 MESSENGER WAC | |
| Planet | Mercury |
|---|---|
| Coordinates | 71°05′N31°38′W / 71.09°N 31.63°W |
| Quadrangle | Borealis |
| Diameter | 48.25 km (29.98 mi) |
| Eponym | Maija Grotell |
Grotell is a crater on Mercury. It has a diameter of 48.25 kilometres (29.98 miles). Its name was adopted by the International Astronomical Union (IAU) on April 24, 2012. [1] Grotell is named for the Finnish-American ceramist Maija Grotell. [2]
Mercury is the first planet from the Sun and the smallest in the Solar System. In English, it is named after the Roman god Mercurius (Mercury), god of commerce and communication, and the messenger of the gods. Mercury is classified as a terrestrial planet, with roughly the same surface gravity as Mars. The surface of Mercury is heavily cratered, as a result of countless impact events that have accumulated over billions of years. Its largest crater, Caloris Planitia, has a diameter of 1,550 km (960 mi) and one-third the diameter of the planet. Similarly to the Earth's Moon, Mercury's surface displays an expansive rupes system generated from thrust faults and bright ray systems formed by impact event remnants.
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune.
A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine-and-a-half times that of Earth. It has only one-eighth the average density of Earth, but is over 95 times more massive.
Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which in astronomy is called 'ice' or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of 49 K out of all the Solar System's planets. It has a marked axial tilt of 82.23° with a retrograde rotation rate of 17 hours. This means that in an 84-Earth-year orbital period around the Sun, its poles get around 42 years of continuous sunlight, followed by 42 years of continuous darkness.
The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins. They were dubbed maria by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to the naked eye. The maria cover about 16% of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are much smaller, residing mostly in very large craters. The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus ('lake'), palus ('marsh'), and sinus ('bay'). The last three are smaller than maria, but have the same nature and characteristics.
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of celestial bodies such as planets and their moons, asteroids, comets, and meteorites. Although the geo- prefix typically indicates topics of or relating to Earth, planetary geology is named as such for historical and convenience reasons; due to the types of investigations involved, it is closely linked with Earth-based geology. These investigations are centered around the composition, structure, processes, and history of a celestial body.
Mesoplanets are planetary-mass objects with sizes smaller than Mercury but larger than Ceres. The term was coined by Isaac Asimov. Assuming size is defined in relation to equatorial radius, mesoplanets should be approximately 500 km to 2,500 km in radius.
Paul D. Spudis (1952–2018) was an American geologist and lunar scientist. His specialty was the study of volcanism and impact processes on the planets, including Mercury and Mars.
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which was regarded as a planet before the "dwarf" concept was adopted in 2006.
Srīpur is a Martian impact crater, approximately 22.99 kilometres (14.29 mi) in diameter. It is located at -31.1°S, 100.8°W, southeast of the crater Dinorwic and northeast of the crater Tugaske. It is named for Sripur, a town in Bangladesh, and its name was adopted by the International Astronomical Union in 1991.
Neptune is the eighth and farthest planet from the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, and slightly more massive than its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. Being composed primarily of gases and liquids, it has no well-defined solid surface. The planet orbits the Sun once every 164.8 years at an orbital distance of 30.1 astronomical units. It is named after the Roman god of the sea and has the astronomical symbol , representing Neptune's trident.
Maija (Majlis) Grotell was an influential Finnish-American ceramic artist and educator. She is often described as the "Mother of American Ceramics."
LightSail is a project to demonstrate controlled solar sailing within low Earth orbit using a CubeSat. The project was developed by The Planetary Society, a global non-profit organization devoted to space exploration. It consists of two spacecraft — LightSail 1 and LightSail 2. LightSail 1 was an engineering demonstration mission designed to test its new sail deployment method in space, it did not perform solar sailing. LightSail 2 was a fully functional spacecraft intended to demonstrate true solar sailing and incorporated the lessons learned from LightSail 1. LightSail is a follow-on project to Cosmos 1 — a solar-sail spacecraft designed by The Planetary Society in the early 2000s, which was destroyed during a launch failure in 2005.
Leopardi is a crater on Mercury. Its name was adopted by the International Astronomical Union in 1976. Leopardi is named for the Italian writer Giacomo Leopardi, who lived from 1798 to 1837.
Larrocha is an impact crater on Mercury. It has a diameter of 196 km (122 mi), and it is one of 110 peak ring basins on Mercury. It is located in the Victoria quadrangle at 43.29°N 69.83°W.
 | This article about the planet Mercury is a stub. You can help Wikipedia by expanding it. |
