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.
Odd bodies, rapid spins keep cosmic rings close
on November 19, 2018 at 8:59 pm
Forget those shepherding moons. Gravity and the odd shapes of asteroid Chariklo and dwarf planet Haumea -- small objects deep in our solar system -- can be credited for forming and maintaining their own rings, according new research. […]
Evidence of early planetary shake-up
on September 10, 2018 at 3:12 pm
Scientists have studied an unusual pair of asteroids and discovered that their existence points to an early planetary rearrangement in our solar system. […]
New exoplanet found very close to its star
on September 5, 2018 at 8:19 pm
Using data from NASA's Kepler Space Telescope, an international team has discovered a new exoplanet twice the size of Earth. It orbits its star every six days and is thus very close to it, about 10 times closer than Mercury is to the Sun. […]
Collective gravity, not Planet Nine, may explain...
on June 4, 2018 at 5:17 pm
Bumper car-like interactions at the edges of our solar system -- and not a mysterious ninth planet -- may explain the dynamics of strange bodies called 'detached objects,' according to a new study. […]
From car engines to exoplanets
on April 4, 2018 at 3:47 pm
Chemical models developed to help limit the emission of pollutants by car engines are being used to study the atmospheres of hot exoplanets orbiting close to their stars. […]
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NASA's Voyager 2 probe enters interstellar space
on December 10, 2018 at 3:50 pm
For the second time in history, a human-made object has reached the space between the stars. NASA's Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun. […]
Unknown treasure trove of planets found hiding in...
on December 6, 2018 at 7:33 pm
"Super-Earths" and Neptune-sized planets could be forming around young stars in much greater numbers than scientists thought, new research by an international team of astronomers suggests. […]
Helium exoplanet inflated like a balloon,...
on December 6, 2018 at 7:00 pm
Astronomers have discovered a distant planet with an abundance of helium in its atmosphere, which has swollen to resemble an inflated balloon. […]
An exoplanet loses its atmosphere in the form of...
on December 6, 2018 at 7:00 pm
A new study led by scientists from the Instituto de Astrofísica de Canarias (IAC) reveals that the giant exoplanet WASP-69b carries a comet-like tail made up of helium particles escaping from its gravitational field and propelled by the ultraviolet radiation of its star. The results of this work are published today in the journal Science. […]
A new way to create Saturn's radiation belts
on November 29, 2018 at 2:16 pm
A team of international scientists from BAS, University of Iowa and GFZ German Research Centre for Geosciences has discovered a new method to explain how radiation belts are formed around the planet Saturn. […]