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The Dawn of the Universe and Time as Explained by Saint Vallalar and Natural Scientists –A comparative study - II
THE UNIVERSE
Stars appear to twinkle because we see them through the layers of the earth’s atmosphere. Light is distorted as it passes through these layers, so that the amount we see changes constantly. Stars nearest the horizon seem to twinkle the most because the light is passing through a greater depth of atmosphere. Stars do not twinkle when viewed from space, so telescopes in space, such as the Hubble, give the best possible view of distant stars and galaxies.
Star facts:
A star is a luminous body of gas, mostly hydrogen and helium. Stars generate light which makes it possible for us to see them with a telescope or the naked eye.
Brightest
Not counting the sun, brightest star as seen from the Earth is Sirius, known as the Dog Star, in the constellation of Canis Major. It has a diameter of 149,598,020 km and is more than 24 times brighter than the sun. The star LBV 1806-20 in the constellation of Sagittarius may be 40 millions times as bright as our Sun, but dust clouds make it almost invisible from the Earth.
Largest
The largest star is VY Canis Majoris, which has an estimated diameter of about 1950 times greater than sun. For comparison if it were a foot ball, the sun would be no bigger than a pinhead.
Nearest
Proxima Centauri, discovered in 1915, is 4.22 light years (39,953,525,879,212 km) from Earth. A spaceship moving at 40000 Km/Hr – which is faster than any human has yet travelled in space, would take more than 114,000 years to reach it.
Supernovae
These are vast explosions in which a whole star blows up. They are extremely bright, rivalling for a few days the combined light output of all the stars in the galaxy. Supernovae are rare- the last in our galaxy was seen in 1604 by the German Astronomer Johannes Kepler.
Quasars
These are extremely distant radio galaxies-galaxies giving out large amounts of radio energy- and the brightest objects in the universe. Their radio emission is typically 1000,000 to 100,000,000 times greater than that of a normal galaxy.
Black holes
A black hole is a star that has collapsed into itself . It has a surface gravity so powerful that nothing can escape from within it.
Traveling at the speed of Light
In space, light travels at a speed of 299,792.46 km a second, or 1,079,252,956 km an hour. When we look at even the nearest star we see light that left it more than four years ago.
Light years
Distances in space are often described as light years; here are the times it takes light to reach the various bodies in space.
· Moon: 1.26 seconds
· Sun: 8 minutes 17 seconds
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· Proxima Centauri - Nearest star: 4.22 years
· Most distant star in our galaxy : 62,700 years
· From nearest body outside our galaxy: 174,000 years
· Furthest visible star : 2,309,000 years
· Most distant known quasar: 14,000,000,000 years.
To be continued..,
Arutperum Jodhi Arutperum Jodhi
Thaniperum karunai Arutperum Jodhi
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