Test your knowledge on our solar system, from the biggest and smallest planets to the behemoth mountain on Mars.

Encountering Neptune in 1989, NASA’s Voyager mission completed humankind’s first close-up exploration of the four giant outer ...

Encountering Neptune in 1989, NASA's Voyager mission completed humankind's first close-up exploration of the four giant outer ...

Jupiter, the largest planet in the solar system, will be visible to sky gazers on Earth. Here’s when to look out for it and ...

For billions of years, it's kept our ... solar system. The solar system is approximately 4.6 billion years old. Astronomers believe that roughly 100 million years into its existence, the planets ...

For billions of years, it's kept our ... planets out of their original orbits — showing that perhaps not even the Sun can protect us from the chaos caused by foreign intruders. The solar system ...