The discussion revolves around the implications of observing astronomical events that occurred in the past, specifically focusing on the time it takes for light from distant objects to reach Earth. Participants explore the concept of light years and how distance affects our perception of time in space, with references to specific astronomical examples.
Participants generally agree on the principle that we see distant astronomical events as they were in the past, depending on their distance from Earth. However, there is no consensus on the significance of the specific time frame of 350 million years, and some participants question its relevance.
The discussion touches on the complexities of defining distances in space and the effects of cosmic expansion on light travel time, which remain unresolved and may depend on specific conditions or definitions.
TaurusSteve said:Summary:: Light Years.
If something happened 350 million years ago in space, are we just seeing it/ receiving the light now?
Ok, but I mean much further away. Say Andromeda.PeroK said:Not if it happened 5 light years away.
TaurusSteve said:Ok, but I mean much further away. Say Andromeda.
Ok the figure is irrelevant lol. We would see the target as it was all those years ago?PeroK said:Why 350 million years ago? Why not 2 million years ago (or thereabouts)?
TaurusSteve said:Ok the figure is irrelevant lol. We would see the target as it was all those years ago?
Unless it was 350MLY away, the light would have gone past us ages ago. We have missed it! Someone may have spotted it and written down the event - but only within the past few centuries, for most notable events.TaurusSteve said:Summary:: Light Years.
If something happened 350 million years ago in space, are we just seeing it/ receiving the light now?
This is what I meant! These mindblowing facts!PeroK said:If something is 2 million light years away - let's say a supernova - then it takes, by definition, 2 million years for the light to reach us.
For example, Betelgeuse is about 700 light years away and there is speculation that it is about to go supernova. But, if we see it going supernova this year, then it actually happened about 700 years ago.
This is just an extension of the fact that a light signal from the Moon takes over a second to reach Earth - so we are seeing the Moon as it was one second ago. Light from the Sun takes 8 minutes; light from the Pole star about 400 years etc.
If you go far enough then the spatial expansion of the universe becomes an additional factor, which complicates the calculations.