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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 -
Presentism (philosophy of time)
In the philosophy of time, presentism is the belief that neither the future nor the past exists. The opposite of presentism is 'eternalism', which is a belief in things that are past and things that ... > more -
Model rocket
Model rocketry is a hobby similar to building model airplanes. In the hobby today, there are two distinct areas of rocket activity: amateur (or experimental) rocketry, and model rocketry (including ... > more -
Saturn's natural satellites
Saturn is currently known to have 56 moons, many of which were discovered very recently, and 3 additional un-confirmed, hypothetical moons. However, a precise number of moons can never be given, as ... > more -
Van Allen radiation belt
The Van Allen radiation belt is a torus of energetic charged particles (i.e. a plasma) around Earth, trapped by Earth's magnetic field. When the belts "overload", particles strike the upper ... > more -
Lunar space elevator
A lunar space elevator (also called a moonstalk) is a proposed cable running from the surface of the Moon into space. It is similar in concept to the better known Earth space elevator idea (a cable ... > more -
Mars Exploration Rover
NASA's Mars Exploration Rover (MER) Mission is an unmanned Mars exploration mission that sent two robotic rovers Spirit and Opportunity to explore the Martian surface and geology. Primary among the ... > more -
Local Group
The Local Group (also called M31 group or the Andromeda group) is the group of galaxies that includes our galaxy, the Milky Way. The group comprises over 30 galaxies, with its gravitational center ... > more
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