www射-国产免费一级-欧美福利-亚洲成人福利-成人一区在线观看-亚州成人

WORLD> Europe
Stripped of planet status, Pluto saves face
(Agencies)
Updated: 2008-06-12 22:59

PARIS - Two years after Pluto was struck from the planetary A-list and downgraded to "dwarf-planet" status, the ninth rock from the Sun regained some dignity Thursday by lending its name to a new category of celestial bodies.


A handout from the International Astronomical Union shows the celestial bodies Pluto (left) and Eris. Two years after Pluto was stricken from the planetary A-list and downgraded to "dwarf-planet" status, the ninth rock from the Sun regained some dignity by lending its name to a new category of celestial bodies. [Agencies] 

In a revised taxonomy of the mainly lifeless objects circling the Sun, those fulfilling all the criteria of planets except one -- the ability to "clear the neighborhood" around their orbit -- will now be called "plutoids", the International Astronomical Union (IAU) announced.

If, that is, they are further from the Sun than Neptune, which became the outermost planet in our solar system after Pluto was stripped of its planetary stripes.

Neptune orbits the Sun once every 164.8 years at a distance of 4.5 billion kilometres (2.8 billion miles).

Besides Pluto, the second known and named plutoid is called Eris. Increasingly powerful tools for exploring the outer boundaries of the Solar System insure that others will be found, astronomers say.

After an impassioned debate -- and over the strenuous objections of many astronomers and star gazers -- the IAU declassified Pluto as a full-fledged planet in August 2006.

Along with Erin and a third wannabe planet, Ceres, nestled in the asteroid belt between Mars and Jupiter, Pluto was provisionally given the status of "dwarf-planet" pending today's decision on nomenclature.

Ceres, because it is closer to the Sun than Neptune, will remain a dwarf-planet.

All three categories -- planet, dwarf-planet and plutoid -- share two core characteristics, the 10,000-strong astronomical association decided.

They are celestial bodies that are in orbit around our Sun, and they have sufficient mass such that self-gravity can overcome what are called "rigid body forces" to assume a nearly spherical shape.

But only those orbiting masses that can also sweep other celestial bodies from the area around their orbits can be considered as genuine planets.

The change of definition left eight planets, counting outward from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Pluto is 2,274 kilometres (1,413 miles) in diameter and 5.9 billion kilometres (3.7 billion miles) from the Sun. It takes 247.7 Earth years to complete an orbit, and has one large moon and two small ones.

In Spanish and French, the new category of dwarf-planet will be called "plutoide".

The IAU has been responsible for naming planetary bodies and their satellites since the early 1900s.

主站蜘蛛池模板: 露脸 在线 国产 眼镜 | 精品区| 中文字幕视频免费在线观看 | 亚洲国产情侣一区二区三区 | 中文字幕日韩在线 | 日本特级淫片免费看 | 成人三级在线观看 | 一级伦理电线在2019 | 青青自拍 | 国内精品久久久久久久久久影视 | 日韩欧美在线观看视频一区二区 | 日本69色视频在线观看 | 另类亚洲孕妇分娩网址 | 99re8免费视频精品全部 | 特级av毛片免费观看 | 亚洲第一网色综合久久 | 国产成人综合一区精品 | 成人性视频在线三级 | 碰碰碰人人澡人人爱摸 | 国产精品亚洲片夜色在线 | 国产亚洲精品美女一区二区 | 国产精品三 | 国产一区影视 | 欧美日韩一区二区在线 | 91精品国产综合久久香蕉 | 久久免费在线观看 | 美女视频黄a | 欧美一级特黄乱妇高清视频 | 欧美高清一区二区三 | 女初高中福利视频在线观看 | 一区二区三区观看 | 亚洲成人影院在线观看 | 国产三级久久 | 91成年人免费视频 | 222aaa天堂 | 久久亚洲精品中文字幕第一区 | 日本丶国产丶欧美色综合 | 美女综合网 | 看一级毛片一区二区三区免费 | a在线观看欧美在线观看 | 私人玩物福利 |