开勒普-90的行星系统

2020 April 28

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 Kepler satellite that operated from Earth orbit between 2009 and 2018, eight planets were 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). The exoplanet-finding mission TESS was launched in 2018, while missions with exoplanet finding capability planned for launch in the next decade include NASA’s JWST and WFIRST.

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开勒普-90的行星系统
图标提供：NASA Ames, Wendy Stenzel

说明：其它恒星有类似太阳系的行星系统吗？有，范例之一是开勒普-90的行星系统。2009年到2018年之间在地球轨道上运转的开勒普卫星，在开勒普-90找到8颗行星，因此它具有和太阳系相同的行星数。在开勒普-90和太阳系的诸多相似点中，包括二者的母星都是G型星，成员中有像地球的石质行星，以及大小和木星及土星相当的巨行星。主要相异点在于开勒普-90的行星离母星的距离，都比地球和太阳的间距要小，所以可能太热生命难以存活。不过，更长期的观测或许能在这个系统的更外围，找到较低温的行星。开勒普-90离我们约2，500光年，中型的望远镜可在天龙座方向看到这颗14星等的恒星。目前在进行系外行星搜寻的卫星为2018年发射的TESS（凌星系外行星巡天卫星），而在10年内会发射的卫星任务有美国航天总署的JWST（詹姆斯·韦伯太空望远镜）和WFIRST（大视场红外巡天望远镜）。

专家辩论：人类如何找到首例的外星生命？

明日的图片：open space