Astronomy terms starting with R

11 terms

  1. Radiation (RAY-dee-AY-shun) Energy released in the form of particle or electromagnetic waves.
  2. Radiation Belt Magnetized planets, like Earth, are encircled by zones of particle radiation known as the "Van Allen belts," in which high-energy charged particles spiral…
  3. Radiation Gas A mixture of photons and fast-moving charged particles.
  4. Radiation-Dominated Universe When the density of radiation is greater than that of any other component.
  5. Radiative Zone A layer of the Sun lying between the core and convection zone where en­ergy travels outward through the slow radiation, absorption, and re-radiation of…
  6. Radio Waves Electromagnetic radiation with a wavelength greater than 1 mm (beyond infrared).
  7. Recede To move away from the observer, which is, in most cosmological instances, the earth.
  8. Redshift A change in the frequency or wavelength of light. This can arise from motion of the source (Doppler shift), expansion of space, or strong gravitational…
  9. Relative Brightness How bright one object is compared to another. If they have the same intrinsic brightness then the relative brightness tells us the ratio of distances to…
  10. Relativity Galileo first developed the principle of relativity, being the postulate that the laws of physics should take the same form for all observers in uniform…
  11. Relic Some thing left over from a previous time period. Remnant products or evidence of early physical eras.