1. The right answer is meteor.
In a more restricted sense, a meteor refers to the luminous drag produced by the entry into the atmosphere of an extraterrestrial body, or meteoroid, which can produce, if it has not been entirely consumed, one or more meteorites. There are two types:
* The shooting star, produced by a small meteoroid (typically less than a millimeter in size, like a grain of sand), which volatilizes entirely in a fraction of a second at altitudes above 100 km. Among the sources of shooting stars, the comets leave in their orbit, a number of cometary grains; when the Earth crosses the cloud of dust formed by this trace, a swarm of meteors occurs. These crossings take place annually with a relatively fixed period
* A large meteoroid often estimated centimeter to decimetric before entering the atmosphere. For such diameters, the object volatilizes almost entirely, if not a few microscopic grains which end in free fall. Larger objects, all the rarer because they are large, often break up when they arrive in the dense layers of the atmosphere, around 70-50 km above sea level. From 50 to 30 km altitude, the fragments simply fall in free fall, at a slower speed, and the luminous phenomenon, the "meteor" proper, disappears: it is the dark flight, which makes the search delicate meteorites - the various shearing winds encountered, as well as their aerodynamically singular shapes, cause a dispersion of the trajectories with respect to the meteoric drag. These big meteoroids are the focal point of the FRIPON research program.
2. The right answer is meteorites.
The meteorites are rocky bodies of extraterrestrial origin that survived the crossing of the atmosphere and found on the ground. It is thought that an immense meteorite (several kilometers in diameter) was responsible for the disappearance of the dinosaurs, 65 million years ago. It is estimated that 10,000 metric tons of micrometeorites and meteorites fall on Earth per year.
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