Glossary

This glossary covers words that you will come across on this website.

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Click one of the letters above to be taken to a page of all terms beginning with that letter.

Radiation: Energy in the form of waves or moving sub-atomic particles emitted by an atom or other body as it changes between energy states. Radiation can be classified as ionizing or non-ionizing, depending on its effect on atomic matter.
Recessional velocity: A term used to describe the rate at which an object is moving away, typically from Earth. This term is enerally applied in reference to distant Galaxies.
Synonyms:
Redshift: When electromagnetic radiation emmitied or reflected by an object is shifted towards the less energetic (red) end of the spectrum. This is known as the Doppler Effect. Redshift is also defined as an increase in the wavelength of E-M radiation corresponding to a drop in frequency. A decrease in wavelength is called ' Blueshift '.