科学家发现“第二太阳系” 距离发现另一个地球还远吗

Nasa has found a distant star circled by eight planets, equal to the complement in our own Solar System. It’s the largest number of worlds ever discovered in a planetary system outside our own.

美国宇航局正式宣布,在一个恒星周围发现有8颗行星组成的行星系统，我们生活的太阳系一直以来都是围绕单个恒星周围已知行星数量最多的案例，这是首次发现除太阳系外，行星数量最多的星系。

The star known as Kepler-90, is just a bit hotter and larger than the Sun; astronomers already knew of seven planets around it. The newly discovered world is small enough to be rocky, according to scientists." This makes Kepler-90 the first star to host as many planets as our own Solar System," said Christopher Shallue, a software engineer at Google, which contributed to the discovery.

这颗恒星名为“开普勒90”，比太阳要更大、更热，天文学家之前已知道有7颗行星环绕其运行。据科学家称，这次新发现的行星是一小型的岩石行星。参与此次发现的，谷歌软件工程师克里斯托佛称，这也使这一系统中行星体的数量达到了与太阳系相同的水平。

Engineers from Google used a type of artificial intelligence called machine learning to find planets that were missed by previous searches. The discovery was based on observations gathered by Nasa’s Kepler Space Telescope. Its parent star is very distant, lying 2,545 light-years away. But its planetary system appears to be ordered in a similar way to our own.

本次发现的另一个亮点在于，这一成果借助谷歌公司的机器学习技术获得，这些技术可以发现以前错过的一些行星。在最新研究中，计算机学会了如何从开普勒获得的系外行星发出的信号数据中找到行星。这个星系的恒星距离非常遥远，大概有2545光年遥远，但这个星系是最像太阳系的。

Andrew Vanderburg, a co-discoverer at the University of Texas at Austin, said: "The Kepler-90 star system is like a mini version of our Solar System. You have small planets inside and big planets outside, but everything is scrunched in much closer."

德克萨斯大学奥斯汀分校的范德伯格教授，也参与了此次发现，他称，“开普勒90”像是一个“迷你太阳系”，越靠近恒星的行星越小，越远的行星越大，只不过他们之间的距离更近。

To give a sense of how close, the outermost planet in the system orbits at around the same distance the Earth does from the Sun. Because the new world, dubbed Kepler-90i, is so much further in - it completes one circuit of its star every 14.4 days - it’s estimated to have a scorching hot surface temperature of around 425C.

到底多近呢，最远的行星也就地球离太阳那么远。“开普勒90”的星系如此紧凑，它公转周期仅有大约14.4天，其地表温度极高，达到426摄氏度以上。

The machine learning technique was also used to find a new Earth-sized planet, called Kepler 80g, around a different star. Some 3,500 exoplanets - worlds circling other stars - have been documented in recent decades.

此次还发现了一个和地球同样大小的行星， Kepler 80g，来自于另外一个星系。此外，最近十年，还有大概3500个其他星系的行星被发现。