日批在线视频_内射毛片内射国产夫妻_亚洲三级小视频_在线观看亚洲大片短视频_女性向h片资源在线观看_亚洲最大网

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: 国产成人精品综合久久久久99 | 亚洲国内自拍 | 999国产精品视频免费 | 福利一区二区视频 | 亚洲视频综合 | www久久久久久 | 日本一级片在线观看 | 国产精品不卡一区二区三区 | 中文字幕视频二区 | 国产伦精品一区二区三区四区视频 | 国产精品www| 中日韩在线观看 | 午夜影院h | 国产成人av一区二区三区 | 国产一级大片在线观看 | 欧美激情国产精品免费 | 亚洲久视频 | 亚洲a在线观看 | 国产精品亚洲欧美 | 日本亚洲网站 | 欧美片在线观看 | 男人的伸进里面免费网站 | 亚洲第一页在线 | 成人午夜大片 | 亚洲欧洲国产综合 | 国产视频在线一区 | aaa成人 | 日本精品视频一区二区三区 | www.xxxx日本| 三级视频在线播放 | 欧美无遮挡 | 亚洲成人影院在线观看 | 99热香蕉 | 亚洲欧美视频在线 | 黄色网页在线观看 | 成人在线免费看 | 色综合视频在线观看 | 最新永久地址 | 天堂色在线 | 亚洲欧美视频在线观看 | 丝袜美腿在线 |