This page is meant to make it easier for you to understand the content of this web site. The glossary contains both astronomical and art terms.
Radiation: Radiation is a form of energy, whether as light or as a wave. Link: Fusion processes and radiation.
Radiation pressure: The pressure exerted by radiation.
Radiative zone: The zone in a star's interior in which energy is mostly transferred through radiation. The other zone is called the convective zone.
Red giant: A star with low surface temperature (thus red) and large size (supergiant). These stars are found on the upper-right hand side of the H-R diagram. The red giant phase in a star's life occurs after it has left the main sequence. The Sun will become a red giant in about 5 billion years.
Reflection Nebula: A nebula composed of dust particles that scatter and reflect incident light (rather than glowing from their own intrinsic emission). Dust preferentially scatters short wavelengths, so reflection nebulae have a characteristic blue appearance.
Roche lobe: The region surrounding a star in a binary system inside of which the star's material is gravitationally bound to the star. Two binary stars that share a Roche lobe constitute a contact binary.
RR Lyrae Variables: A variable star that has a regularly varying luminosity. These stars all have about the same luminosity making them suitable for obtaining distances. They are not as useful as Cepheid variables, however, because they are not as luminous. Link: RR Lyrae.
A B C D E
F G H I J
K L M N O
P Q R S T
U V W X Y