Light pollution<span> is excessive and inappropriate artificial </span>light<span>. The four components of </span>light pollution<span>are often combined and may overlap: Urban Sky Glow—the brightening of the night sky over inhabited areas. </span>Light<span> Trespass—</span>light<span> falling where it is not intended, wanted, or needed.</span>
I could be wrong, but I believe that light pollution is when there is too much light around, that kinda "blinds" us from seeing the stars, or that it "blocks out" the light from the stars far away. This prevents astronomers from looking at the sky and studying the stars. However, they could be able to study them if they look into a telescope, I'm not sure. I know my answer isn't that good, but I hope you get an idea from it, or that someone agrees with me... ? :D Good Luck!