Comets are blocks of frozen ice mixed with cosmic dust. It is estimated there to be a trillion more comets on the edge of the solar system. When a comet goes by the sun it transforms from a sold form to gases. Also the tail of a comet faces a way from the sun at all times. The most famous comet is Halleys Comet.
Fire balls are large meteors that pass close to Earth.
More than 2000 meteors are known. A great many enter the Earth's atmosphere each day, maybe as many as 100 million. My experience with the project was all I expected it to be. Doing this project has been good. I learned a lot.