The luminous streak lasting seconds or fractions of a second and seen at night when a solid, natural body plunges into the Earth's (or another planet's) atmosphere. The entering object is called a meteoroid and, if any of it survives atmospheric passage, the remainder is called a meteorite. Cosmic dust particles (with masses of micrograms) entering the atmosphere and leaving very brief, faint trails are called micrometeors, with the surviving pieces known as micrometeorites. If the apparent brightness of a meteor exceeds that of the planet Venus as seen from Earth, it is called a fireball; and when a bright meteor is seen to explode, it is called a bolide.