All of the Sun’s major planets are a bit flattened – they’re bigger through the equator than through the poles. For Mercury and Venus, the difference is only a few miles. For Earth, it’s about 20 miles. But for Saturn, it’s more than seven thousand miles. Such a big difference is obvious even to the eye alone: The giant planet looks like a squashed beachball.

The planets are flattened because they’re spinning. The rotation pushes material outward. Solid bodies like Earth are stiff, and they don’t rotate all that fast, so they’re not deformed by much. But Saturn and the other giant worlds don’t have solid surfaces. That makes it easier to push stuff away from the center as the planet spins.

Saturn is flatter than the other giants. That’s mainly because it’s less dense than the others. That means its surface gravity isn’t as strong, so it doesn’t grip material at the surface as tightly.

And Saturn spins in a hurry – roughly once every 10 and a half hours, although the exact timing is still uncertain. That means the planet’s equator rotates at more than 21,000 miles per hour – 20 times faster than Earth’s equator. That slings material outward with great force – making Saturn the most “smushed” planet in the solar system.

Look for Saturn near the crescent Moon early this evening. The planet looks like a bright star above the Moon as twilight fades. They set a couple of hours after sunset.

Script by Damond Benningfield