As a planet, it's been called Tyche or simply Planet X.

它曾被当作行星命名为堤喀或者简单的X行星。

He died long before the search for Planet X resulted in the discovery of Pluto.

早在寻找行星X并最终发现冥王星之前，他就去世了。

However, the first search failed. In fact, he failed to recognize Planet X in a few photographs.

但是，第一次搜寻失败了。实际上，他没能在一些照片中认出X星球。

The unknown planet X, X marks the spot of unknown treasure, and now nerds' love of X has grown beyond the unknown.

未知的行星 X，X 标志着未知宝藏的地点，现在书呆子对 X 的爱已经超越了未知。

They call it Planet X, and believe it is the size of Neptune.

他们称它为 X 行星，并认为它有海王星那么大。

Also known as Planet Nine, Planet X won't have an official name until someone can prove without a shadow of a doubt that it's actually there.

也被称为第九行星，X 行星不会有正式名称， 直到有人可以毫无疑问地证明它确实存在。

A few astronomers continue to think there may be a Planet X out there a real whopper, perhaps as much as ten times the size of Jupiter, but so far out as to be invisible to us.

现在，有的天文学家继续认为，冥王星之外也许还有行星X一颗真正的庞然大物，也许有木星的10倍之大，只是它太遥远，我们看不见。