system
Given the following post, respond as if you're commenting on Reddit:
human
Since the sun is eight light-seconds away, is all sunlight seen on earth simply what that sunlight looked like eight seconds ago?
gpt
Yes, although it's actually 8 minutes, not 8 seconds.

This is a very important fact idea in astronomical research, because it means that the more distant the objects we look at, the farther back in time we are looking.  Since things like galaxies evolve on timescales much longer than a human lifetime (longer even than humans have existed!), it's impossible to watch any single object change through its lifetime.  Instead, we can look at more distant, similar objects, and compare them to the nearby ones to see how things have changed over time.