Category Science

Which is the second largest moon of Saturn?

One of the many things that makes our Earth really special is the presence of an oxygen atmosphere. This oxygen richly contributes to various processes happening here on Earth, making the planet a cradle of life.

Even though we have taken an interest in celestial bodies and explored space, near and far, Earth remained the only one with an oxygen atmosphere for long. That changed in 2010 when a spacecraft for the first time directly captured molecules of an oxygen atmosphere at a world was one of the Saturn’s many moons, Rhea.

The stars of Louis

The discovery of Rhea took place on December 23, 1672 by Italian astronomer, mathematician and engineer Giovanni Cassini. Rhea was the second of four Saturn satellites that Cassini discovered and the third to be found orbiting the ringed planet. Cassini named the four moons that he discovered – lapetus, Tethys and Dione in addition to Rhea – Sidera Lodoicea (“the stars of Louis”), in honour of King Louis XIV of France.

This name, however, never picked up outside of France. The names that we recognize them today with were given over a century later by English astronomer John Herschel, Son of astronomer William Herschel, the discoverer of Uranus, John suggested the name Rhea in 1847.

Saturn’s second largest

Saturn’s second largest satellite after Titan, Rhea has a mean radius of 764 km – equivalent in size to a little over a 10th of our Earth. Like Tethys and Dione, Rhea is also tidally locked in phase with its parent, meaning that one side of the moon always faces Saturn.

For centuries after its discovery, Rhea remained merely a tiny dot to astronomers. It was the Voyager (1 and 2) encounters in 1980 and 1981 that finally threw some light on it. Images from these encounters suggested that Rhea’s features could be divided into two regions. While the heavily centered terrain had craters larger than 40 km across, parts of the equatorial and polar region have craters less than 40 km across.

Following the Voyager encounters there were no missions to the region until the Cassini spacecraft made its way to orbit around Saturn in 2004. Cassini then made a number of targeted close flybys of Rhea in the decade that followed.

Tenuous atmosphere

In 2010, Cassini was able to detect around Rhea a very thin atmosphere, known as an exosphere, that was infused with oxygen and carbon dioxide. Even though the source of carbon dioxide isn’t certain, the oxygen is believed to arise when Saturn’s magnetic field rotates over Rhea. The moon’s water-ice surface is peppered with energetic particles that were trapped in Saturn’s magnetic field, and the chemical reactions that ensure decompose the surface and release oxygen.

When compared to what we have at Earth, oxygen at Rhea’s surface is estimated to be about 5 trillion times less dense. Despite the current minuscule composition, the formation of oxygen and carbon dioxide could well lead to complex chemistry.

The average age of Rhea’s plains is theorized to be around four billion. We’ve known this moon, which has been around for so long, for a few centuries now. During this time, we have learned a little bit about it, making it more than just a dot for us. There is, however, plenty still left to find out.

 

Picture Credit : Google

How technology is used to keep in touch with loved ones?

Technology has received its share of criticism over the years, especially when it comes to social interaction. With the advent of computers and smartphones, many of us have been accused of spending less time with friends and family, and more with gadgets. However, the same technology can be used to keep in touch with loved ones. Here’s how:

Send them a mail

While writing a letter is always an option, you can send your loved ones an email as well. It gets delivered in an instant and is versatile, allowing you to incorporate images and documents. Share your vacation pictures or tell them how the year has been for you and wait for a reply.

Email is a quick and hassle-free way of connecting with your loved ones.

Connect on video

Video calling is one of the best technologies available to us. It helps bring those staying far away closer to us, and is more personal than chat or email.

Use one of the many video calling software on your phone or laptop to call and connect with your loved ones. You’ll feel like they are right next to you.

Send E-greetings

Gone are the days when we shared greeting cards with friends and family on special occasions. However, technology has added its own twist to those cards, enabling you to customize them and send them electronically. There are several e-greeting sites online. You can choose the ones you like and send them to your loved ones.

Alternatively, you can use your design skills to create your own greeting card and mail it.

Send them a gift

With the boom in e-commerce, you can easily send a gift to your dear ones. Not sure about what they like? Browse their social media accounts or ask common friends.

Alternatively, you can send them an e-giftcard which will enable them to buy whatever they want from an e-commerce site.

Share memories

With the availability of cloud storage, you can collaborate with your loved ones and create a repository of photographs of everyone in your circle. It will stay forever, and you can always browse through them for a walk down memory lane.

 

Picture Credit : Google

How climate changes in Antarctica exploit invasive species?

According to a study, at the current rate of warming, the area of ice-free land in the Antarctic peninsula, in the west, is set to rise by 300% in the next century. That means invasive species will have more land and more water (thanks to melting ice) species of fly will face-off against invaders. The exact effect is difficult to predict precisely, say scientists.

Antarctica is home to species that can gather in greater densities than those in temperate or tropical climates, said Convey, pointing to microscopic arthropods known as Collembola, a million of which can squeeze into a square meter.

The thousands of researchers and 50,000 tourists who visit the remote continent every year risk upsetting this balance by bringing plant and insect life with them.

One type of grass, Poa annua, has already managed to carve out a beachhead on some islands, and humans have brought with them two species of fly.

Some species do manage to arrive by natural means from the tip of South America 1,000 km (600 miles) away, but they do not manage to establish themselves permanently.

The thousands of researchers and 50,000 tourists who visit the remote continent every year risk upsetting this balance by bringing plant and insect life with them.

One type of grass, Poa annua, has already managed to carve out a beachhead on some islands, and humans have brought with them two species of fly.

Some species do manage to arrive by natural means from the tip of South America 1,000 km (600 miles) away, but they do not manage to establish themselves permanently.

 

Picture Credit : Google

What are some invasive species in Antarctica?

  • Specimens of non-native species of flies, spiders, caterpillars, butterflies, wasps, beetles, moths, slugs, bugs, ants, moss and grass have been found in Antarctica over the years. Ground beetles, in particular, have been extremely invasive, preying on native insects.
  • In a study, scientists found that foreign plants such as annual bluegrass, chickweed and yellow bog sedge, were establishing themselves in Antarctica. They found that seeds and other detachable plant structures were stuck to cold-weather gear that travellers and researchers brought to the continent. Disturbingly, 49% to 61% of foreign plants that reach Antarctica are cold-adapted and can withstand and colonise in extreme conditions.
  • Scientists with the British Antarctic Survey have discovered that a species of fly originally from South Georgia – the chironomid midge, has flourished since its accidental introduction to Signy Island in the Antarctic in the 1960s. It has expanded to more than 650 feet away from its original site, and in some areas is more numerous than any of the native insects. The fly likely travelled unnoticed on the plants brought to Antarctica for research. In the 1990s and early 2000s, its population started to explode.
  • Some species do manage to arrive by other natural means. But it is humans who bring in 99% of invasive species, say scientists.
  • Transport of invasive species can be minimized by careful cleaning and checking of clothing, footwear, construction materials, food, equipment and vehicles sent to Antarctica.

 

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Why invasive species are considered threats?

Invasive species cause harm to the ecosystem in many ways:

  • In the absence of natural predators, a new and aggressive species can breed, spread quickly and overrun the local habitat. Native species may not have evolved defences against the invader, further boosting the invaders’ growth.
  • The threats from an invasive species also include preying on native species and outcompeting them for resources, thereby restricting the growth of native species.
  • Some invasive species are capable of changing the conditions in an ecosystem, such as the soil chemistry.
  • Invasive species can change the food web in an ecosystem by destroying native food sources.
  • People who depend on the ecosystem’s native resources will also be affected.

 

Picture Credit : Google

How do invasive species spread?

  • Some species arrive in a new area through migration.
  • Some are spread unintentionally by human activities. When people travel, they often inadvertently carry alien species along. For instance, insects may arrive in a new place by travelling on luggages.
  • Some species are introduced on purpose as pets or to combat pests, which turn out to be invasive in the new place.
  • Ships can carry aquatic organisms in their ballast water, while smaller boats may carry them on their propellers. Insects can get into wood, shipping palettes, and crates that are shipped around the world.
  • Some ornamental plants can escape into the wild and become invasive.
  • Illegal smuggling/trading of fruits and vegetables across borders can introduce not only potentially harmful new plant species but also any insects and parasites that may live in them.
  • Higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species—such as garlic mustard, kudzu, and purple loose strife—to move into new areas. 

 

Picture Credit : Google