Space Station Info :: Nine Planet Solar System :: History of Pluto :: Discovery of Pluto Planet

New Discovery Planet Earth

Ongoing discoveries in the transneptunian region keep rejuvenation the debate. In 2002, 50000 Quaoar was discovered, with a 1280 km diameter, making it quite more than half the size of Pluto. Another recent discovery, 90482 Orcus, is perhaps even larger. In 2004 the discoverers of 90377 Sedna, an extremely distant object well beyond the other known transneptunian objects, placed an upper limit of 1800 km on its diameter, close to Pluto's 2320 km.

Trans-Neptunian object called 2003 UB313 was announced in July 29, 2005,, which on the basis of its magnitude and simple albedo considerations is implicit to be larger than Pluto. This caused its discoverers to call it as the "10th planet" of the solar system, although there is no accord so far on whether to call it a planet, and others consider the new discovery to be the strongest dispute however for demoting Pluto to the status of a minor planet. 2003 UB313 could be the largest object yet discovered in the solar system since Neptune in 1846. The last remaining distinctive feature of Pluto is now its large moon, Charon, and its atmosphere; these characteristics may not, however, be unique to Pluto: several other transneptunian objects (not including Sedna) are known to have satellites; and 2003 UB313's spectrum suggests that it has a similar surface composition to Pluto, as well as a moon discovered in September of 2005.

There is some chronological model for "demoting" a "planet" in the light of consequent discoveries. The first four asteroids (1 Ceres, 2 Pallas, 3 Juno and 4 Vesta) were considered to be planets for several decades. Still, in 1845, the first new asteroid in 38 years was discovered, just one year before Neptune, and soon every year brought more asteroid discoveries. It was soon accepted that Ceres and the others were just the most well-known members of a populous asteroid belt, and although asteroids are also known as "minor planets", they are no longer considered "planets". Some see in this a precedent for noting that Pluto is just the most important member of the Kuiper belt.

In contrast, it may very well regardless of of future astronomical discoveries; Pluto will stay grandfathered as a planet in much the same way that Europe is considered a separate continent for past reasons although geographically it makes more sense, from first ideology, to consider both Europe and Asia to encompass the single continent of Eurasia.

See about:

vHistory of Pluto
vPluto Discovery And Naming
vPluto Physical Characteristics
vPluto's Moon
vExploration Of Pluto
vThe Pluto Debate
vPluto New Discoveries