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
April 29, 2025
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 ...
Apr. 17, 2025 — Research from NASA's Curiosity rover has found evidence of a carbon cycle on ancient ...
Apr. 16, 2025 — Astronomers have detected the most promising signs yet of a possible biosignature outside the solar system, although they remain ...
Latest Headlines
updated 12:56 pm ET
Apr. 28, 2025 — The NASA New Horizons spacecraft's extensive observations of Lyman-alpha emissions have resulted in the first-ever map from the galaxy at this ...
Apr. 28, 2025 — For decades, scientists believed Vesta, one of the largest objects in our solar system's asteroid belt, wasn't just an asteroid and eventually concluded it was more like a planet with a crust, mantle ...
Apr. 28, 2025 — New research has revealed that a massive meteorite struck northwestern Scotland about 200 million years later than previously thought, in a discovery that not only rewrites Scotland's geological ...
Apr. 18, 2025 — Researchers use the sophisticated technology on NASA's Perseverance rover to analyze volcanic rocks in Mars' Jezero Crater. Their findings show that some of the same volcanic processes that led to ...
Apr. 24, 2025 — The world's largest solar telescope has reached an important milestone. The data published now were obtained during the technical commissioning of the ...
Apr. 24, 2025 — Carbon-containing meteorites look like they had less severe impacts than those without carbon because the evidence was blasted into space by gases ...
Apr. 24, 2025 — Using the James Webb Space Telescope (JWST), scientists analyzed far-away bodies -- known as Trans-Neptunian Objects (TNOs) -- and found varying ...
Apr. 23, 2025 — Scientists and space explorers have been on the hunt to determine where and how much ice is present on the Moon. Water ice would be an important resource at a future lunar base, as it could be used ...
Apr. 22, 2025 — A planet 140 light-years from Earth is rapidly coming apart due to its close proximity to its star. The roasting planet is effectively evaporating ...
Apr. 21, 2025 — Geologists weigh in on a long-running debate about Mars: Billions of years ago, was the Red Planet warm and wet or cold and ...