Thursday, October 24, 2013

Looking back in time

We all want to go back in time. Well, nobody knows if that is possible. But looking at the past is quite easy.
Every time you look at something that is far away, you are actually looking at the past. Because even though light travels very fast, it takes some time to leave that thing and reach your eyes.
Horizon is about 5 km away. So when you look at a ship on the horizon you are seeing the past, though only fraction of a second ago.
But when you are looking at stars, it’s another matter. They are far away, and light takes a long time to reach us. When you look at the sun, you are looking 8 minutes in the past. Alpha Centauri, the star nearest to us is the third brightest star in the sky. When you look at Alpha Centauri, you are seeing things that happened four years ago.
Now scientists have found a galaxy (which is nothing but a large group of stars) that is really far far away. It is farther than anything we have known before. When you look at this galaxy, you will be taken 1300 crore years in the past. At that time, our universe was very young, a crying baby merely 80 crore years old!
Alas, even through the most powerful telescope in the world, this newly found galaxy appears as a faint dot of light. That is definitely not an arresting sight for non-astronomers like you and me.
Scientists say that they can find galaxies even farther away, taking us very close to the beginning of the universe. To look so far back, they are building telescopes nine times bigger than the biggest we have today.

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