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Globular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and ... > more -
Planetary nebula
A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. They are in fact unrelated to planets; the ... > more -
Dark matter
In astrophysics and cosmology, dark matter is hypothetical matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, but whose presence can ... > more -
Stellar classification
In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral ... > more -
Interstellar medium
The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space. Whilst the ISM refers to the matter (interstellar matter, also abbreviated ... > more -
Physical cosmology
Physical cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. Cosmology ... > more -
Edwin Hubble
Edwin Powell Hubble (November 20, 1889 - September 28, 1953) was an American astronomer, noted for his discovery of galaxies beyond the Milky Way and the cosmological redshift. Edwin Hubble was one ... > more -
Red supergiant
Red supergiants are supergiant stars of spectral type K-M and a luminosity class of I. They are the largest stars in the universe in terms of physical size, although they are not the most massive. ... > more -
Black hole
A black hole is a concentration of mass great enough that the force of gravity prevents anything from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). The ... > more -
Gamma ray burst
Gamma-ray bursts are the most luminous physical phenomena in the universe known to the field of astronomy. They consist of flashes of gamma rays that last from seconds to hours, the longer ones being ... > more
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