A meteor is

1. A meteor, commonly known as a 'shooting star', is the visible streak of light produced when a meteoroid enters the Earth's atmosphere and burns up due to friction. 2. A meteoroid is a small rocky or metallic body travelling through outer space. It is significantly smaller than an asteroid. 3. Therefore, a meteor is essentially a piece of matter (a meteoroid) from outer space that has entered the Earth's atmosphere. 4. Option (A) is incorrect; stars are distant celestial bodies, not rapidly moving objects entering our atmosphere. 5. Option (C) is incorrect; a constellation is a group of stars forming a pattern. 6. Option (D) is incorrect; a comet is an icy body that develops a tail as it approaches the sun, and a meteoroid is distinct from a comet.