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.
Our solar system is thus considered to have eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Under a separate resolution, it is also considered to have three dwarf planets: Ceres, Pluto, and Eris. There have been more than two hundred planets discovered orbiting other stars to date.
Related Stories
1
2
Space & Time News
August 21, 2025
Aug. 18, 2025 — NASA and ISRO s NISAR satellite has just reached a major milestone: the successful deployment of its enormous 39-foot antenna reflector in orbit. Folded up like an umbrella during launch, the reflector is now fully extended and ready to support ...
Aug. 18, 2025 — With its two tiny CubeSats, NASA’s PREFIRE mission is capturing invisible heat escaping from Earth, offering clues to how ice, clouds, and storms influence the climate system. The insights could lead to better weather forecasts and a deeper ...
Aug. 17, 2025 — Rising CO₂ levels will make the upper atmosphere colder and thinner, altering how geomagnetic storms impact satellites. Future storms could cause sharper density spikes despite lower overall density, increasing drag-related ...
Aug. 14, 2025 — Thirteen years after landing on Mars, NASA’s Curiosity rover is running smarter and more efficiently than ever. With new autonomy and multitasking capabilities, it’s maximizing the output from its long-lasting nuclear power source while ...
July 27, 2025 — Engineers at the University of Wisconsin-Madison uncovered a critical flaw in how lunar and Martian rovers are tested on Earth. Simulations revealed that test results have been misleading for decades because researchers only adjusted rover weight to ...
July 2, 2025 — UF engineers, backed by DARPA and NASA, are perfecting laser-forming techniques that let metal sheets fold themselves into giant solar arrays, antennas, and even space-station parts right in ...
June 27, 2025 — The LSST camera at the Vera C. Rubin Observatory has released its jaw-dropping first images, each capturing 45 times the area of the full moon in one shot. Over the next ten years, this cosmic giant will scan the southern sky in ultra-HD, helping ...
June 25, 2025 — Imagine printing your Martian home from dust, sunlight, and a bit of biology. A new synthetic lichen system uses fungi and bacteria to grow building materials directly from Martian soil, completely autonomously and without human ...
June 24, 2025 — Lichen from the Mojave Desert has stunned scientists by surviving months of lethal UVC radiation, suggesting life could exist on distant planets orbiting volatile stars. The secret? A microscopic “sunscreen” layer that protects their vital ...
June 15, 2025 — AI has helped astronomers crack open some of the universe s best-kept secrets by analyzing massive datasets about black holes. Using over 12 million simulations powered by high-throughput computing, scientists discovered that the Milky Way's central ...
June 11, 2025 — By using a clever quantum approach that involves two "hands" on a clock one moving quickly and invisibly in the quantum world, the other more traditionally scientists have found a way to boost timekeeping precision dramatically. Even better, this ...
June 5, 2025 — Supermassive black holes might naturally replicate the colossal energies of man-made particle colliders possibly even revealing dark matter offering a cosmic shortcut to discoveries that would ...
Latest Headlines
updated 12:56 pm ET
Aug. 21, 2025 — A giant bubble of gas and dust surrounds the red supergiant DFK 52, likely created in a powerful outburst 4,000 years ago. Astronomers are baffled at how the star survived without going supernova, ...
Aug. 21, 2025 — Scientists from the Southwest Research Institute have found strong evidence that near-Earth asteroids Bennu and Ryugu share a common origin with Polana, a much larger asteroid in the main belt. By ...
Aug. 21, 2025 — Astronomers using the James Webb Space Telescope have uncovered a tiny new moon orbiting Uranus, increasing the planet’s moon tally to 29. The object, only about six miles wide, escaped Voyager ...
Aug. 21, 2025 — Scientists have identified a never-before-seen supernova, SN2021yfj, which exploded after losing nearly all of its outer layers. Instead of light elements, it revealed silicon and sulfur from deep ...
Aug. 21, 2025 — Massive stars have always puzzled scientists—how do they grow so quickly despite fierce radiation pushing material away? New high-resolution ALMA observations suggest that instead of relying solely ...
Aug. 20, 2025 — Hubble’s newest view of the spiral galaxy NGC 2835 adds a stunning twist to a familiar sight. By capturing light in a special wavelength called H-alpha, astronomers have revealed glowing pink ...
Aug. 20, 2025 — NASA’s Parker Solar Probe has directly observed magnetic reconnection in the Sun’s atmosphere for the first time, confirming decades-old theories about solar explosions. This discovery bridges ...
Aug. 19, 2025 — A mysterious blazar that baffled scientists for years has been unraveled. VLBA imaging revealed a toroidal magnetic field powering a jet aimed at Earth, explaining how it can unleash neutrinos and ...
Aug. 19, 2025 — Hubble has taken the clearest image to date of the interstellar comet 3I/ATLAS, which is racing through our solar system at 130,000 miles per hour. Astronomers are using Hubble and other telescopes ...
Aug. 19, 2025 — For decades, scientists have puzzled over why so little sulfur appears in space, even though it is one of the most common elements in the universe and vital to life. A new study suggests that the ...