Philip S. Muirhead, Julie N. EP ; Solar and Stellar Astrophysics astro-ph. SR Cite as: arXiv EP] or arXiv Please follow Astrobiology on Twitter. TAGS: extrasolar planet. Advertise on SpaceRef. All rights reserved. What is Astrobiology? EP Posted March 19, PM View Comments Evolutionary tracks for low-mass stars, brown dwarfs and planetary-mass objects, showing effective temperature Teff and spectral type versus age, color-coded according to initial mass adapted from Burrows et al.
Dwarf planets of the solar system
Pluto is of course the most well known dwarf planet because of its previous classification as the outermost planet of the solar system. Rather like Ceres before it, it has suffered because of the number of similar objects now discovered in the same region mean that it can no longer be thought of as one of the major planets. Pluto was discovered by Clyde W.
Tombaugh on the 18th February after a long search for "Planet X" which was thought to exist due to perturbations in the orbit of Neptune. The name Pluto, after the god of the underworld, was proposed by Venetia Burney, an eleven-year-old schoolgirl in Oxford, England, who was interested in classical mythology.
She suggested it in a conversation with her grandfather Falconer Madan who passed the name to astronomy professor Herbert Hall Turner, who cabled it to colleagues in the United States. It was then chosen after a vote against other candidate names.
Listen to Venetia here. Pluto was visited for the first time ever by the New Horizons spacecraft which reached its closest approach on July 14, Scientific observations of Pluto began 5 months before closest approach and continued for a month after the encounter. Haumea is one of the stranger dwarf planets in that it does not appear to be spherical. It has an extremely fast for a planet rotation of once every 4 hours and this has pulled it into a ellipsoidal shape - rather like a squashed rugby or American football ball, spinning on its side.
Strange - but apparently still in hydrostatic equilibrium. It orbits the sun once every years and inhabits a similar area of space in the Kuiper Belt as Pluto.
Its orbit is inclined by 28 degrees to the ecliptic meaning it spends most of its time a long way above or below the ecliptic plane. It is thought to be comprised of rock with a thin covering of crystalline ice which is as bright as snow. However the low temperature degrees C and high radiation should mean that the crystalline ice should have turned to a red coloured amorphous ice over the last 10 million years or so meaning that Haumea's surface is possible much newer than expected.
Haumea has two moons, Hi'iaka and Namaka. These icy bodies have diameters of about km and km and orbit Haumea every 49 and 18 days respectively. Again the fact that they have crystalline ice means their surfaces are possibly relatively new. However it seems that the Caltech team got the pleasure of naming it "Haumea" after the Hawain goddess of fertility and childbirth. Because the team discovered Haumea on the 28th December, the team nicknamed it "Santa" and later the two moons "Rudolph" and "Blitzen". However due to IAU guidelines that classical Kuiper belt objects be named after mythological beings associated with creation, the Hawain names were chosen with Hi'iaka and Namaka being Haumea's children for the official names.
Makemake's orbit is similar to Haumea in that it resides in the Kuiper Belt with a 29 degree inclination to the ecliptic and with a year period orbit. It has a diameter of around km and appears to be reddish in colour. Like Pluto it has methane and possibly large amounts of ethane and tholins at its surface, and is covered by a very thin atmosphere at degrees C. It's thought to be spherical with a rotation of once every 8 hours. Makemake was discovered in by the same Caltech team who discovered Hameua and Eris, all of which were announced at the same time.
Initially codenamed "Easter Bunny" since it was discovered near Easter, it was officially named "Makemake", the creator of humanity and god of fertility in the mythos of the Rapanui, the native people of Easter Island. This name was chosen in part to preserve the object's connection with Easter.
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Just like Haumea, there have been no robotic missions to Makemake and none are currently underway. Eris has an orbital period of years and was at its furthest from Sun in at 97 AU e.
Sizes of the Dwarf Planets
It will come to its closest point to the Sun at sometime around 38 AU. With an orbit at almost 45 degrees to the plane of the ecliptic it travels over 30 AU to the north and 50 AU to the south of the ecliptic. It is currently around 30 AU from the ecliptic plane on the southern side but getting closer. Apart from long-period comets and space probes, Eris and its moon are currently the most distant known objects in the Solar System.
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Eris appears grey in colour and shows traces of methane in its atmosphere - rather like Pluto. A moon "Dysnomia" orbits Eris every 15 days. Because of the problems with observing such a small object at such distances many details about Dysnomia are vague. The diameter is thought to be somewhere between and km.
Discovered by the same team as Haumea and Makemake in , it was initially nicknamed "Xena" after the warrior princess TV character - and also because it began with X as in the fabled "Planet X". It was eventually named after the Greek goddess Eris, a personification of strife and discord.
The moon, Dysnomia, was named after the Greek goddess of lawlessness who was Eris' daughter. Mike Brown the team leader says he picked it for similarity to his wife's name, Diane. To find out more about the planets of our solar system, see our Planets page. Flash animations copyright : Hayling Graphics.
Our 5 Dwarf Planets | Britannica
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Wee Worlds: Our 5 (Official) Dwarf Planets
Planets Today Gifts. Solar System Planets Pluto and its moons LIVE. Solar System Maps. Planetary Positions. Dwarf Planets of the Solar System This page provides a brief description of each of the dwarf planets of our solar system. Link Approximate true-color image of Ceres, using the F7 'red' , F2 'green' and F8 'blue' filters, projected onto a clear filter image. It has no moons.
Click for Live Display showing current positions of Pluto and its moons.