Starship Asterisk*

Few missions have visited Saturn: Pioneer 11 and Voyagers 1 and 2 flew by; But Cassini orbited Saturn 294 times from 2004 to 2017.

Saturn has the most spectacular ring system, with seven rings and several gaps and divisions between them.

Saturn has 53 known moons with an additional 29 moons awaiting confirmation of their discovery—that is a total of 82 moons.

Saturn's atmosphere is made up mostly of hydrogen (H2) and helium (He).

Saturn is a gas-giant planet and therefore does not have a solid surface like Earth’s. But it might have a solid core somewhere in there.

Saturn takes about 10.7 hours (no one knows precisely) to rotate on its axis once—a Saturn “day”—and 29 Earth years to orbit the sun.

Saturn is the sixth planet from our Sun (a star) and orbits at a distance of about 886 million miles (1.4 billion kilometers) from the Sun.

Nine Earths side by side would almost span Saturn’s diameter. That doesn’t include Saturn’s rings.

Mars is known as the Red Planet because iron minerals in the Martian soil oxidize, or rust, causing the soil and atmosphere to look red.

At this time, Mars' surface cannot support life as we know it. Current missions are determining Mars' past and future potential for life.

Several missions have visited this planet, from flybys and orbiters to rovers on the surface.The first true Mars mission success was the Mariner 4 flyby in 1965.

There are no rings around Mars.

Mars has two moons named Phobos and Deimos.

Mars has a thin atmosphere made up mostly of carbon dioxide (CO2), argon (Ar), nitrogen (N2), and a small amount of oxygen and water vapor.

Mars is a rocky planet. Its solid surface has been altered by volcanoes, impacts, winds, crustal movement and chemical reactions.

One day on Mars takes a little over 24 hours. Mars makes a complete orbit around the Sun (a year in Martian time) in 687 Earth days.

Mars orbits our Sun, a star. Mars is the fourth planet from the Sun at an average distance of about 228 million km (142 million miles) or 1.52 AU.

If the Sun were as tall as a typical front door, Earth would be the size of a dime, and Mars would be about as big as an aspirin tablet.

Our atmosphere protects us from incoming meteoroids, most of which break up in our atmosphere before they can strike the surface.

Earth is the perfect place for life as we know it.

Many orbiting spacecraft study the Earth from above as a whole system—observing the atmosphere, ocean, glaciers, and the solid earth.

Earth has no rings.

Earth has one moon.

Earth's atmosphere is 78 percent nitrogen, 21 percent oxygen and 1 percent other ingredients—the perfect balance to breathe and live.

Earth is a rocky planet with a solid and dynamic surface of mountains, canyons, plains and more. Most of our planet is covered in water.