Yes, six planets will be visible in the January night sky. And yes, they'll be in a line. But because planets always appear in a line from our Earth-bound vantage, the alignment isn't anything out ...

A planet-size object that possibly once visited the solar system may have permanently changed our cosmic neighborhood by warping the orbits of the four outer planets, a new study suggests.

Kuiper Belt, well past the orbit of Neptune (artistic illustration). There may be an undiscovered planet in the outer solar system whose presence is revealed by the strange orbit of objects beyond ...