Long Time Ago in a Galaxy Far Far Away

Because of their great distances—hundreds of millions of parsecs away—the farthest "normal" galaxies are very faint. (We'll talk about what normal means in just a moment.) At such extreme distances, it becomes difficult to even see such galaxies, much less study their shapes or how they are distributed in space. But as far as we can see, there is little difference between normal distant galaxies and normal galaxies closer to home.

The operative word here is normal. Out in the farthest reaches of space, we see some objects that are not normal—at least they are not what we're accustomed to seeing in our cosmic neighborhood.

What does this tell us? Remember that the universe has a speed limit, the speed of light, and that information can travel no faster than this speed. Thus the farther away a certain star or galaxy might be, the longer it has taken its light to reach us.

So not only are we seeing far into space, we are in a very real sense seeing back into time. The strange objects that lurk in the distant universe existed in its earliest times. To study a quasar is to see into the origin of galaxies.

Telescopes Mastery

Telescopes Mastery

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