Neptune
Neptune is the eighth and farthest-known Solar planet from the Sun. It is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. The planet orbits the Sun once every 164. 8 years at an average distance of 30. 1AU. Neptune has a faint and fragmented ring system, which was discovered in 1984, then later confirmed by Voyager2.
About Neptune in brief
Neptune is the eighth and farthest-known Solar planet from the Sun. It is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. The planet orbits the Sun once every 164. 8 years at an average distance of 30. 1AU. 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. Its largest moon, Triton, was discovered shortly thereafter, though none of the planet’s remaining 13 known moons were located telescopically until the 20th century. Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989; Voyager 2 remains the only spacecraft to visit Neptune. 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 has a faint and fragmented ring system, which was discovered in 1984, then later confirmed by Voyager2. Like Jupiter and Saturn, Neptune’s atmosphere is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen, though it contains a higher proportion of water, ammonia and methane. Traces of methane in the outermost regions in part account for the planet’s blue appearance. Neptune’s outer atmosphere is one of the coldest places in the solar System, with temperatures at its cloud tops approaching 55 K. Temperatures at the planet its centre are approximately 5,400 K Neptune’s southern hemisphere had a Great Dark Spot comparable to the Great Red Spot on Jupiter, with recorded wind speeds as high as 2,100 kmh.
It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune’s trident. At his first observation in December 1612, Neptune was almost stationary in the sky because it had just turned retrograde that day. This apparent backward motion is created when Earth’s orbit takes it past an outer planet. On both occasions, Galileo seems to have mistaken Neptune for a fixed star when it appeared close—in conjunction—to Jupiter in the night sky. Hence, he is not credited with Neptune’s discovery. In 2009, a study suggested that Galileo was at least aware that the star he had observed had moved relative to the fixed stars. In 1821, Alexis Bouvard published astronomical tables of Neptune’s neighbour Uranus, leading to the hypothesise that an unknown body was pertbing the orbit through gravitational interaction. In June 1843, John Couch Adams began work on the orbit of Uranus using the data he had requested from Sir George Airy, who supplied it in February 1844–46 and produced several different estimates of a new planet. In July 1845–46, Urbain Le Verrier published his estimate of the longitude and longitude of Neptune, and in June 1846, the Royal Astronomer published his first estimate of its longitude.
You want to know more about Neptune?
This page is based on the article Neptune published in Wikipedia (as of Dec. 06, 2020) and was automatically summarized using artificial intelligence.
