoming embedded in ice sheets within the continent’s interior. As the glaciers slowly flow, the meteorites are carried with them. If a glacier comes up against a large obstacle, in areas like the Transantarctic Mountains, the ice rises and meteorites are brought to the surface. Dry Antarctic winds gradually erode the ice, exposing the meteorites. As more ice rises to the surface, the process repeats. Given enough time, a significant accumulation of meteorites builds up.

Researchers say that satellite observations of temperature, ice flow rate, surface cover and geometry are good predictors of the location of meteorite rich areas, and expect the “treasure map’ to be 80 per cent accurate. Based on the study, scientists calculate that as many as 300,000 meteorites are out there on the Antarctic landscape.

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Why do the footprints of astronauts remain unchanged on the surface of the moon?

We are pretty proud of the human flight to the Moon and our footprints on the lunar surface. But did you know these footprints can last a million years on the surface of the Moon? It has been decades since humans last set foot on the Moon, but its surface is still marked with the historic footprints of the 12 astronauts who walked across it Unlike on Earth, there is no erosion by wind or water on the Moon because it has no atmosphere. The Moon is geologically inactive there are no earthquakes or volcanoes. So, nothing gets washed away and nothing gets eroded.

However, the Moon is exposed to bombardment by meteorites, which change the surface. One little spacerock could easily wipe out a footprint on the moon. And since the Moon has no atmosphere, it is exposed to the solar wind, a stream of charged particles coming from the sun, and over time this acts almost like weather on Earth to scour surfaces on the moon, but the process is very, very slow.

On July 20, 1969, Neil Armstrong put his left foot on the rocky Moon. It was the first human footprint on the Moon. They had taken TV cameras with them. The two astronauts walked on the Moon. They picked up rocks and dirt to bring back to Earth. The astronauts had much work to do. Then, the Eagle went back to meet astronaut Collins. He was in the Command Module working.

When Neil Armstrong and Buzz Aldrin visited the moon 50 years ago, they left roughly 100 objects behind, including a portion of their lunar lander, the American flag and, yes, various kinds of trash. Those objects are still there, surrounded by rugged bootprints marking humanity’s first steps on another world. But that site, called Tranquillity Base, may not be as enduring as the legacy those prints represent.

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What is future of the sun?

Nothing in the Universe is permanent. One of the most profound rules in all the Universe is that nothing lasts forever. With gravitational, electromagnetic and nuclear forces all acting on matter, practically everything we observe to exist today will face changes in the future. Even the stars, the most enormous collections that transform nuclear fuel in the cosmos, will someday all burn out, including our Sun. In about five billion years, the Sun will exhaust the hydrogen fuel in its core and start burning helium, forcing its transition into a red giant star. A red giant is a dying star in the final stages of stellar evolution. When the Sun turns into a red giant, it will expand and engulf the inner planets- possibly even Earth. After spending about one billion years as a red giant, the star will become a white dwarf, packing most of its initial mass into a sphere roughly the size of Earth. It will eventually become a black dwarf.

In about 5 billion years time the Sun will have exhausted all the hydrogen at its core. The core, which by then will consist of helium nuclei, will then shrink and nuclear reactions will take place in a large shell outside the core, rather than the core itself. The outer regions of the Sun will greatly expand and it will become a red giant.

It is unclear exactly how large the Sun will get when it becomes a red giant. Current estimates are that it will expand to 100-250 times its current diameter (ref 2). If we take the lower value, the innermost planet Mercury (but not Venus and the Earth) will be swallowed up by the Sun.  At the higher value, the Earth would also be inside the Sun.

When all of the helium in the core has been converted into carbon, nuclear reactions in the core will once again stop. The Sun will start to convert helium into carbon in a shell outside its core but will become more and more unstable. It will vary widely in brightness as it flares up and ejects some of its outer layers into space and then contracts again. Eventually the whole of the outer regions of the Sun will be blown away forming a glowing shell of plasma called a planetary nebula.

With the lower value, where the Sun expands to 100 times its current radius  value, on Earth the Sun would appear 10,000 times larger than it is today. The surface temperature of the Earth would be around 1500 degrees Celsius, hot enough for it glow a dull red colour. The Earth would have lost its atmosphere long before this and will be a bone dry scorched airless desert on which it will be impossible for life to exist.

Credit : Explaining Science

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Did the fruit flies survive in space?

Fruit flies were the first organisms sent to space. For many years before sending mammals into space, such as dogs or humans, scientists studied Drosophila melanogaster (the common fruit fly) and its reactions to both radiation and space flight to understand the possible effects of space and a zero-gravity environment on humans. Starting in the 1910s, researchers conducted experiments on fruit flies because humans and fruit flies share many genes. On February 20, 1947, fruit flies became the first living and sentient organisms to go to space and return, which paved the way for human exploration. At the height of the Cold War and the Space Race, flies were sent on missions to space with great frequency, allowing scientists to study the nature of living and breeding in space. Scientists and researchers from the Soviet Union and the United States both used fruit flies for their research and missions.

Fruit flies have been used in recent years as the reality of Mars and Moon colonization becomes clearer. These flies further the understanding of the effects of weightlessness on the cardiovascular system, the immune system, and the genes of astronauts. Fruit flies have been invaluable assets to scientific discoveries that humankind have made, especially discoveries about space travel.

Mankind has long admired the heavens and wondered about space. Even after the Space Race was completed, advancements in space travel continued. Researchers continue to study the ability of life to survive in the harsh atmosphere of space, promote commercial development, expand and advance knowledge, and prepare future generations for exploration. Throughout time, Animals in space have ensured suitable conditions for human exploration. Larger animals including dogs, monkeys, cats, mice, and others, have been vital to many excursions, as have insects.

The fruit fly has frequently been utilized for space travel, due to its comparable genetics to that of humans. The short gestation period and quick maturing process allows their continued use. Additionally, a female fruit fly can lay one hundred eggs daily, and each egg requires less than ten days to fully mature. Since three-quarters of its genome compares to other organisms, fruit flies frequently proceed humans in space travel because their entire genetic makeup, including the sex chromosomes, have been sequenced by scientists.

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