天文学家在距离地球不远处发现一颗与地球绕日轨道相同的小行星

心灵

天文学家在距离地球不远处发现一颗与地球绕日轨道相同的小行星。

The 200-300m-wide rock sits in front of our planet at a gravitational "sweet spot", and poses no danger.

这块200-300米大的星体位于我们星球前方一个重力平衡点上，不对地球构成任何危险。

Its position in the sky makes it a so-called Trojan asteroid - a type previously detected only at Jupiter, Neptune and Mars.

它在天空的位置使其被称为特洛伊小行星 ——此前仅在木星、海王星和火星探测到的一种类型

2010 TK7, as it is known, was found by Nasa's Wise telescope. The discovery is reported in this week's Nature journal.

美国航空航天管理局（NASA）的“智慧”卫星望远镜发现了这颗被称为2010 TK7的小行星。本周出版的《自然》杂志中报道了这一发现。

It is a fascinating observation because the relative stability and proximity of Trojans would make possible targets for astronaut missions when we eventually go beyond the space station.

这是一项令人着迷的观测结果，因为当我们最终超越空间站后，特洛伊小行星相对稳定和距离接近的特点使其成为宇航员太空任务的可能目标。

2010 TK7 is probably not the rock of choice, simply because it travels too far above and below the plane of Earth's orbit, which would require a lot of fuel to reach it.

但2010 TK7可能不会被选为目标星体，因为它的行进偏离地球轨道平面的距离过大，使得抵达它需要耗费大量燃料。

Nonetheless, its detection means it is highly likely there are other, more suitable Trojans out there waiting to be found.

不过，这一发现意味着很可能存在着其他更合适的特洛伊小行星有待发现。

The difficulty is the viewing geometry that puts any Trojan, from the perspective of an Earth-based telescope, in bright skies.

观测特洛伊小行星的难点在于，在通过地面望远镜观测时，几何角度总是使其位于明亮的天空中。

It took an orbiting telescope sensitive to infrared light to pick up 2010 TK7.

使用一架可感知红外线的太空轨道望远镜才最终看到了2010 TK7。

Wise, the Wide-field Infrared Survey Explorer launched in 2009, examined more than 500 Near-Earth Objects (NEOs), 123 of which were new to science.

广谱红外勘测探索卫星（简称“智慧”）于2009年发射升空，已检测了超过500个近地天体，其中123个属于新的科学发现。

The authors of the Nature paper sifted through data on these rocks, looking for the candidates that might be Trojans.

《自然》杂志论文的作者筛选了这些天体的数据，搜寻可能存在的特洛伊小行星。

Follow-up work on the Canada-France-Hawaii Telescope confirmed the status of 2010 TK7.

加拿大-法国-夏威夷望远镜（CFHT）设施的后续观测证实了2010 TK7的身份。

It traces quite a complex path at its orbital point. Currently, it is about 80 million km from Earth, and should come no closer than about 25 million km.

该小行星在轨道上沿着相当复杂的路径移动，目前，它距离地球大约8000万公里，最近时不会小于2500万公里。

The team says its orbit appears stable at least for the next 10,000 years.

研究团队称，看起来它运行轨道至少会在未来10000年内保持稳定。

2010 TK7's existence should not really be a surprise. Jupiter, Neptune and Mars all have collections of rocks sitting in the so-called Lagrange points 60 degrees ahead of or behind the planets in their orbits.

2010 TK7的存在并非意外。木星、海王星和火星在其轨道前方60度或后方60度的所谓“拉格朗日点”上均有一批这样的石块。

In the case of Jupiter, the number of Trojans now tops 1,000 rocks.

目前木星的特洛伊小行星数量超过1000个。

"These objects are difficult to find from Earth, simply because they're not very big and they're pretty faint, and they're close to the Sun as seen from Earth," explained Christian Veillet from the Canada-France-Hawaii Telescope and a co-author on the Nature study.

供职于加拿大-法国-夏威夷望远镜设施、该《自然》论文撰写人之一克里斯琴·威利特(Christian Veillet)解释说：“这些天体从地球上很难发现，因为它们体积不大，很暗淡，并且在地球上看去靠近太阳。”

"But we can find them from space, and future satellites will likely find some more. We think that there are others which will be very close to the Earth and have motions that make them relatively easy to reach. So, they could be potential targets to go to with spacecraft," he told BBC News.

他告诉BBC新闻频道：“但我们能够从太空中找到它们，未来的人造卫星将可能会发现更多。 我们相信存在一些非常靠近地球而且运动方式适宜到达的特洛伊小行星，这样，它们可能会成为飞船前往的潜在目标。”