Question

Why have astronomers decided that pluto should be reclassified as a dwarf planet?

what happens to most meteors when they enter earth's atmosphere?

Answer 1

There is a new standard of planets that the IAU set in 2006 and Pluto did not pass it. The new qualification is that a planet must be free of debris around it.

Most meteors are small enough to be burned by friction once it enters the Earth's atmosphere. They are also called 'shooting stars'.