How is it possible for the Hubble telescope to capture pictures of the universe in it’s infant stages?
Read an article on line about this and I am not sure I understand how it works; the article actually referred to the telescopes ability to photograph "back in time" and it lost me completely. I mean, does the Telescope view what’s out there now and calculate backwards to come to a conclusion as to what the universe was like then? Anyone who can shed light, please do.
This is an effect caused by the speed of light and the vast distances in space.
For example, it takes about 8 minutes for light from the sun to reach the earth. So when we look at the sun, we’re actually seeing what it looked like when the light left it, 8 minutes ago. If the sun suddenly vanished or exploded, it would be 8 minutes before we could see it!
If we extend this to stars and galaxies that are very, very far away, the same holds true! The nearest star to us is about 4 Light years away. That means, it takes 4 years for the light to travel to us. So when we look at that star today, that is what it actually looked like 4 years after the light left that star!
Continuing in distance, we can see stars that are thousands and thousands of light years away. Our galaxy, the Milky Way, is roughly 100,000 light years all the way across. So some stars we can see, we are actually seeing what they looked like almost 100,000 years ago.
And then there are other galaxies we can see, and these can be millions and millions of light years away. The furthest galaxies we’ve seen are about 13 BILLION light years away. So when we look at those galaxies, that is what they looked like 13 billion years ago!
We really are looking back in time! We won’t know what that galaxy looks like at THIS instant for another 13 billion years, once the light that leaves them right now reaches us at that point!
So, the farther away you look into space, the farther back in time you can look! Of course, there’s a limit to how far we can see: you can’t see farther than the age of the universe! This is because there hasn’t been enough time for light to travel that far. So if we get the distance of the farthest object that we can see, then we can roughly find out a minimum age of the universe! Scientists have estimated it at being a little over 13 billion years old, so that’s about as far back as we can look.
Hope this helped explain it for you!
This is an effect caused by the speed of light and the vast distances in space.
For example, it takes about 8 minutes for light from the sun to reach the earth. So when we look at the sun, we’re actually seeing what it looked like when the light left it, 8 minutes ago. If the sun suddenly vanished or exploded, it would be 8 minutes before we could see it!
If we extend this to stars and galaxies that are very, very far away, the same holds true! The nearest star to us is about 4 Light years away. That means, it takes 4 years for the light to travel to us. So when we look at that star today, that is what it actually looked like 4 years after the light left that star!
Continuing in distance, we can see stars that are thousands and thousands of light years away. Our galaxy, the Milky Way, is roughly 100,000 light years all the way across. So some stars we can see, we are actually seeing what they looked like almost 100,000 years ago.
And then there are other galaxies we can see, and these can be millions and millions of light years away. The furthest galaxies we’ve seen are about 13 BILLION light years away. So when we look at those galaxies, that is what they looked like 13 billion years ago!
We really are looking back in time! We won’t know what that galaxy looks like at THIS instant for another 13 billion years, once the light that leaves them right now reaches us at that point!
So, the farther away you look into space, the farther back in time you can look! Of course, there’s a limit to how far we can see: you can’t see farther than the age of the universe! This is because there hasn’t been enough time for light to travel that far. So if we get the distance of the farthest object that we can see, then we can roughly find out a minimum age of the universe! Scientists have estimated it at being a little over 13 billion years old, so that’s about as far back as we can look.
Hope this helped explain it for you!
References :
Shed light??
Light is the answer!
When you look through a telescope (any telescope) you are seeing the viewed object or objects way back in time as the light takes time to reach the earth.
In other words, you are seeing the star or galaxy as it was millions or billions of years ago, NOT as it is now.
The most distant object viewed so far is about 8.1 gigaparsecs, i.e. 8.1 x 10^9 parsecs, from the earth, which means light has travelled this distance to get here. The light from this object takes some 15 to 20 billion years to get here. But this is an extreme case. Most of the stuff observed is a lot nearer than this. But you see the point, I hope.
[8.1. gigaparsecs is 25 x 10^22 kilometers]
References :
Everyone, including grade school children, knows Einstein’s equation. He explained how the speed of light is constant (in a vacuum). Ignoring small deviations, like bending around a star or galaxy, light moves in a straight line. Because it won’t go any faster, it takes a definite amount of time to reach your eye. The light from our Sun takes about 8 minutes to reach Earth. The light from the edge of the Milky Way takes much longer – between 13000 – 83000 years depending on where you turn your telescope. That light you see is an old image of the Milky Way. It is even possible that the light you see from a particular star has already died and will take considerably longer for you to confirm it. Consequently, light from the farthest reaches of space is portraying an image that is incipient.
References :
When you see the Sun you see it as it was about 8 minutes ago. If you look at the central area of our own galaxy you are seeing it as it was about 30,000 years ago. If you are looking at something which is over 10 billion light years away then you are seeing it as it was over 10 billion yeas ago, which would be the early universe. Everything you see is in the past.
References :