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This is the Triangulum Galaxy, a member of our local group residing about 3 million light years away.  Below is the Io, one of Jupeter’s moon and as of January 2009, Jupiter has 49 official, named moons and 14 more unofficial ones still under consideration.

How do you photograph something that’s 3 million light years away? Why doesn’t it take the light from over there 3 million years to travel to whatever supercamera we have?  Well, I got thisquestion from fuckyeahspace and below is his answer to the question.

Every photon that landed on the developing tray of the telescope that took this picture had been traveling for 3 million years before it ended it’s journey. What we see here is what the galaxy looked like 3 million years ago, and 3 million years in the future we will be able to see what it looks like right now. Our Sun formed about 4.5 billion years ago, so if there are any planets 4.5 billion light years away from us, they are right now seeing the explosion that created our solar system. Even the light from our own sun is 8 minutes old before it reaches us.

Light is the fastest-traveling thing in the universe, and nothing can travel faster than it. This is something we sometimes forget. When we see things like the Andromeda Galaxy and remark at it’s short distance from us at 2.5 million light years, we must remember that homo sapiens have only been around for about 250,000 years (if you accept the theory of evolution, and if not then we’ve been around for a significantly shorter amount of time). We will never be able to do more than look at our beautiful galactic neighbors and imagine that on some planet circling some star someone is doing the same to us.

Actually when I read this, I had questions myself that made me research into this a little more for a layman’s point of view.   Lets face it, the explanation above is quite confusing to most of us and you would not get it in just one reading and you would not understand it either without any other knowledge of related knowledge.  Here is what I gathered that supported the answer and finally answered my questions.

We are able to see these great astronomical bodies because of the use of telescopes.  The word “Telescope” comes form the two Greek words, “tele” meaning “far” and “skopein” meaning “far-seeing”.  Meaning it can see far away objects as If they were near.

There are two telescopes invented the refracting telescope which was invented by Galileo and the reflecting telescope which was invented by Isaac Newton.   Below are images on how both telescope differentiates.

Light enters through the front objective lens and then passes through the eyepiece lens before reaching your eye.

In a reflecting telescope, light bounces off mirrors instead of passing through lenses. This Newton’s invention paved the way for all the great telescopes to come and probably the best example of this kind of telescope  would be the  Hubble Space Telescope which orbits 600 kilometers above the Earth.  Because it is above the Earth’s atmosphere, Hubble is able to see faraway objects more clearly than any telescope in history.

So here is the next question, if telescope receives light, how can we see these object that does not emit light and even still see it even at that distance?  The answer in this would be because light is reflected off those objects same as how we see each other.  So the next question will be, why do we not see it at an instant why does it take years before we see the glory of the universe?  Well, light has to travel even if its just one foot away. Its just that at one foot it is too near that we think that we see it an instant but the real truth is it has to travel before we can really see it.  Below is a table of how fast light travels in a given distance for you to clearly see the picture I am talking about.

Well for additional information telescopes aren’t limited to just the light we can see.  Invisible kinds of light, like radio waves and x-rays, are used by astronomers, too. When scientists first used x-rays to look at the sky, they discovered black holes. When they used radio waves, they found the event called the Big Bang.  Now scientists are working on a new kind of telescope that uses gravitational waves.

Thanks to Yes Mag and Wikipedia for the answers.