In astronomy we look into the past. How are distance calculations adjusted for the time of light years?

Question

An object is one million light years away which means that it has moved for one million years since the image reached us. How is the distance in light years adjusted for the movement occurring in the light transition interval?

Answer 1

I'll answer this one while being brutally honest...
I don't even KNOW if astronomers do that!
I always thought measurement to any given object was expressed in terms of where the object APPEARED to be.
Very interesting question!
You get a star!

Answer 2

Well, a million years is still in our local part of the Universe and here we don't really need to concern ourselves about the effects of the expansion of the Universe. Things in our local Universe almost all move at less than 1,000 kilometers a second, which is less than 1/300 of the speed of light., and so their current distance would be still between 997,000 light years and 1,003,000 light years from us. And we would have to know the speed of motion of the star to accurately determine it. So, we just use the distance it had when the light was emitted.

But if we look out to the edge of the visible universe, then we see things as they were about 13 billion years ago when they were receding from us at almost the speed of light. Those distant galaxies would now be 26 billion light years away. But, given that the expansion of the Universe seems to be accelerating, they will be even farther than that from us. Since the calculation of the exact current distance depends on the model of expansion used, we normally don't concern ourselves with it. We just go by the distance at the time it emitted the light we are now seeing.

Answer 3

What I think you're referring to is known as the "co-moving distance" which is the calculated "actual distance right now" of the star. You basically need to factor in the expansion of the universe and how long the object has been in existence to arrive at a value.

Answer 4

They are not. What we are seeing is reality as well as we can know it. When you look at a friend who is standing a foot away, you actually see him as he was a tiny fraction of a second different from his actual position. You do not correct for that, nor do we correct for the position of the planets, unless we are traveling to them and need to account for the difference in trajectories so we meet in the middle (ADDED: and in that case, we are making the assumption that the planet will move predictably and will still be there when we get there. For distant stars, this may not be an accurate assumption). We see them as we can see them - in our present timeline. The problem is that time and space are inseparably linked - they cannot be unraveled.