Dwarf Planets

A celestial body resembling a small planet but lacking certain technical criteria that are required for it to be classed as such.

Ceres

Ceres is the smallest dwarf planet, the closest dwarf planet to the Sun, and the largest object in the main asteroid belt that lies between the orbits of Mars and Jupiter. With a diameter of 940 km, Ceres is both the largest of the asteroids and the only dwarf planet inside Neptune's orbit.

Radius: 473 km

Discovered: 1 January 1801

Orbital period: 1,682 days

Discoverer: Giuseppe Piazzi

Proper orbital period: 4.60397 yr; (1681.601 d)

Temperature: The surface is relatively warm for an asteroid, the average surface temperature is about 235 degrees Kelvin or minus 36 degrees Fahrenheit or minus 38 degrees Celsius.

Diameter: 946 km

Atmosphere: Ceres has a very thin atmosphere, and there is evidence it contains water vapor. The vapor may be produced by ice volcanoes or by ice near the surface sublimating (transforming from solid to gas).

Gravity: 0.27 m/s²

Name origin: Piazzi called his discovery Ceres after the Roman goddess of harvests and corn.

White Spot: The probe's observations have since revealed that the bright spots are salty deposits, composed primarily of sodium carbonate and ammonium chloride.

Age: 4.573 billion years

Zodiac: In astrology, Ceres represents the natural world, the rhythms of the seasons, womanhood and fertility, parenting and reproduction, fostering and adopting. Her themes are unconditional love, relationships between parents and children, and all the issues of devotion, attachment, separation, sacrifice, loss, and grief.

Pluto

Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It was the first and the largest Kuiper belt object to be discovered. After Pluto was discovered in 1930, it was declared to be the ninth planet from the Sun.

Orbital period: 248 years

Discovered: 18 February 1930

Radius: 1,188.3 km

Discoverer: Clyde Tombaugh

Moons: Charon, Nix, Hydra, Styx, Kerberos

Colors: Pluto's visual apparent magnitude averages 15.1, brightening to 13.65 at perihelion. In other words, the planet has a range of colors, including pale sections of off-white and light blue, to streaks of yellow and subtle orange, to large patches of deep red.

Mass: Although all of the planets beyond Mars are gas giants, Pluto is small and rocky. The tiny body has a mass of only 1.31 x 1022 kilograms, about two-tenths of a percent of Earth's. It has a volume of 1.5 billion cubic miles (6.4 billion cubic km).

Zodiac sign: In the birth chart, Pluto shows the area of life where you'll personally face the intense powers of creation and destruction. It's the doorway through which volatile compressed pockets of self, spirit and primal energy lies hidden, which are released either by our own efforts or by provocation from the outside world.

Weight: 12,500,000,000,000,000,000,000 kilograms

Pluto is the smallest of all of the planets in the Solar System. It weighs 12,500,000,000,000,000,000,000 kilograms. While this may seem large, it's only about 1/500th of the Earth's mass. Pluto is between 2200 and 2400 kilometers across.

Type of Planet: dwarf planet

Answer. The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet. Essentially Pluto meets all the criteria except one—it "has not cleared its neighboring region of other objects."

Diameter: 2,376.6 km

Total moons: The dwarf planet Pluto has five natural satellites. Charon, the largest of the five moons, is mutually tidally locked with Pluto, and is massive enough that Pluto–Charon is sometimes considered a double dwarf planet.

Distance from Sun: 39.5 astronomical units

On average, Pluto is a distance of 39.5 astronomical units, or AU, from the sun. That is almost 40 times farther from the sun than Earth is. Because of its elliptical orbit, Pluto is not the same distance from the sun all the time. Pluto's closest point to the sun is 29.7 AU.

Temperature: -375 to -400 degrees Fahrenheit

Surface. Pluto's surface is characterized by mountains, valleys, plains, and craters. The temperature on Pluto can be as cold as -375 to -400 degrees Fahrenheit (-226 to -240 degrees Celsius).

Name Origin: Pluto is the only world (so far) named by an 11-year-old girl. In 1930, Venetia Burney of Oxford, England, suggested to her grandfather that the new discovery be named for the Roman god of the underworld. He forwarded the name to the Lowell Observatory and it was selected.

Charon name origin(Moon of Pluto): The name Charon is a boy's name meaning "of keen gaze". The name of the ferrymen of dead souls to the Greek underworld and the name of Pluto's desolate moon, Charon makes an interesting, if somewhat macabre, choice for a baby.

Nix name origin(Moon of Pluto): The name Nix was approved by the International Astronomical Union (IAU) and was announced on 21 June 2006 along with the naming of Hydra in the IAU Circular 8723. Nix was named after Nyx, the Greek goddess of darkness and night and mother of Charon, the ferryman of Hades in Greek mythology.

Hydra name origin(Moon of Pluto): The name Nix was approved by the International Astronomical Union (IAU) and was announced on 21 June 2006 along with the naming of Hydra in the IAU Circular 8723. Nix was named after Nyx, the Greek goddess of darkness and night and mother of Charon, the ferryman of Hades in Greek mythology.

Styx name origin(Moon of Pluto): Moon No. 5 is Styx, named for the river that souls had to cross over to get to Hades, or the underworld, and the goddess who ruled over it.

Kerberos name origin(Moon of Pluto): It was initially called "P4", meaning the fourth Plutonian moon to be discovered. ... Cerberus is already the name of an asteroid, 1865 Cerberus, but the Greek form of the name, Kerberos, was acceptable to the IAU. On 2 July 2013, the IAU announced that it formally approved the names Kerberos for P4 and Styx for P5.

Haumea

Haumea (minor-planet designation 136108 Haumea) is a dwarf planet located beyond Neptune's orbit.[22] It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory in the United States and independently in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, though the latter claim has been contested. On September 17, 2008, it was named after Haumea, the Hawaiian goddess of childbirth, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. It is probably the third-largest known trans-Neptunian object, after Eris and Pluto.

Haumea's mass is about one-third that of Pluto, and 1/1400 that of Earth. Although its shape has not been directly observed, calculations from its light curve are consistent with it being a Jacobi ellipsoid (the shape it would be if it were a dwarf planet), with its major axis twice as long as its minor. In October 2017, astronomers announced the discovery of a ring system around Haumea, representing the first ring system discovered for a trans-Neptunian object. Haumea's gravity was until recently thought to be sufficient for it to have relaxed into hydrostatic equilibrium, though that is now unclear. Haumea's elongated shape together with its rapid rotation, rings, and high albedo (from a surface of crystalline water ice), are thought to be the consequences of a giant collision, which left Haumea the largest member of a collisional family that includes several large trans-Neptunian objects and Haumea's two known moons, Hiʻiaka and Namaka.

Orbital period: 284 years

Radius: 816 km

Discovered: 28 December 2004

Age: 4.503 billion years

Moons: Namaka, Hiʻiaka

Discoverers: Michael E. Brown, José Luis Ortiz Moreno

Composition

Unlike most objects in the Kuiper belt, Haumea is not an equal mixture of ice and rock but likely has a thin water ice crust covering a rocky interior. It is one of the densest Kuiper belt objects, with a density of 1.885 grams per cubic centimeter.

Mass: 4,006,000,000,000 billion kg (0.00066 x Earth)

Equatorial Diameter: 1,960 km – 1,518 km

Known Moons: 2

Notable Moons: Hi'iaka & Namaka

Orbit Distance: 6,452,000,000 km (43.13 AU)

Colors: Observations of Haumea, however, reveal a brightly gleaming surface. Scientists have concluded that, though most of Haumea's interior is rocky, it is covered by a thin icy shell. Haumea also appears to have a dark red spot on its surface that may contain more minerals and organic compounds than the ice around it.

Appearance: OverviewOriginally designated 2003 EL61 (and nicknamed Santa by one discovery team), Haumea resides in the Kuiper belt and is roughly the same size as Pluto. Haumea is one of the fastest rotating large objects in our solar system. Its fast spin distorts Haumea's shape, making this dwarf planet look like a football.

Distance from the Sun: 43 astronomical units

From an average distance of 4,010,000,000 miles (6,452,000,000 kilometers), Haumea is 43 astronomical units away from the Sun.

Hi'iaka name origin(Moon of Haumea): Hiʻiaka, or the youngest Hiiaka, was the patron goddess of Hawaiʻi, hula dancers, chant, sorcery and medicine. ... Her common and family name means "carried egg" - "hiʻi", to hold or carry in the arms (as a child), and "aka", meaning embryo - referring to the story of how she was brought to Hawaiʻi by her sister Pele.

Namaka name origin(Moon of Haumea): Namaka is a water spirit in Hawaiian mythology.

Temperature: -241°C

Diameter: 1,632 km

Rings: Haumea is the first known Kuiper Belt Object to have rings. Scientists announced the discovery in 2017 after watching the dwarf planet pass in front of a star.

Atmosphere: If you were on Haumea and look up in the sky, you would probably see no sky, no atmosphere because its gravity can't hold on to an atmosphere. Haumea's biggest moon Hi'iaka is eight times more close to Haumea than our moon is to Earth.

Gravity: 0.401 m/s²

Name origin: Haumea is named after the Hawaiian goddess of childbirth. The two moons in orbit around Haumea were named after two of the children of Haumea. Hi'iaka is the larger moon, while the smaller moon was named Namaka. It is believed that these moons formed as a result of a collision between Haumea and some other body.

Makemake

Makemake is a likely dwarf planet and perhaps the second largest Kuiper belt object in the classical population, with a diameter approximately two-thirds that of Pluto. Makemake has one known satellite.

Orbital period: 306 years

Discovered: 31 March 2005

Radius: 715 km

Distance to Earth: 5.61 billion km

Moon: S/2015 (136472) 1

Discoverers: Michael E. Brown, Chad Trujillo, David L. Rabinowitz

Mass: 3,000,000,000,000 billion kg

Origin: The word Makemake is Polynesian in origin and is the name of the creator of humanity and the god of fertility in the mythology of the South Pacific island of Rapa Nui or the Easter Island.

Zodiac sign: Makemake has an eliptical orbit of about 309 years around the Sun, and unlike Eris and Pluto, Makemake appears to have no moon(s). The teaching in western astrology is that when a new planet is discovered and named, the archetype of that planet becomes available for everyone.

Density: 3.2 g/cm³

With an estimated mean density of 1.4–3.2 g/cm³, Makemake is believed to be differentiated between an icy surface and a rocky core.

Moon: S/2015 (136472) 1

Makemake has one provisional moon, S/2015 (136472) 1 and nicknamed MK 2. It is more than 1,300 times fainter than Makemake. MK 2 was seen approximately 13,000 miles from the dwarf planet, and its radius is estimated to be about 50 miles (80 kilometers).

Distance From the Sun: 45.8 astronomical units

From an average distance of 4,253,000,000 miles (6,847,000,000 kilometers), Makemake is 45.8 astronomical units away from the sun. One astronomical unit (abbreviated as AU), is the distance from the sun to Earth.

Eris

Eris is the most massive and second-largest known dwarf planet in the Solar System. Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its discovery was verified later that year. In September 2006 it was named after the Greco-Roman goddess of strife and discord.

Orbital period: 558 years

Radius: 1,163 km

Discovered: 5 January 2005

Named after: Ἔρις Eris

Moon: Dysnomia

Discoverers: Michael E. Brown, Chad Trujillo, David L. Rabinowitz

Distance from sun: about 68 astronomical units

Eris, like Pluto, is a little smaller than Earth's Moon. If the Earth were the size of a nickel, Eris would be about as big as a popcorn kernel. From an average distance of 6,289,000,000 miles (10,125,000,000 kilometers), Eris is about 68 astronomical units away from the Sun.

Mass: Observations of Dysnomia's orbit permitted scientists to determine the mass of Eris, which in June 2007 they calculated to be (1.66±0.02)×1022 kg, 27%±2% greater than Pluto's.

Temperature: It takes 557 Earth years for Eris to make one orbit around the Sun. It has a highly eccentric orbit around the Sun, which causes its surface temperature to vary from -217 degrees Celsius to -243 degrees Celsius.

Length of day: A day on Eris takes 25.9 hours. Eris has one moon, Dysnomia. Pluto, discovered in 1930, orbits the sun at an average of 39.5 times the Earth's distance. Its diameter is 1,430 miles (2,302 km).

Name origin of Dysnomia The moon of Eris: Keck Observatory, and carried the provisional designation of S/2005 (2003 UB313) 1 until officially named Dysnomia (from the Ancient Greek word Δυσνομία meaning anarchy/lawlessness) after the daughter of the Greek goddess Eris.