Our solar system is vast and the planets in it are each extraordinary in their own way. Some are big, some are small, some are rocky and others are gassy.

Swipe through to learn interesting facts about the planets in our solar system.

Mars is Really Cold

One planet that’s further from the sun than Earth is Mars, and it’s very cold. The entire plane is as cold as Earth’s South Pole, which is normally about -76 degrees Fahrenheit. Both its distance from the sun and its thin atmosphere contribute to its chilliness.

Water on Jupiter’s Big Moon

Ganymede is Jupiter’s biggest moon—bigger than Mercury—and its huge, salty ocean contains more water than all the water on Earth. Ganymede’s ocean is thought to be 60 miles thick, which is 10 times deeper than Earth's oceans.

6 Dwarf Planets

Depending on how old you are, you may have been taught that there are 9 planets in our solar system. Then in 2006, Pluto was declared a “dwarf planet.” Well, as it turns out, there are five other dwarf planets in our solar system, including one discovered in 2015. The new one’s official name is TG387 but it’s nicknamed “The Goblin.”

Some Planets Are Mostly Gas

Jupiter, Saturn, Uranus and Neptune don’t have solid surfaces. Their rocky core is surrounded by hydrogen and helium. Together these four gas giants are known as the Jovian planets and they are much larger than Earth and the other terrestrial—aka “rocky”—planets.

Pluto is Mountainous

Scientists assumed Pluto would be flat with a few craters, but were surprised to discover a few years ago that the dwarf planet has mountains, some rising as high as 11,000 feet. According to NASA, the mountains are “probably composed of Pluto’s water-ice bedrock. ”

Mars Has a Huge Volcano

Comparable to the size of Arizona, Olympus Mons on Mars is the biggest volcano ever discovered in the solar system. It’s 16 miles high—triple the height of Mount Everest. It’s, by volume, 100 times bigger than Mauna Loa, Earth’s largest volcano.

Saturn's Rings are 90% Ice

Saturn’s position at 898.61 miles from the sun makes it extremely cold as well. It’s so cold, in fact, that its rings, which are composed of 90% water, are frozen into ice. Incidentally, Saturn isn’t the only planet with rings—the other gas planets have rings that are less visible.