Glossaire beginning with R
- Radiation pressure
Repulsive force exerted on an illuminated side of a solid, due to the transfer of part of the momentum of incident photons. It is it which, repelling the dust ejected by the comet nucleus, form their principal tail.
- Radio astronomy
- Branch of astronomy studying the radio emission of celestial objects. The Sun, planets, comets, some stars, the atomic, molecular or ionized interstellar gas, high-energy cosmic ray electrons, pulsars, galaxies, quasars, etc. emit radio waves.
- Radio telescope
- Antenna or set of antennas for radio astronomy.
- Motion of a planet or comet around the Sun, or of a satellite around its planet.
- Motion of a star, a planet, a satellite or a comet nucleus around its axis.