Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are smaller than planets but larger than meteoroids
A comet is a relatively small Solar System body. Comet nuclei are loose collections of ice, dust, and small rocky particles, ranging from a few hundred meters to tens of kilometers across
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface.Meteorites can be big or small.
The largest asteroid ever to hit Earth was probably Theia, a Mars-sized body that formed over 4 billion years ago, during the early days of the solar system. Theia formed in a Lagrange point, a gravitationally stable region in the Earth's orbit, located on the opposite side of the Sun. Eventually, orbital fluctuations caused this body to oscillate closer and closer to the Earth, and eventually, they collided, throwing up a greater volume of molten rock than all the present-day continents combined. Some of this molten rock was ejected so forcefully that it entered orbit, aggregated, cooled, and became our Moon. This scenario is called Giant Impact Theory, and it accurately explains most features of the Earth-Moon system, such as why the chemical composition of the Moon is similar to that of the Earth's crust.
Armageddon is a film about an asteroid that hits the earth. After New York City is damaged by hundreds of small meteorites, NASA discovers an asteroid the size of Texas is on a collision course with Earth. They recruit the best deep core driller in the world, Harry Stamper, to train astronauts who will go to the asteroid, drill into the center and detonate a nuclear warhead. Harry says he can't train men how to drill in ten days, so he brings in his own team of roughnecks to learn to become astronauts and get the job done. One of his team is the fiancé of his own daughte