Observing the Universe
Arbennig | A | B | C | CH | D | DD | E | F | FF | G | NG | H | I | L | LL | M | N | O | P | PH | R | RH | S | T | TH | U | W | Y | Y CYFAN
A
Absorption spectrumA spectrum containing dark lines where specific wavelengths have been absorbed by a cooler gas. | |
Astronomical UnitThe average distance between the Earth and the Sun (about 150 million kilometres). | |
C
Continuous spectrumA spectrum containing all wavelengths without interruption. | |
D
Diffraction gratingAn optical device that separates light into its component wavelengths. | |
E
Electromagnetic spectrumThe complete range of electromagnetic radiation, arranged by wavelength or frequency. | |
Emission spectrumA spectrum containing bright lines produced by excited atoms or ions. | |
G
GalaxyA massive collection of stars, gas, dust, planets, and dark matter held together by gravity. | |
Galaxy ClusterA group of galaxies bound together by gravity. | |
Gamma raysThe highest-energy electromagnetic waves with the shortest wavelengths. | |
I
Infrared radiationElectromagnetic radiation with wavelengths longer than visible light, often emitted by cooler objects. | |