男女羞羞视频在线观看,国产精品黄色免费,麻豆91在线视频,美女被羞羞免费软件下载,国产的一级片,亚洲熟色妇,天天操夜夜摸,一区二区三区在线电影

NASA discovers 1st Earth-size planets beyond solar system

Updated: 2011-12-21 09:57

(Xinhua)

  Comments() Print Mail Large Medium  Small 分享按鈕 0

NASA discovers 1st Earth-size planets beyond solar system

An artist's rendering shows a planet called Kepler-20e in this handout released December 20, 2011. NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system, a milestone in the search for planets like the earth, the space agency said on Tuesday. [Photo/Agencies]

WASHINGTON?- NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system, the US space agency announce Tuesday.

The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface, but they are the smallest exoplanets ever confirmed around a star like our sun, according to NASA.

The discovery marks the next important milestone in the ultimate search for planets like Earth. The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth. Kepler-20f is slightly larger than Earth, measuring 1.03 times its radius. Both planets reside in a five-planet system called Kepler-20, approximately 1, 000 light-years away in the constellation Lyra.

Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days. These short orbital periods mean very hot, inhospitable worlds. Kepler-20f, at 427 Celsius degrees(800 degrees Fahrenheit), is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 760 Celsius degrees(1,400 degrees Fahrenheit), would melt glass.

"The primary goal of the Kepler mission is to find Earth-sized planets in the habitable zone," said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, lead author of a new study published in the journal Nature. "This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them."

The Kepler-20 system includes three other planets that are larger than Earth but smaller than Neptune. Kepler-20b, the closest planet, Kepler-20c, the third planet, and Kepler-20d, the fifth planet, orbit their star every 3.7, 10.9 and 77.6 days. All five planets have orbits lying roughly within Mercury's orbit in our solar system. The host star belongs to the same G-type class as our sun, although it is slightly smaller and cooler.

NASA discovers 1st Earth-size planets beyond solar system

This handout image by NASA on Dec. 20, 2011 shows an artist's conception illustrating Kepler-20f. NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface, but they are the smallest exoplanets ever confirmed around a star like our sun. Kepler-20f is the closest object to the Earth in terms of size ever discovered. With an orbital period of 20 days and a surface temperature of 800 degrees Fahrenheit, it is too hot to host life, as we know it.[Photo/Xinhua]

 

NASA discovers 1st Earth-size planets beyond solar system

This handout image by NASA on Dec. 20, 2011 shows a chart comparing the first Earth-size planets found around a sun-like star to planets in our own solar system, Earth and Venus. [Photo/Xinhua]

主站蜘蛛池模板: 栖霞市| 新龙县| 怀柔区| 桃园县| 腾冲县| 辽阳市| 海原县| 宜兰市| 西充县| 当涂县| 永嘉县| 中宁县| 贵溪市| 瑞丽市| 肥东县| 普兰县| 固原市| 盖州市| 湖州市| 舒城县| 襄垣县| 阿瓦提县| 梅河口市| 乌海市| 祥云县| 郴州市| 辽源市| 筠连县| 五台县| 日照市| 贡觉县| 布尔津县| 定兴县| 桂东县| 章丘市| 秦皇岛市| 友谊县| 锡林郭勒盟| 汉寿县| 泸定县| 固始县| 平阳县| 双牌县| 安多县| SHOW| 宣化县| 林甸县| 河间市| 磴口县| 集贤县| 金溪县| 福清市| 辽阳市| 江阴市| 叶城县| 桃江县| 朔州市| 东兰县| 海林市| 北流市| 鄂伦春自治旗| 灵石县| 汨罗市| 保德县| 江城| 甘肃省| 白河县| 阳谷县| 南江县| 浦东新区| 纳雍县| 马公市| 紫阳县| 阜阳市| 正宁县| 普陀区| 英德市| 大同县| 中方县| 垦利县| 枞阳县| 远安县|