Speaking of which, it's time to test your knowledge of our stellar neighborhood with our solar system quiz. If you need a hint, click the yellow button. —Black hole quiz: How supermassive is ...

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.

Need a new idea to keep kids entertained? Try stargazing. Free learning activities and videos about the solar system Free learning activities and videos about the solar system Free learning ...