Category Science

From the biggest whale in the ocean to a tiny mouse, all life on Earth has one thing in common – it is all made from the same stuff.

Stardust

Nearly everything that makes up our bodies, and everything else on Earth, was created when dying stars exploded. These explosions send raw materials like carbon and oxygen hurtling across space, and these raw materials are what we are made of. That means that you are made of stardust! When the universe started, there was just hydrogen and a little helium and very little of anything else. Helium is not in our bodies. Hydrogen is, but that’s not the bulk of our weight. Stars are like nuclear reactors. They take a fuel and convert it to something else. Hydrogen is formed into helium, and helium is built into carbon, nitrogen and oxygen, iron and sulfur—everything we’re made of. When stars get to the end of their lives, they swell up and fall together again, throwing off their outer layers. If a star is heavy enough, it will explode in a supernova.

So most of the material that we’re made of comes out of dying stars, or stars that died in explosions. And those stellar explosions continue. We have stuff in us as old as the universe, and then some stuff that landed here maybe only a hundred years ago. And all of that mixes in our bodies.

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Although there may be life elsewhere in our Solar System, we haven’t discovered it yet. The only place we know has life for sure is Earth. Our home planet is at just the right distance from our Sun for liquid water to exist, and has all the other key ingredients to make life possible.

Life is a characteristic that distinguishes physical entities that have biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have ceased (they have died), or because they never had such functions and are classified as inanimate. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, or potential synthetic life as “living”. Biology is the science concerned with the study of life.

There is currently no consensus regarding the definition of life. One popular definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve. However, several other definitions have been proposed, and there are some borderline cases of life, such as viruses or viroids.

Recipe for life

In the mixing bowl are the key ingredients needed for life as we know it:

You will need:

Raw materials, such as oxygen, nitrogen, and carbon
Liquid water
Energy

Raw material

The raw materials needed for life are found all over Earth – for example in soil. However soil needs water and energy from the Sun before life can appear. Life as we know it contains specific combinations of elements including carbon, hydrogen, nitrogen, and oxygen that combine to form proteins and nucleic acids which can replicate genetic code. All the basic elements are formed in stars and distributed throughout space as a result of giant explosions called supernovas. Since these essential chemicals are quite common in other places in the Universe we can expect that the development of life somewhere else is also possible.

Water

Liquid water is essential for life. It allows crucial changes to take place between raw materials. Liquid water is essential because biochemical reactions take place in water. Water is also an excellent solvent that easily dissolves and carries nutrients and other compounds in and out of cells. Life forms are usually made primarily of water. In fact, our human bodies are more than 60% water.

Energy

Life on Earth would not be possible without a constant source of energy, such as the Sun. Organisms require energy to assimilate or put together the chemicals that form an individual. Energy is also required for the organism to grow, reproduce, and respond to the environment. Energy sources may include other organisms, light, or inorganic compounds. The most common source of energy on the Earth is photosynthesis, which transforms sunlight into food. This process will not work very well for the outer Solar System, because not much light reaches such great distances. However, we can look to extremophiles here on Earth for help in figuring out where and what to search for. Extremophiles live in extreme conditions and typically get their energy from a source other than the sun.

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Earth and Venus are about the same size, and are made up of similar rocky materials. They are also neighboring planets. However, Venus and Earth are also very different. Venus has an atmosphere that is about 100 times thicker than Earth’s and has surface temperatures that are extremely hot. Venus does not have life or a water ocean like Earth does. Venus also rotates backwards compared to Earth and the other planets.

But that’s where the similarities end! Venus is a deadly world. It‘s boiling hot, covered in volcanoes, and cloaked in an atmosphere of deadly poisonous gases

Volcanoes: Venus is covered in volcanoes. There is evidence that some may still be erupting. On Earth, volcanoes are mainly of two types: shield volcanoes and composite or stratovolcanoes. The shield volcanoes, for example those in Hawaii, eject magma from the depths of the Earth in zones called hot spots. The lava from these volcanoes is relatively fluid and permits the escape of gases. Composite volcanoes, such as Mount Saint Helens and Mount Pinatubo, are associated with tectonic plates. In this type of volcano, the oceanic crust of one plate is sliding underneath the other in a subduction zone, together with an inflow of seawater, producing gummier lava that restricts the exit of the gases, and for that reason, composite volcanoes tend to erupt more violently.

Barren surface: There are no rivers or lakes on the surface of Venus. The only rain it gets is acid rain that would burn trough your skin.

Toxic clouds: Venus is covered in clouds of sulphuric acid. The atmosphere is so thick it would crush you in seconds.
Atmosphere: Earth’s atmosphere protects it from dangerous space radiation, and contains gases like oxygen that we need to breathe. Venus’s atmospheric pressure is greater than that of any other planet – more than 90 times that of Earth’s. This pressure is equivalent to being almost one kilometre below the surface of Earth’s oceans. The atmosphere is also very dense and mostly carbon dioxide, with tiny amounts of water vapour and nitrogen. It has lots of sulphur dioxide on the surface. This creates a Greenhouse Effect and makes Venus the hottest planet in the solar system. Its surface temperature is 461 degrees Celsius across the entire planet, while Mercury (the closest planet to the Sun) heats up to 426 Celsius only on the side facing the Sun.
Life: Earth is home to an amazing variety of plants and animals.
Water: About 71 per cent of Earth’s surface is covered by water. It is a vital ingredient for life.

Temperature: The surface temperature on the planet Earth goes only to about 100 degrees Fahrenheit, which makes it possible for life to thrive on this planet. On the other hand, the surface temperature on the planet Venus is nine times hotter than that on planet Earth. As such, it is extremely impossible for any form of life to survive and thrive on Venus’ surface.

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Mercury has a rocky surface, but inside is a very large metallic core, part of which is molten (liquid).

Crust: Mercury has a thick crust that is composed mostly of silicate rocks. Mercury may have small ice caps at its north and south poles; this ice stays frozen inside deep craters that are shaded from sunlight. 

Mantle: Beneath the crust it is a mantle (also made of silicate rocks) that is hundreds of kilometers thick. 

Core: At the center of Mercury is a partly-molten iron core about 2,300 miles (7,500 km) in diameter (almost half of the diameter of Mercury). This core accounts for about 80% of Mercury’s mass. This core generates a magnetic field (which is how we know that Mercury has an iron core). 

Density: Mercury has a density of 5,430 kg/m3, slightly less than that of Earth. Mercury is the second-densest planet in the solar system (after Earth) because of its large iron core. 

People have been observing Mercury for a very long time, but nobody knows who discovered it. Sometimes it can be seen from Earth around sunset and sunrise. Sunrise and sunset on Mercury are spectacles to behold. Two and one half times larger in the sky than seen on Earth, the sun appears to rise and set twice during a Mercurian day. It rises, then arcs across the sky, stops, moves back toward the rising horizon, stops again, and finally restarts its journey toward the setting horizon. These aerial maneuvers occur because Mercury rotates three times for every two orbits around the sun and because Mercury’s orbit is very elliptical.

Visible at night: Mercury is not the only planet that can be seen with the naked eye. Mercury can generally be observed with a naked eye as it has the sun as a bright backdrop. Mercury is best observed with the naked eye during times right before and after the sun has set, which gives enough light pollution to contrast the shadow of Mercury. A general time to try and view Mercury with your naked eye is 90 minutes before sunrise or after sunset.

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 Mercury is the closest planet to the Sun and the least explored of the four inner rocky planets. Its surface is covered in greyish-brown dust and looks similar to our Moon, with lots of craters where it has been hit by space rocks. Scientists think there is no possibility of life here.

Mercury is smallest of the eight planets in our Solar System – it is only slightly bigger than the Earth’s Moon.

Mercury is a world of extreme temperatures. By day it is scorching hot, but at night it is very cold.

Mercury is not the hottest planet in the solar system. With no atmosphere to trap heat, surface temperatures on Mercury can swing from 800 degrees Fahrenheit during the day to -290 degrees Fahrenheit at night. Mercury may even have reservoirs of ice sitting deep inside permanently shadowed craters at its poles. By contrast, the surface of hazy Venus sits at a sweltering 880 degrees Fahrenheit year-round, making it the hottest planet in our solar system.

Lack of an atmosphere also means Mercury’s surface is pockmarked by numerous impact craters, since incoming meteors don’t encounter any friction that would cause them to burn up. Seen via telescopes and spacecraft, Mercury looks like a battered world covered in overlapping basins, soaring cliffs, and occasional smooth plains.

Bright lines called crater rays also crisscross the surface where impacts crushed the rock and kicked up reflective debris. One of the most notable features on Mercury is Caloris Basin, an impact crater about 960 miles wide that formed early in the planet’s history. Mercury has no rings, no moons, and a relatively weak magnetic field.

Picture Credit : Google

 As well as heat and light, the sun blasts out special particles called solar wind. When these get trapped by Earth’s magnetic field near the poles they can create spectacular light shows, called auroras. Even though auroras are best seen at night, they are actually caused by the sun. The sun sends us more than heat and light; it sends lots of other energy and small particles our way. The protective magnetic field around Earth shields us from most of the energy and particles, and we don’t even notice them.

But the sun doesn’t send the same amount of energy all the time. There is a constant streaming solar wind and there are also solar storms. During one kind of solar storm called a coronal mass ejection, the sun burps out a huge bubble of electrified gas that can travel through space at high speeds.

When a solar storm comes toward us, some of the energy and small particles can travel down the magnetic field lines at the north and south poles into Earth’s atmosphere.

There, the particles interact with gases in our atmosphere resulting in beautiful displays of light in the sky. Oxygen gives off green and red light. Nitrogen glows blue and purple.

Picture Credit : Google