The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

But the auroras on Uranus prove that the lights are beautiful anywhere in the solar system, appearing as thin streaks of bright white light set against the deep azure background of the planet.

“Our Solar System’s Kuiper Belt long appeared to ... for objects was complicated by being located in front of the dense background of the galaxy’s center. But now that it’s located in ...