i aint no genius but i am struggling to grasp the fact that the hubble space telescope can take photo’s from like back in time… i just read an article on yahoo… and it makes little sense to me.
Well you’re looking back in time every time you look at the moon! Light from the moon takes 2.56 seconds to reach us so every time you look at it, that’s how it looked like 2.56 seconds ago (not currently). The moon isn’t even that far away either when you compare it to other things in the universe.
So you can imagine how far back in time we are looking when we look through Hubble. Because Hubble can see so much into the distance, the images we are getting have taken many years to reach us, so we are actually seeing what happened many years ago.
Light travels at 300,000 kilometres per second (186,000 miles per second). You can imagine how far light travels in one year then. Lots! That should give you an idea of how big the universe is when it could take 4.22 ‘light years’ just to see the nearest star out of our solar system.
Yep. The universe is pretty big lol!
January 24th, 2010 at 11:17 pm
no. Well, yes. but not really
Light takes a long time to travel the distances it does in space. So essentially, the pictures the telescope is taking are of events that happened a long time ago. It doesn’t look back in time as such tho.
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January 24th, 2010 at 11:34 pm
Well you’re looking back in time every time you look at the moon! Light from the moon takes 2.56 seconds to reach us so every time you look at it, that’s how it looked like 2.56 seconds ago (not currently). The moon isn’t even that far away either when you compare it to other things in the universe.
So you can imagine how far back in time we are looking when we look through Hubble. Because Hubble can see so much into the distance, the images we are getting have taken many years to reach us, so we are actually seeing what happened many years ago.
Light travels at 300,000 kilometres per second (186,000 miles per second). You can imagine how far light travels in one year then. Lots! That should give you an idea of how big the universe is when it could take 4.22 ‘light years’ just to see the nearest star out of our solar system.
Yep. The universe is pretty big lol!
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January 25th, 2010 at 12:07 am
Light travels at a certain speed, so the light we are seeing happened along time ago, so they do a calculation and determine when, in time, the light the Hubble sees, happened. About as simple as I can get.
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January 25th, 2010 at 12:38 am
It’s a somewhat inexact expression used to capture the interest of readers.
Whatever the telescope sees is what reaches it at that moment. However, light from a faraway object will have been traveling for many years, so the image recorded at the telescope is of the faraway object as it was all those years ago, but only seen in the here and now. Hence the expression "look back in time"
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January 25th, 2010 at 12:57 am
Light travels very fast, but it does travel at a finite speed. You see some object as it was when the light left it. For instance, it takes light 8 minutes to travel from the sun to the Earth- so we see the sun as it was 8 minutes ago. If the sun turned off, it would be eight minutes before we knew about it.
To see the early universe, all you need to do is look a VERY long way away- it takes light billions of years to travel from some parts of the universe, so you see these parts of the universe as they were at a very young age.
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January 25th, 2010 at 1:23 am
It is not actually traveling back in time.
The light (constellations that it can see) has to travel just like you would travel to the shopping mall.
Only difference is light travels much faster than a car.
Sunlight takes about 8 minutes and 19 seconds to reach Earth. Speed of light is
miles per second ≈ 186,000
miles per hour ≈ 671 million
The speed of light (usually denoted c) is a physical constant 186,000 miles per second
So the star you see, that light has been traveling for a long time depending on how far the star is from earth.
Because it takes 8 minutes and 19 seconds for light to travel from the sun to the earth we are seeing the suns light from 8 minutes and 19 seconds ago.
Now if a star is millions of times farther from us than the sun it will takes much more time for that light to reach the earth. That light that eventually reaches earth is as old as it took to travel from the star to the earth.
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January 25th, 2010 at 1:56 am
The same way your eyes look back in time. When you look at this answer, it takes time for the light from your computer screen to get to the retinas at the back of your eyeballs. That’s so short a time you’d never notice, but when you look at the moon, what you see is the moon as it was a few seconds ago, not now. When you look at the sun, you see it as it was a few minutes ago, not now. And when you see things 600,000,000 light years away, you see things as they were 600,000,000 years ago.
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January 25th, 2010 at 2:25 am
the hubble space telescope "looks back in time" by taking pictures of galaxies that are billions of light years away. it can take pictures of stars that are 4.2 light years away, to as much as 13.1 billion light years away, approximately 600 billion years before the "Big bang".
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