Glossaire beginning with M
Upper region of the upper atmosphere, characterized by relatively high-energy, charged particles trapped in the Earth's magnetic field. Jupiter and Saturn also have a magnetosphere.
- Meridian (celestial)
- Great circle passing through the two celestial poles.
- Solid body belonging to the Solar system, which can sometimes fall on the Earth. Meteorites are very primitive rocks; the carbonaceous chondrites are the most interesting ones to understand the formation of the Solar system.
- Assembly of several atoms.