木星这么大,它其实并不绕着太阳运转。
One of my daughter's favorite books is "Space Walk" by Salina Yoon. Each page shows a planet accompanied by a rhyming factoid about it.
我女儿最喜欢的书之一是Salina Yoon的“太空漫步”。每页显示一个行星，并伴随着一个关于这颗行星的押韵的要素。
But each time I read it to her — sometimes three or more times a day — I furrow my nerdy brow at this line: "Of all the planets that circle the sun, giant Jupiter is the biggest one.”
但每次我给她读这本书时-有时一天要读三或更多次——一到这一行，我这个书呆子的眉头就会皱起来:”在所有的、围绕太阳运转的行星中，那个巨大的木星是最大的一个。“
The gas giant is indeed the largest planet in the solar system, weighing more than twice the mass of all the other planets, moons, asteroids, comets, and more combined.
这个气体巨人的确是太阳系中最大的行星，它的重量比其他行星、卫星、小行星、彗星的质量的总和两倍还要多。
However, Jupiter does not technically orbit the sun — because it's so dauntingly massive.
然而,木星在理论上说并不绕太阳运行--因为它大得吓人。
When a small object orbits a big object in space, the less massive one doesn't travel in a perfect circle around the larger one. Rather, both objects orbit a combined center of gravity.
当一个小天体绕着太空中的一个大物体公转时，体积较小的物体就不会在大的天体周围进行完美的圆周飞行。相反,两个物体都围绕着一个合并的重心旋转。
For a puny, fragile planet like Earth, which is 0.000003 the mass of the sun, the center of gravity resides so close to the center of the sun that we don't even notice the slightly off-kilter orbit. It seems as though we circle the star.
对于一个弱小的、脆弱的行星来说，诸如地球是太阳的质量的0.000003，重心的位置接近太阳的中心，我们甚至觉察不到有些许的出轨运行。所以看起来好像我们绕着星星转。
The same is true of most other objects in the solar system — except Jupiter.The gas giant is so big that it pulls the center of mass between it and the sun, also known as the barycenter, some 1.07 solar radii from the star's center — which is about 30,000 miles above the sun's surface.
除了木星之外,太阳系中大多数其他天体也是如此。然而这个气体巨人是如此之大,它把它和太阳之间的质量中心，也称为质心，拉到距这个恒星的中心约1.07太阳半径的距离-这是差不多离太阳表面3万英里以外的距离。
Jupiter is about 0.001 as massive than the sun, but it's sizeable enough that both the sun and Jupiter orbit that point in space.
木星是太阳质量的0.001左右，但它的规模足以使太阳和木星围绕着这个在太空中的质心点旋转。
Essentially, that's how Jupiter and the sun move through space together — though the distances and sizes are far different.
本质上,这就是木星和太阳如何在空间中移动，尽管它们的距离和大小是截然不同的。
So the next time you read a kid's book that says that Jupiter circles the sun, you'd be forgiven for trying to rip out that page. Just like my daughter enjoys doing.
所以，下一次你读到一本孩子的书，说木星绕着太阳转，就像我女儿喜欢做的那样，如果你要撕掉那一页的话是是完全的情有可原的。
来源：本文原载于“充满阳光的房间”微信公众号，为该公众号的原创作品，转载已获得授权。
（编辑:jilihua）
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