The Solar System Missions

Astronomers discover 'new planet'

Astronomers have detected what could be the Solar System's 10th planet.

It was first seen by astronomers using California's Palomar Observatory, and has been given the name "Sedna" after the Inuit goddess of the ocean. Observations show it measures about 1,180-2,360km (730-1,470 miles) across, making it similar in size to Pluto.

Astronomers now say they have evidence that Sedna has its own moon, although this needs to be confirmed, and is also very red in colour. There is likely to be some debate about whether it qualifies as a true planet, but some scientists are already saying it re-defines our Solar System.

BBC News – March 15, 2004

Astronomers discover 'new planet' - Sedna March 15, 2004

What’s New??

NEW YORK (AP) -- One of the nation's leading science museums has quietly shaken up the universe by suggesting that Pluto is not necessarily a planet at all but just a lump of ice. The startling suggestion comes from scientists at the Rose Center for Earth and Space, which opened last year at the American Museum of Natural History in New York.

Comparative Planetology – Dwarf Planets Pre June 2008

NameName CeresCeres PlutoPluto ErisEris

Clasification Dwarf Planet Dwarf Planet Dwarf Planet

Diameter (km)Diameter (km) 975 x 909975 x 909 23062306 24002400

Mass compared to earthMass compared to earth .00016.00016 .0022.0022 .0027.0027

Radius compared to earthRadius compared to earth .0738.0738 .180.180 .19.19

Date of DiscoveryDate of Discovery 01/01/180101/01/1801 02/18/193002/18/1930 01/05/200501/05/2005

Comparative Planetology – Plutoids and Dwarf Planets Post 2008

NameName CeresCeres PlutoPluto ErisEris MakemakeMakemake HaumeaHaumea

Clasification Dwarf Planet

Plutoid Accepted as Plutoid*

Accepted as Plutoid*

Accepted as Plutoid*

Diameter (km)Diameter (km) 975 x 909975 x 909 23062306 24002400 15001500 11501150

Mass Mass compared to compared to earthearth

.00016.00016 .0022.0022 .0027.0027 .0007.0007 .00074.00074

Radius Radius compared to compared to earthearth

.0738.0738 .180.180 .19.19 .23.23 .18.18

Date of Date of DiscoveryDiscovery

01/01/180101/01/1801 02/18/193002/18/1930 01/05/200501/05/2005 03/31/0503/31/05 12/28/0412/28/04

* Unclear if is in hydrostatic equilibrium

Comparative Planetology – Plutoids and Dwarf Planets Post 2008

NameName CeresCeres PlutoPluto ErisEris MakemakeMakemake HaumeaHaumea

Clasification Dwarf Planet

Plutoid Accepted as Plutoid

Accepted as Plutoid

Accepted as Plutoid

Diameter (km)Diameter (km) 975 x 909975 x 909 23062306 24002400 15001500 11501150

Mass Mass compared to compared to earthearth

.00016.00016 .0022.0022 .0027.0027 .0007.0007 .00074.00074

Radius Radius compared to compared to earthearth

.0738.0738 .180.180 .19.19 .23.23 .18.18

Date of Date of DiscoveryDiscovery

01/01/180101/01/1801 02/18/193002/18/1930 01/05/200501/05/2005 03/31/0503/31/05 12/28/0412/28/04

Beyond a doubt, more to come (there are many candidates)…

Comparative Planetology – Plutiods and Dwarf Planets

Comparative Planetology – Plutoids and Dwarf Planets

Note: 2003 UB313 is now called Eris

Ceres

Goddess of Plants (Roman)

Discovered: 01/01/1801

Classification: Dwarf Planet

Remains classified as a Dwarf Planet, and is believed to be the only object of its kind

Ceres

The International Astronomical Union has reclassified Ceres, the first asteroid to be discovered (and the largest and most massive object in the asteroid belt between Mars and Jupiter), as a "dwarf planet". Ceres was discovered on January 1, 1801 (technically the first day of the 19th Century) by Giuseppe Piazzi at Palermo, Sicily. He named it after Ceres, the Roman goddess of agriculture and grain.

Ceres was originally considered a planet, but when dozens of asteroids came to be discovered, it was reclassified in an asteroid. (I have an astronomy guide from the 1830s that lists 11 planets, the seven from Mercury to Uranus, plus Ceres, Pallas, Juno, and Vesta, the first four asteroids to be discovered.) I took this photo with a Canon Digital Rebel in late July when Ceres was in the constellation Piscis Austrinus; Ceres is between the marks at upper right. Comments

Ceres

Pluto

Pluto was discovered in 1930. Pluto's satellite Charon was discovered in 1978. Pluto is a low-density planet made up of 97% nitrogen. The combined mass of Pluto and Charon is 450 times less than Earthís mass. It rotates once every 6.39 Earth days and it revolves around the sun for 247.7 Earthís years.

As of 2011 – Pluto is now known to have 4 objects in orbit around it. The moons are Charon, Nix, Hydra and P4 (newest, still to be named as of 07/21/11

Discovered: 02/18/1930

Pluto

Ruler of the DeadPluto is known as the ruler of the dead and lives in the underworld and his name Pluto meant the giver of wealth since many precious gems and metals were found were he lived. His Greek name is Hades, which means the unseen. He owns a giant three-headed dog that guards the gates of the underworld. There is a myth of how Hades got his wife. When Hades got bored of the underworld, he wanted a wife. So he went up to earth to kidnap Persephone, the daughter of Demeter. When Demeter found out that her daughter was kidnapped, she became furious and went up to Jupiter. After a while, Jupiter decided that six months, Persephone would spend time with her mother, and another six months she would become queen of the dead. Whenever Persephone went down to the underworld, Demeter would be said and her tears would be the falling leaves of autumn. She would be so sad that all the crops would stop growing and everything would turn cold. When she saw Persephone, she would happy again and everything would come back to life, this is the mythological theory of the seasons. Pluto has a helmet of darkness that made him invisible during battle. In astrology, Pluto rules your private life.

Pluto

Pluto Facts Sheet:

Classification: Plutoid

Mass of planet (Earth=1) = 0.002Mean density (grams/centimeter³ ) = 2.03

Interior: Ice??

Surface:

Water:

Atmosphere: mostly nitrogen gas, just like that of the Earth and Saturn's moon Titan, with the addition of carbon monoxide (CO - what comes out of your car) and methane (CH4).

Moons: 4

Pluto

This is the clearest view of Pluto and its satellite Charon seen by the Hubble Space Telescope and taken by the European Space Agency's Faint Object Camera on February 21, 1994.

Pluto

Puto and its moons. HST in 2011.

Eris (Formerly 2003 UB313)

Goddess of Strife and Discord

First observed: 2003

Classification: Plutoid

Formal identification: 01/05/2005

About 10 Billion kilometers from the sun (96.7 AU)

Aphelion: 97.56 AU

Perihelion: 37.77 AU

The name Eris was chosen because of the strife and discord in the astronomical community over the official designation of Eris and,

maybe more popularly, the designation of Pluto as a planet.

Eris

A view of the solar system from the north down. The four circles show the orbits of Jupiter, Saturn, Uranus, and Neptune. The yellow dot in the center is the sun. The earth, if it were shown, would be inside the yellow dot representing the sun. The orbits of the two outermost planets, along with their current positions, are also shown. If you are worried because the sun appears to not be the focus of the orbital ellipse you are very observant! But it is just a projection effect.

Sedna

Spirit of the Sea

Sedna is the spirit of the sea according to the peoples of northern Canada and Greenland, named Inuit. Sedna resides at the bottom of the sea and has power over all animals. Her control of the sea, which the Inuit people depend on for their survival, gives Sedna an enormous power. Inuit people believe that success or failure in hunting depend on her unpredictable mood.

Sedna

Discovered: 11/14/2003

Classification: ???

About 10 Billion kilometers from the sun

Aphelion: 975.56 AU

Perihelion: 76.156 AU

It is not presently known if Sedna is in Hydrostatic equilibrium (condition 3 of the IAU planetary

definition), so its classification is currently not finalized.

Sedna

The discovery of Sedna resurrected the question of which astronomical objects should be considered planets and which should not. On March 15, 2004, articles in the popular press reported that "the tenth planet has been discovered". This question was answered under the new International Astronomical Union definition of a planet, adopted on August 24, 2006. It is unknown whether or not Sedna is in hydrostatic equilibrium. If, as currently suspected,[16] it is, then it would qualify as a dwarf planet. Sedna has a Stern–Levison parameter estimated at between 8 × 10-5 and 6 × 10-3 times that of Pluto,[17] and therefore cannot be considered to have cleared the neighbourhood of its orbit, even though no other objects have yet been discovered in its vicinity.

Image above: These three panels show the first detection of the faint distant object dubbed “Sedna.” Imaged on Nov 14 from 6:32 to 9:38 UT, Sedna was identified by te slight shift in position notes in these three pictures taken at different times. Image courtesy: NASA/Caltach.

Astronomers have announced the discovery of a large new planetoid named Sedna. Mike Brown of the California Institute of Technology, Chad Trujillo of the Gemini Observatory in Hawaii, and David Rabinowitz of Yale University in Connecticut discovered Sedna in November 2003. The astronomers cannot be certain of the exact size of the new planetoid, but they believe it is the largest object discovered in our Solar System since the discovery of Pluto in 1930. Sedna is also the furthest object from the Sun that has been found within our Solar System.Sedna is probably a huge ball of ice somewhere between 1,280 and 1,760 km (800 and 1,100 miles) in diameter. Sedna is remarkably reddish in color. Astronomers think that exposure to radiation over extremely long times may have altered the chemistry of some of the compounds within the ice, turning them red.Sedna orbits on the fringe of the known Solar System. It is currently at a distance of about 90 Astronomical Units (AU) from the Sun, more than twice as far away as Pluto. Its orbit is highly elliptical, and carries it around the Sun once every 10,500 years. It will reach perihelion (closest approach to the Sun) in 72 years at a distance of 76 AU, then slowly move away towards its extreme aphelion distance of 900 AU. Numerous similar icy planetoids, known as a group as Kuiper Belt Objects (KBO) or Trans-Neptunian Objects (TNO), have been found in the last decade. However, the TNOs seem to orbit within about 50 AU from the Sun, thus Sedna appears not to belong to that group. An area much further from the Sun, called the Oort Cloud, is thought to exist and be the source of many long period comets. Sedna does not seem to orbit quite far enough out to be part of the Oort Cloud, however, and scientists are trying to figure out how this new planetoid fits in to their big picture views of our Solar System.

Sedna

Comparative Planetology – Plutoids and Dwarf Planets

The study of objects in the solar system that are not classified by the IAU as

planets is still evolving and will continue to evolve into the future.