Occasionally in the news headlines like: " Scientists discover a star that exploded 1500 years ago." And how do you know if they were not there? And, astronomers seem determined to go to space becoming more and more powerful telescopes that allow them to look further and further. Why the effort? Why do you want to look so far?
(Hubble Space Telescope)
not have been bored of the nearest stars, or that they are aware of memory, no. They do it because looking at how far you can see the past. That's right! And this is nothing new, do not leave to think that it has discovered a time machine or something. Notice that I did not say go back in but to see the past. As they say, space is a window into the past.
Let us explain a little bit. Surely you have heard, but a trick home to see how far struck by lightning, is counting the seconds after you see it, until you hear the thunder and divide by 3. Sound travels faster (on a 340 m / s), but the champion of the gears is very light (300,000 km / s!!). For this reason, if lightning strikes at 1km, we see him almost instantly, while the thunder (sound) take 3 seconds to reach us. The sound, despite being fast, over long distances is not enough and takes time to reach our ears.
Same thing happens in space with light. The light, which was the speed superchampion in the vastness of space, it falls short. The distances are so so great that even light suffers such a delay until it reaches our eyes. If you remember the previous entry Why can not exceed the speed of light? , we had a light year is not a measure of time, but long (specifically the distance light travels in one year). When we say that a star is 4 light years, meaning that the light from it has taken 4 years to reach us. Therefore, looking at that star, we're seeing, what reaches our eyes, not what is happening there now, but what happened in that star for 4 years. We are seeing the past!
Extrapolating this, if we observe a star that is a million light years we are seeing what the universe was a million years ago! Hence the interest of astronomers look far. Looking mainly to investigate the origin of the universe and how it was in its infancy, this technique is very necessary.
And the record? Well I think for now we have the Hubble and is in seeing what happened makes 13.2 billion years!
The truth of the fluorescent
molecular Trojan horses ...
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