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
February 20, 2025
'Out of Science Fiction': First 3D Observations of an Exoplanet's Atmosphere Reveal a Unique Climate
Feb. 18, 2025 — Astronomers have peered through the atmosphere of a planet beyond the Solar System, mapping its 3D structure for the first time. By combining all four telescope units of the European Southern ...
Feb. 13, 2025 — What if time is not as fixed as we thought? Imagine that instead of flowing in one direction -- from past to future -- time could flow forward or backward due to processes taking place at the quantum ...
Feb. 12, 2025 — Scientists have just detected a neutrino that is thirty times more energetic than any previously detected anywhere in the world. This exceptional discovery opens up new perspectives for understanding extreme energy phenomena in the Universe and the ...
Feb. 10, 2025 — Euclid, the European Space Agency's dark Universe detective, has made an astonishing discovery -- right in our cosmic ...
Latest Headlines
updated 12:56 pm ET
Feb. 20, 2025 — An international research collaboration has overturned the long-standing belief that the atomic nucleus of lead-208 is perfectly spherical. The ...
Feb. 20, 2025 — Researchers have found that stars in the early universe may have formed from 'fluffy' molecular clouds. Using the ALMA telescope to observe the Small Magellanic Cloud -- whose environment is similar ...
Feb. 19, 2025 — Within the Dark Energy Spectroscopic Instrument's early data, scientists have uncovered the largest samples ever of intermediate-mass black holes and ...
Feb. 18, 2025 — Astrophysicists have observed our central supermassive black hole. They found the accretion disk is constantly emitting flares without periods of ...
Feb. 18, 2025 — Lobster-eye satellite Einstein Probe captured the X-ray flash from a very elusive celestial pair. The discovery opens a new way to explore how massive stars interact and evolve, confirming the unique ...
Feb. 14, 2025 — Researchers demonstrated the first fully 3D-printed, droplet-emitting electrospray engine. The low-cost device can be fabricated more quickly than traditional thrusters, potentially from on board a ...
Feb. 14, 2025 — Asteroids that orbit close to the Earth inevitably cause us some anxiety due to the even remote possibility of a collision. But their proximity also ...
Feb. 14, 2025 — As more satellites, telescopes, and other spacecraft are built to be repairable, it will take reliable trajectories for service spacecraft to reach ...
Feb. 13, 2025 — Traditional black holes, as predicted by Albert Einstein's theory of General Relativity, contain what are known as singularities, i.e. points where the laws of physics break down. Identifying how ...
Feb. 13, 2025 — Astronomers used a 3D global computer model to compare the climates of exoplanets in different stellar and orbital configurations. They found that a planet orbiting a white dwarf star would offer a ...