Pick a destination. Guess how long light takes. Then get roasted by the universe.
Pick a destination, guess how long it takes, then see how close you were.
Light moves at 299,792 km/s. When Mars is closest to Earth — during opposition, about every 26 months — the distance is roughly 54.6 million kilometers. That means a radio signal takes about 3 minutes and 2 seconds. When Mars is on the opposite side of the Sun, the delay stretches to over 22 minutes.
This is why NASA's Perseverance rover had to be completely autonomous. There's no real-time remote control possible. If the rover hit a rock, the signal would take 12 minutes to reach Earth, and another 12 for the command to come back. The rover has to decide for itself.
Alpha Centauri, the nearest star system, is 4.37 light-years away. The light you see tonight left that star system before you graduated high school. If an alien there had a powerful telescope watching Earth, they'd be watching the year 2022 right now.
When Mars is closest (~55 million km), light takes ~3 minutes. At farthest (~400 million km), ~22 minutes.
One light-year is the distance light travels in a year: ~9.46 trillion km. Alpha Centauri is 4.3 light-years away.
When you look at stars, you see them as they were years ago. Light from the Andromeda Galaxy left 2.5 million years ago.