Article by Paramita Ghosh
Astronomy is not possible without Gastronomy!! Believe it or not, astronomy is quite a delicious stream to study. If you are a ‘eating while reading’ kinda person, then it can pretty well arrange some evening snacks for your comfort. So, if you are a gourmet, relish them one by one.
Hola! I hope you’ll like to begin with a hot and steamy cup of tea or the very famous Teapot asterism which you can find in the Sagittarius, a zodiacal constellation that can be found in summer skies. It is mostly identified with various Greek mythologies. Often depicted as a Centaur, an archer, a half-human half-horse carries a bow and an arrow that is aimed towards J-shaped Scorpious, the scorpion constellation in the sky. The centre of our galaxy lies in this direction of the Sagittarius constellation. This area of sky is overflowed with different exotic nebulae, star clusters. Many of the stars of this constellation are too faint to see from light polluted areas. There are eight bright stars that form this very famous teapot asterism.
But what does an asterism mean? A small group of stars that forms a visible pattern yet not an official constellation, take an example- Big dipper (Saptarshi Mandal in Bengali) of Ursa major.
Now, among these eight bright stars that make the teapot pattern, the stars Kaus Media, Al Nasal and Kaus Australis make the spout. Kaus Media and Kaus Borealis and Phi Saggitarii form the lid; Kaus Media, Phi sagittarii, Ascella and Kaus Australis take the shape of the body of the teapot. And Phi Sagittarii, Ascella and Tau Sagittarii and Nunki make the handle. If you are quite fortunate enough with pitch dark sky region and with a good imaginative power, you can pretty well get to see that our milky way apparently looks like a steam coming out of the tea pot!!
As the story goes like, the Scorpion wanted to show off his brand new teapot by arranging a tea party. So he invited Orion, the hunter and his two hunting dogs Canis major and Canis minor. But the scorpion missed it that they were actually winter sky constellations. So, by the time the invitees arrived, the whole sky rotated so far that all the tea poured out of the teapot, leaving only the steam behind.
Are you done with tea? Now it’s our donut time! I mean, it is the donut shaped Van Allen Belt time!
A magnetic field surrounding the earth and protecting us from the continuous solar wind coming from Sun and deadly cosmic rays and charged particles, the magnetosphere (a space around a planet that is controlled by its magnetic field. Earth’s magnetosphere is a direct result of the slamming of charged particles of solar wind). But this force field is itself a swirling field of radiation. Yes, I’m talking about Earth’s two donut shaped Van Allen radiation belt are trapped by the earth’s magnetosphere. This giant swath is named after its discoverer James Van Allen, an American physicist, after launching of the American spacecraft Explorer 1in 1958. Here, two layers of belts have merged and there is no real gap between them. This radiation belts are made up of high energy protons, electrons and heavier atomic ions starting about 600 kms above the earth’s surface. This belt is intense over the equator and effectively absent at the poles. These particles are so energized (about 10-100 meV range) that it can easily penetrate spacecraft shells and human flesh. Therefore both people and spacecraft are quite vulnerable to this radiation belt. That is why space shuttle and ISS fly much closer to the earth at an altitude about 400 km, well below Van Allen belt. Few spacecrafts (Pioneer 3, Explorer 4) were designed to explore the extent of this belt and they found that Van Allen belt ends about 6000 km above the earth. But they uncovered a second, even larger belt that is 10,000 km above the earth and extends about 65,000km.
The inner belt is quite stable but when it expanded, its orbit affected the ISS and other satellites orbit! The outer one changes overtime when solar storms pass through the earth, huge number of charged particles is trapped by the belt. Some scientists think that there may be a connection between solar storms hitting the earth and the size of the belt though it is unpredictable. As the Van Allen belt may change its shape, this belt is a threat to the space operations! Therefore, for deeper study of this deadly stuff, NASA sent Van Allen probe mission (in picture) in 2012 at an altitude from 500 km from it.
The trick was that two identical spacecraft will constantly move around Earth and studying the composition i.e., the behavior of the charged particles, why its shape fluctuates when a geomagnetic storm passes and to what extent it’s going to be a threat to the spacecrafts. “The researchers found that the inner belt– the smaller belt in the classic picture of the belts– is much larger than the outer belt when observing electrons with low energies, while the outer belt is larger when observing electrons at higher energies”- NASA wrote.
Another fascinating finding was, when the heavily energized ions slammed this belt, the energies get dissipated and the shape of the belt got distorted. But it eventually regained its former shape after the solar storms died down and again the energization process began. In March 2017, scientists reported two unexpected results — i) the inner most belt radiate less than previously estimated, this means less protective shield is gonna required for the satellites and space shuttles. ii) low frequency radio signal sent from earth created an artificial shield around the planet by pushing back the belt.
Good news is that researchers have also found that these two belts have become further away from the earth than they were in 1960s! Would you mind taking a voyage through these two yummy donuts to travel to the moon or the mars?
Till then, Eat. Be with Hashtag Kolkata. And Repeat!!
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