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.
TESS finds its first Earth-sized planet
on April 15, 2019 at 4:23 pm
A nearby system hosts the first Earth-sized planet discovered by NASA's Transiting Exoplanets Survey Satellite, as well as a warm sub-Neptune-sized world. This milestone sets the path for finding smaller planets around even smaller stars, and those planets may potentially be habitable. […]
Hubble captures birth of giant storm on Neptune
on March 25, 2019 at 4:03 pm
Images taken by the Hubble Space Telescope document the formation of a Great Dark Spot on Neptune for the first time, report researchers in a new study. […]
Icy giant planets in the laboratory
on March 25, 2019 at 3:02 pm
Giant planets like Neptune may contain much less free hydrogen than previously assumed. Researchers drove shock waves through two different types of plastic to reach the same temperatures and pressures present inside such planets, and observed the behavior using ultra-strong X-ray laser pulses. Unexpectedly, one of these plastics kept its crystalline structure even at the most extreme pressures. Since the icy giant interiors are made up of the same components as the plastic, planetary models […]
ALMA observes the formation sites of...
on March 13, 2019 at 3:47 pm
Researchers have spotted the formation sites of planets around a young star resembling our sun. Two rings of dust around the star, at distances comparable to the asteroid belt and the orbit of Neptune in our solar system, suggest that we are witnessing the formation of a planetary system similar to our own. […]
Tiny Neptune moon spotted by Hubble may have...
on February 21, 2019 at 2:50 pm
After several years of analysis, a team of planetary scientists using NASA's Hubble Space Telescope has at last come up with an explanation for a mysterious moon around Neptune that they discovered with Hubble in 2013. […]
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Next-generation NASA instrument advanced to study...
on April 25, 2019 at 4:59 pm
Much has changed technologically since NASA's Galileo mission dropped a probe into Jupiter's atmosphere to investigate, among other things, the heat engine driving the gas giant's atmospheric circulation. […]
Five planets revealed after 20 years of...
on April 18, 2019 at 12:04 pm
Over 4000 exoplanets have been discovered since the first one in 1995, but the vast majority of them orbit their stars with relatively short periods of revolution. Indeed, to confirm the presence of a planet, it is necessary to wait until it has made one or more revolutions around its star. This can take from a few days for the closest to the star to decades for the furthest away: Jupiter for example takes 11 years to go around the sun. Only a telescope dedicated to the search for exoplanets […]
NASA wants to send a low-cost mission to explore...
on April 17, 2019 at 12:26 pm
In the coming years, NASA has some bold plans to build on the success of the New Horizons mission. Not only did this spacecraft make history by conducting the first-ever flyby of Pluto in 2015, it has since followed up on that by making the first encounter in history with a Kuiper Belt object (KBO) – 2014 MU69 (aka Ultima Thule). […]
Astronomers discover third planet in the...
on April 16, 2019 at 1:30 pm
Astronomers have discovered a third planet in the Kepler-47 system, securing the system's title as the most interesting of the binary-star worlds. Using data from NASA's Kepler space telescope, a team of researchers, led by astronomers at San Diego State University, detected the new Neptune-to-Saturn-size planet orbiting between two previously known planets.&nbs […]
TESS finds its first Earth-sized planet
on April 15, 2019 at 4:31 pm
A nearby system hosts the first Earth-sized planet discovered by NASA's Transiting Exoplanets Survey Satellite, as well as a warm sub-Neptune-sized world, according to a new paper from a team of astronomers that includes Carnegie's Johanna Teske, Paul Butler, Steve Shectman, Jeff Crane, and Sharon Wang. […]