Meteor and meteoroid
Meteoroids are small rocky or metallic bodies exist in the outer space and move around the sun. When a meteoroid accidently enters in the earth atmosphere, it is crashed and a streak of light is produced. This streak of light is called meteor.
Atmosphere is a layer of gases surrounded by a planet. Particles of these gases are retained by the planet by the gravitational force of the planet.
Earth’s atmosphere consists mostly of nitrogen and oxygen.