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Friday, March 7, 2008

Twinkle Twinkle Little Star……Some Starry Facts!

Have you ever wondered why some stars twinkle? Stars seem to twinkle because we see them through the layers of the Earth’s atmosphere. The atmosphere around the Earth distorts the light as it passes through it. This is the reason why the stars nearest the horizon appear to twinkle the most. The stars that are viewed from space do not twinkle. That is the reason why telescopes in space, such as the Hubble, give the best possible view of distant stars. Here are some more starry facts.

What is a star?
A star is a luminous body of gas, mostly hydrogen and helium. Stars can be seen with the naked eye or a telescope because they generate light.

Which is the brightest Star?
The brightest star (not counting the sun) as seen from the Earth is Sirius, also known as the Dog Star. This star is present in the constellation of Canis Major and has a diameter of 149,598,020 Km, which is more than 24 times brighter than the sun.
Another star, called Cygnus OB2 No 12 was discovered in the year 1992 in the galaxy very far from the Earth. This star may be the brightest star in the galaxy, as it is believed to be six million times as bright as our sun.

Which is the heaviest star?
A star in the large Magellanic Cloud called HDE 2698 10 has been discovered by the Hopkins Ultraviolet Telescope to be 190 times as heavy as our Sun.

Which is the largest star?
The M-class supergiant Betelgeuse, or Alpha Orionis is the largest star, which can be seen in the constellation of Orion. This star has a diameter of 700 million km, which is 500 times greater than that of the Sun.

Which is the nearest star?
The nearest star is the Proxima Centauri, which is about 4.22 light years away from the Earth. This star was discovered in 1915.

What is a Supernova and Black Hole?
A supernova occurs when a whole star is blown up. The explosion that occurs is very bright. However, Supernovae are a rare occurrence and the last one to have been seen in our galaxy was in 1604 by a German astronomer, Johannes Kepler.

In contrast, a Black hole is a star that has collapsed into itself. It has a surface gravity so powerful that nothing can escape from it.

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