Xena

more...

Home
Advertising
Badges/ Patches
Bottles/ Pots
Breweriana
Cigarette/ Tea/ Gum Cards
Clocks
Decorative Ornaments/ Plates
Disneyana
Ethnographic
Fantasy/ Myth/ Magic
Angel
Buffy the Vampire Slayer
Discworld
Harry Potter
Lord of the Rings/ Tolkien
Magic
Mythical Creatures
Other Fantasy/ Myth/ Magic
Xena
Flags
Household
Jukeboxes
Keyrings
Kitchenalia
Knives/ Swords
Masonic
Memorabilia
Metalware
Militaria
Moneyboxes/ Piggy Banks
Paper & Ephemera
Pens & Writing Equipment
Phone Cards
Photographic Images
Radio/ Television/ Telephony
Religion/ Spirituality
Rocks/ Fossils/ Minerals
Royalty
Science Fiction
Scientific
Sewing/ Fabric/ Textiles
Theatre/ Opera/ Ballet
Tobacciana/ Smoking
Tools & Hardware
Trading Cards/ CCG

Eris (IPA pronunciation /ˈɛɹɪs/) or /ˈiɹɪs/), also designated (136199) Eris or 136199 Eris (See Minor planet names), is the largest known dwarf planet in the solar system. It is a trans-Neptunian object (TNO), orbiting the Sun in a region of space known as the scattered disc, just beyond the Kuiper belt, and accompanied by at least one moon, Dysnomia. Mike Brown, who led the Mount Palomar-based discovery team, announced in April 2006 that the Hubble Telescope has measured Eris's diameter to be 2400 km, slightly larger than that of Pluto.

Eris' size resulted in its discoverers and NASA labelling it the solar system's tenth planet. This, along with the prospect of other similarly sized objects being discovered in the future, stimulated the International Astronomical Union (IAU) to define the term "planet" more precisely. Under a new definition approved on August 24, 2006, Eris was designated a "dwarf planet" along with Pluto and Ceres. Brown has since stated his approval of the new "dwarf planet" label.

Discovery

Eris was discovered by the team of Mike Brown, Chad Trujillo, and David Rabinowitz on January 5, 2005, from images taken on October 21, 2003. The discovery was announced on July 29, 2005, the same day as two other large TNOs, (136108) 2003 EL₆₁ and (136472) 2005 FY₉. The search team has been systematically scanning for large outer solar system bodies for several years, and had previously been involved in the discovery of several other very large TNOs, including 50000 Quaoar, 90482 Orcus, and 90377 Sedna.

Routine observations were taken by the team on October 21, 2003, using the 48-inch (122 cm) Samuel Oschin reflecting telescope at Mount Palomar Observatory, California, but the object captured on the images was not discovered at that point due to its very slow motion across the sky: the team's automatic image-searching software excluded all objects moving at less than 1.5 arcseconds per hour to reduce the number of false positives returned. When Sedna was discovered, it was moving at 1.75 arcsec/h, and in light of that the team reanalyzed their old data with a lower limit on the angular motion, sorting through the previously excluded images by eye. In January 2005, the re-analysis revealed Eris' slow motion against the background stars.

Follow-up observations were then carried out to make a preliminary determination of its orbit, which allowed its distance and size to be estimated. The team had planned to delay announcing their discovery until further observations had been made which would have allowed more accurate determinations of the body's size and mass, but were forced to bring forward the announcement when the discovery of another object they had been tracking (2003 EL₆₁) was announced by another group in Spain.

Read more at Wikipedia.org