Solar energy is the energy given off by the sun. When light energy is absorbed by objects it is changed to heat energy. Dark-colored objects absorb more light and store more heat from sunlight.
Solar energy is produced by nuclear fusion reactions within the sun.
Solar energy does not pollute. Light-colored objects appear light to us because they are reflecting most of the light that hits them rather than absorbing it. Objects appear to be black when they absorb all wavelengths of light that hit them. Use your thermometer to see what temperature it is outside. If it isn't hot enough outside, wait for a warmer day.