- #1
Adamchiv
- 48
- 9
Hi, I am new to this forum and I signed up because I am having difficulty working something out. I am no expert whatsoever when it comes to astrophysics so please be kind.
We can measure the distance of galaxies using the speed of light, so we know that a galaxy 8 billion light years away for example has already moved further away by the time we have seen it, also we are looking at it as it was 8 billion years ago. I don't have any issue with this.
My problem is Andromeda, it is 2.537 million light years away and moving towards us at a rate of about 68 miles per second. So we are ofcourse looking at it as it was 2.537 million years ago, but if that is the case and its moving towards us, surely it must be closer than that. If we look at something in the past that began moving towards is it must be closer to us in the present, because we are now 2.537 million years further into the future than the time in which we percieve it, or receive the photons immited from it. Also surely on that premise, if it is closer to us than we percieve it to be, then surely we would be able to see it as closer? How can we look at something in the past that's moving towards us and not be able to percieve it as closer than it was 2.537 million years ago? because that was ofcourse in the past and not the present. Its almost like if I were to throw a ball to you and your reactions were so slow that you were 3 seconds behind, by the time you see the ball thrown it has already hit you
Hope it makes sense and apologies if its a silly question
Adam
We can measure the distance of galaxies using the speed of light, so we know that a galaxy 8 billion light years away for example has already moved further away by the time we have seen it, also we are looking at it as it was 8 billion years ago. I don't have any issue with this.
My problem is Andromeda, it is 2.537 million light years away and moving towards us at a rate of about 68 miles per second. So we are ofcourse looking at it as it was 2.537 million years ago, but if that is the case and its moving towards us, surely it must be closer than that. If we look at something in the past that began moving towards is it must be closer to us in the present, because we are now 2.537 million years further into the future than the time in which we percieve it, or receive the photons immited from it. Also surely on that premise, if it is closer to us than we percieve it to be, then surely we would be able to see it as closer? How can we look at something in the past that's moving towards us and not be able to percieve it as closer than it was 2.537 million years ago? because that was ofcourse in the past and not the present. Its almost like if I were to throw a ball to you and your reactions were so slow that you were 3 seconds behind, by the time you see the ball thrown it has already hit you
Hope it makes sense and apologies if its a silly question
Adam