Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid
These are organized by a classification scheme developed exclusively for Cosma. More…
Neptune : the planet eighth in order from the sun — Webster
Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune. Neptune orbits the Sun once every 164.8 years at an average distance of 30.1 astronomical units (4.50×109 km). It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune’s trident.
Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. Neptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier. Its largest moon, Triton, was discovered shortly thereafter, though none of the planet’s remaining known 14 moons were located telescopically until the 20th century. The planet’s distance from Earth gives it a very small apparent size, making it challenging to study with Earth-based telescopes. Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989. The advent of the Hubble Space Telescope and large ground-based telescopes with adaptive optics has recently allowed for additional detailed observations from afar.
Neptune’s composition can be compared and contrasted with the Solar System’s other giant planets. Like Jupiter and Saturn, Neptune’s atmosphere is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen, but it contains a higher proportion of “ices” such as water, ammonia, and methane. However, its interior, like that of Uranus, is primarily composed of ices and rock, which is why Uranus and Neptune are normally considered “ice giants” to emphasise this distinction. Traces of methane in the outermost regions in part account for the planet’s blue appearance.
In contrast to the hazy, relatively featureless atmosphere of Uranus, Neptune’s atmosphere has active and visible weather patterns. For example, at the time of the Voyager 2 flyby in 1989, the planet’s southern hemisphere had a Great Dark Spot comparable to the Great Red Spot on Jupiter. These weather patterns are driven by the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 kilometres per hour (580 m/s; 1,300 mph). Because of its great distance from the Sun, Neptune’s outer atmosphere is one of the coldest places in the Solar System, with temperatures at its cloud tops approaching 55 K (−218 °C). Temperatures at the planet’s center are approximately 5,400 K (5,100 °C). Neptune has a faint and fragmented ring system (labelled “arcs”), which was first detected during the 1960s and confirmed by Voyager 2. — Wikipedia
Neptune News -- ScienceDaily Planet Neptune News. Read astronomy articles on Neptune's oddball moon Triton. See images of Neptune and more.
'Cold Neptune' and two temperate super-Earths...
on January 14, 2020 at 2:09 pm
A 'cold Neptune' and two potentially habitable worlds are part of a cache of five newly discovered exoplanets and eight exoplanet candidates found orbiting nearby red dwarf stars. The two potentially habitable planets are among the nearest stars to our own Sun, making them prime targets for observations by next-generation space- and land-based telescopes.
Hidden giant planet revealed around tiny white...
on December 4, 2019 at 7:58 pm
The first evidence of a giant planet orbiting a dead white dwarf star has been found in the form of a disc of gas formed from its evaporating atmosphere.
NASA finds Neptune moons locked in 'dance of...
on November 14, 2019 at 7:00 pm
Even by the wild standards of the outer solar system, the strange orbits that carry Neptune's two innermost moons are unprecedented, according to newly published research.
Worldwide observations confirm nearby 'lensing'...
on November 1, 2019 at 1:38 pm
Researchers using telescopes around the world confirmed and characterized an exoplanet orbiting a nearby star through a rare phenomenon known as gravitational microlensing. The exoplanet has a mass similar to Neptune, but it orbits a star lighter (cooler) than the Sun at an orbital radius similar to Earth's orbital radius. The results of this research suggest that Neptune-sized planets could be common around this orbital region.
TESS discovers three new planets nearby,...
on July 29, 2019 at 3:13 pm
NASA's Transiting Exoplanet Survey Satellite, or TESS, has discovered three new worlds that are among the smallest, nearest exoplanets known to date. The planets orbit a star just 73 light years away and include a small, rocky super-Earth and two sub-Neptunes -- planets about half the size of our own icy giant.
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Possible discovery of a new super-Earth orbiting...
on January 16, 2020 at 12:27 pm
Astronomers have discovered another candidate exoplanet orbiting our neighbor Proxima Centauri. A paper announcing these results was just published in the journal Science Advances. If confirmed, it will be the second exoplanet discovered to be orbiting the star.
'Cold Neptune' and two temperate super-Earths...
on January 14, 2020 at 3:16 pm
A "cold Neptune" and two potentially habitable worlds are part of a cache of five newly discovered exoplanets and eight exoplanet candidates found orbiting nearby red dwarf stars, which are reported in The Astrophysical Journal Supplement Series by a team led by Carnegie's Fabo Feng and Paul Butler.
NEID exoplanet instrument sees first light
on January 9, 2020 at 8:28 am
The new NEID instrument, now installed at the 3.5-meter WIYN telescope at Kitt Peak National Observatory in Southern Arizona, USA, has made its first observations. The NSF-NASA funded instrument is designed to measure the motion of nearby stars with extreme precision—roughly three times better than the previous generation of state-of-the-art instruments—allowing us to detect, determine the mass of, and characterize exoplanets as small as Earth.
Planet WASP-12b is on a death spiral, say...
on January 8, 2020 at 1:48 pm
Earth is doomed—but not for 5 billion years. Our planet will be roasted as our sun expands and becomes a red giant, but the exoplanet WASP-12b, located 600 light-years away in the constellation Auriga, has less than a thousandth of that time left: a comparatively paltry 3 million years.
TESS mission uncovers its first world with two...
on January 7, 2020 at 8:14 am
In 2019, when Wolf Cukier finished his junior year at Scarsdale High School in New York, he joined NASA's Goddard Space Flight Center in Greenbelt, Maryland, as a summer intern. His job was to examine variations in star brightness captured by NASA's Transiting Exoplanet Survey Satellite (TESS) and uploaded to the Planet Hunters TESS citizen science project.