Electromagnetic Radiation

  • Generated by processes at the atomic level
    • Changes in the way parts of an atom interact and move
  • Forms of electromagnetic radiation are described by the electromagnetic spectrum
  • Low energy --> low frequency
  • High energy --> high frequency
  • Particles are photons
  • Types of radiation emitted by astronomical objects is determined by their temperature
Type of RadiationWavelength Range (nm)Radiated by Objects at This TemperatureTypical Sources
Gamma RaysLess than 0.01More than $10^8$ KNuclear reactions
X-rays0.01-20$10^6-10^8$ KGas clusters in galaxies, supernova remnants, solar corona
Ultraviolet Rays20-400$10^4-10^6$ KSupernova remnants, very hot stars
Visible light400-700$10^3-10^4$ KStars
Infrared$10^3-10^6$$10-10^3$ KCool clouds of dust and gas, planets, moons
Microwaves$10^6-10^9$Less than 10 KActive galaxies, pulsars, cosmic background radiation
Radio WavesMore than $10^9$Less than 10 KSupernova remnants, pulsars, cold gas

Physics Electromagnetic Spectrum