Reference Terms
from Wikipedia, the free encyclopedia
Planet
The International Astronomical Union defines "planet" as a celestial body that, within the Solar System that is in orbit around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape; and has cleared the neighbourhood around its orbit; or within another system, it is in orbit around a star or stellar remnants; has a mass below the limiting mass for thermonuclear fusion of deuterium; and is above the minimum mass/size requirement for planetary status in the Solar System.
Note: The above text is excerpted from the Wikipedia article "Planet", which has been released under the GNU Free Documentation License.
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Space & Time News
May 11, 2025
May 8, 2025 — In space, energetic neutrinos are usually paired with energetic gamma rays. Galaxy NGC 1068, however, emits strong neutrinos and weak gamma rays, which presents a puzzle for scientists to solve. A new paper posits that helium nuclei collide with ...
May 7, 2025 — Magnetar flares, colossal cosmic explosions, may be directly responsible for the creation and distribution of heavy elements across the universe, suggests a new ...
Apr. 28, 2025 — Astrophysicists have discovered a potentially star-forming cloud that is one of the largest single structures in the sky and among the closest to the sun and Earth ever to be detected. The scientists have named the molecular hydrogen cloud 'Eos,' ...
Apr. 25, 2025 — Astronomers have discovered that super-Earth exoplanets are more common across the universe than previously thought. While it can be relatively easy to locate worlds that orbit close to their star, planets with wider paths can be difficult to ...
Latest Headlines
updated 12:56 pm ET
May 9, 2025 — Researchers have developed an innovative photodetector capable of detecting a broad range of mid-infrared ...
May 9, 2025 — A research team used the German environmental satellite EnMAP (Environmental Mapping and Analysis Program) to simultaneously detect the two key air ...
May 8, 2025 — A long period of drought in North America has been recognized by scientists for decades. A new study links the severe climate to a change in Earth's ...
May 6, 2025 — In the quest toward finding the correct theory of quantum gravity, physicists have been testing the holographic principle which, they say, is a key property of any valid theory of quantum ...
May 6, 2025 — Astronomers have probed the physical environment of repeating X-ray outbursts near monster black holes thanks to data from NASA's NICER (Neutron star Interior Composition Explorer) and other ...
May 6, 2025 — Neutrinos and antineutrinos are elementary particles with small but unknown mass. High-precision atomic mass measurements have revealed that beta ...
May 5, 2025 — Researchers have developed a new quantum theory of gravity which describes gravity in a way that's compatible with the Standard Model of particle ...
May 5, 2025 — In 1959, physicists James Terrell and Roger Penrose (Nobel laureate in 2020) independently concluded that fast-moving objects should appear rotated. However, this effect has never been demonstrated. ...
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May 1, 2025 — The European Space Agency's Gaia mission has spotted an unusual family of stars all strangely eager to leave home -- a family we couldn't have discovered without the star-surveying spacecraft, and ...