Credit: International Astronomical Union
Explanation:
How many planets are in the Solar System?
This popular question now has a new formal answer according the
International Astronomical Union (IAU): eight.
Last week, the IAU voted on a
new definition for planet and
Pluto did not make the cut.
Rather, Pluto was re-classified as a
dwarf planet and is considered
as a prototype for a new category of
trans-Neptunian objects.
The eight planets now recognized by the IAU are:
Mercury,
Venus,
Earth,
Mars,
Jupiter,
Saturn,
Uranus, and
Neptune.
Solar System objects now classified as dwarf planets are:
Ceres,
Pluto, and the currently unnamed
2003 UB313.
Planets, by the new IAU definition, must be in orbit around the sun, be nearly spherical,
and must have cleared the neighborhood around their orbits.
The demotion of
Pluto to dwarf planet
status is a source of continuing
dissent and controversy in the astronomical community.
1999 2000 2001 2002 2003 2004 2005 2006 2007 |
Январь Февраль Март Апрель Май Июнь Июль Август Сентябрь Октябрь Ноябрь Декабрь |
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
|
Публикации с ключевыми словами:
планеты - планетная система - солнечная система
Публикации со словами: планеты - планетная система - солнечная система | |
См. также:
Все публикации на ту же тему >> | |
Мнение читателя [1]
