Stars produce their own light but planets do not. even then we can see them. explain

Planets are not hot enough, and that's because they lack the internal energy sources that stars have: thermonuclear fusion (They do emit a little light, mainly infrared light, but nothing compared to the sun)

Planets don't have their own light, so simply they do not emit light, this phenomena goes back to their information. When they are formed, they are much, much less hotter than the stars. In stars, fusion reaction always goes on, in which energy, as well as light is formed, so, there is light for stars to emit for a long time.

Distance^2= yellow line ^2 (see picture) = 30^2 + 49^2so distance = squareroot of (300^2 +49^2)i dont know if this is how to solve it, but i cnt think of another way