How long does it take for starlight to reach the earth?

If the distance between the planet and the earth you see is in light years, then the distance is several light years, and the light from it will take several years to reach the earth. For example, the distance between Altair and the earth is 16 light years, and it takes 16 years for the light emitted by Altair to reach the earth. In other words, the Altair we saw on the night of July 7th was actually the Altair before 16. The so-called light year is a unit of distance. In astronomy, the distance traveled by light in one year is used as the basic unit of length.

If the distance between the planet you see and the earth is not in light years, then divide this distance by 30000000000 m/s, for example, the time for sunlight to reach the earth is 8 minutes.