
Space observatory
A space observatory is any
instrument in outer space
which is used for
observation of distant
planets, galaxies, and other
outer space objects. A large
number of observatories have
been launched into orbit,
... > full story

Astrophysics
Astrophysics is the branch
of astronomy that deals with
the physics of the universe,
including the physical
properties (luminosity,
density, temperature and
chemical composition) of
astronomical objects such as
... > full story

Orion Nebula
The Orion Nebula (also known
as Messier 42, M42, or NGC
1976) is a glowing emission
nebula with a greenish hue
and is situated below
Orion's Belt. It is one of
the brightest nebulae
visible to the naked eye in
... > full story

Galaxy formation and evolution
The formation of galaxies is
still one of the most active
research areas in
astrophysics; and, to some
extent, this is also true
for galaxy evolution. Some
ideas, however, are now
... > full story
Browse Reference Articles
1 to 10 of 194 articles
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Supergiant
Supergiants are the most massive stars. Supergiants can have masses from 10 to 70 solar masses and brightness from 30,000 up to hundreds of thousands times the solar luminosity. They vary greatly in ... > more -
Cepheid variable
A Cepheid variable or Cepheid is a member of a particular class of variable stars, notable for a fairly tight correlation between their period of variability and absolute luminosity. Since the ... > 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 -
Star cluster
Star clusters are groups of stars which are gravitationally bound. Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old ... > 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 -
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 -
Spitzer Space Telescope
Spitzer Space Telescope (formerly the Space Infrared Telescope Facility [SIRTF]) is an infrared space observatory, the fourth and final of NASA's Great Observatories. The first images taken by SST ... > more -
Radio telescope
A radio telescope is a form of radio receiver used in astronomy. In contrast to an "ordinary" telescope, which receives visible light, a radio telescope "sees" radio waves emitted by radio sources, ... > more -
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a band of bright stars emerging from the center and running across the middle of the ... > more
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