Astronomers¹ have announced the possible discovery of the first known moon outside our Solar System.

天文学家日前宣布，他们可能在我们的太阳系外发现了第一颗已知的月球。

This "exomoon" is not like any in our cosmic neighbourhood: it's the size of Neptune² and orbits a planet the size of Jupiter -- but with 10 times the mass.

这颗“系外月球”与我们宇宙里的任何东西都不同：它的体型有海王星那么大，绕着一颗木星大小的行星旋转--但这颗行星的质量是木星的10倍。

The object was spotted³ in data from Nasa's Kepler spacecraft⁴, and later observed using the Hubble telescope.

在该星体纳入美国宇航局开普勒探测器的数据后，天文学家使用哈勃望远镜进行了观测。

Astronomers David Kipping and Alex Teachey have published their results in Science Advances journal.

天文学家戴维·基平和阿莱克斯·提彻已将他们的成果发表在《科学进展》杂志上。

But they say that further observations are needed to understand the distant planetary system.

但是他们表示，需要进一步的观察才能理解这个遥远的行星系。

"We've tried our best to rule out other possibilities such as spacecraft anomalies, other planets in the system or stellar activity, but we're unable to find any other single hypothesis which can explain all of the data we have," said Dr Kipping, from Columbia University in New York.

来自纽约哥伦比亚大学的基平博士称：“对所观测到的现象，我们已尽力排除其他可能性，如探测器异常、太阳系中的其他行星或恒星活动，但我们无法找到任何其他单一假设来解释我们的数据。”

To date, astronomers have discovered more than 3,500 exoplanets -- worlds orbiting stars other than the Sun.

迄今为止，天文学家已发现超过3500颗系外行星--即环绕除太阳以外运行的星体。

A hunt for exomoons -- bodies that orbit these distant planets -- has proceeded in parallel. But so far, these natural satellites have lingered at the limits of detection with current techniques.

天文学家也在同时寻找“系外月球”--即围绕遥远行星的星体。但到目前为止，这些天然星体很难被现有技术的探测到。

The researchers monitored a planet known as Kepler 1625b as it passed in front of its parent star.

研究人员是在这颗被命名为开普勒1625b的星体环绕其母星运行的时候，对其进行的监测。