171218期:开普勒-90行星系

开普勒-90行星系

解释:其它恒星也会拥有类似于我们太阳系的行星系吗?会——比如开普勒-90行星系。最近,美国航空航天局(NASA)的开普勒太空望远镜在绕行恒星开普勒-90时发现了该星系的第八颗行星,这意味着开普勒-90星系拥有着与太阳系相同数量的已知行星。开普勒-90星系与太阳系的其它相似点包括:该星系的G型恒星与太阳相差无几,数颗岩态行星则与地球大小相当,数颗巨行星更是与木星、土星大小相当。而两者的差异在于,开普勒-90星系中所有已知行星与恒星的距离都小于地球与太阳的距离,因此这些温度过高的行星上可能无生命存在。不过,继续长期观察就可能发现该星系内距离恒星较远、温度偏低的行星。开普勒-90恒星远在2500光年之外,借助中等口径望远镜,我们可以在天龙座方向看到这颗14星等的恒星。今后的十年中,凌星系外行星巡天望远镜(TESS)、詹姆斯·韦伯太空望远镜(JWST)、宽视场红外巡天望远镜(WFIRST)和柏拉图太空望远镜(PLATO)会陆续上天执行寻找太阳系外行星的任务。

:银河说翻译组 飞果

The Kepler-90 Planetary System
Illustration Credit: NASA Ames, Wendy Stenzel

Explanation: Do other stars have planetary systems like our own? Yes — one such system is Kepler-90. Cataloged by the orbiting Kepler satellite, an eighth planet has now been discovered giving Kepler-90 the same number of known planets as our Solar System. Similarities between Kepler-90 and our system include a G-type star comparable to our Sun, rocky planets comparable to our Earth, and large planets comparable in size to Jupiter and Saturn. Differences include that all of the known Kepler-90 planets orbit relatively close in — closer than Earth’s orbit around the Sun — making them possibly too hot to harbor life. However, observations over longer time periods may discover cooler planets further out. Kepler-90 lies about 2,500 light years away, and at magnitude 14 is visible with a medium-sized telescope toward the constellation of the Dragon (Draco). Exoplanet-finding missions planned for launch in the next decade include TESS, JWST, WFIRST, and PLATO.

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