SATURN

The ringed wonder.

Saturn is the second largest planet in the solar system, surpassed only by Jupiter. Don’t think that puts Saturn in the mid-tier, though. It’s still an absolute giant, measuring more than twice the diameter of its ice giant cousins, Uranus and Neptune, and nine times the diameter of Earth. By volume, you could fit 764 Earths inside it. Despite its enormous size, Saturn is surprisingly lightweight. It’s 97 times the mass of Earth, which is no doubt a lot, but it’s less than a third the mass of Jupiter. Amongst all the combined mass of the solar system’s planets, Saturn accounts for about 20%. Saturn is actually the least dense planet in the solar system.

Fun fact: Saturn is the only planet that is less dense than water. If you had a big enough bathtub, Saturn would float in it. Don't take this too literally, though.

Like Jupiter, Saturn rotates very fast. Saturn’s rotation trails Jupiter’s by only about a half an hour, the second fastest rotation in the solar system. The centrifugal force produced by this rapid rotation also causes Saturn to bulge in the middle. Saturn is much less dense and has weaker gravity than Jupiter, so despite rotating slightly slower, Saturn can’t hold in its material as tightly and thus its equatorial bulge is more prominent. Saturn is wider at the equator compared to its pole-to-pole diameter by 11,800 km (7,330 mi). Saturn is the most flattened planet in the solar system.

Saturn is a gas giant, meaning it is a colossal sphere composed almost entirely of hydrogen and helium gas. Of course, the reality is more complicated than that, but you may notice how closely this description also applies to the Sun.  Granted, the Sun is 1,600 larger in volume and 3,500 times more massive than Saturn. Regardless, both are composed predominantly of the same two elements. It makes sense that the gas giants most resemble the Sun considering they formed from the same gas and dust of a collapsing nebula and emerge relatively soon after the Sun itself. Because the gas giants were earliest, they got first dibs on the most abundant elements.

Has belts and zones too but they are not as contrasting because they occur deeper in the atmosphere.

Equatorial bands (brighter: beige, pale yellow, butterscotch)

Tropical and temperate bands (darker: golden brown, tan)

Polar bands (dark brown, slate, cool or cornflower blue)

Hemispheres are golden in the summer and blue in the winter.

Storms

Very few things in the night sky have captured the imagination of people across the world, both children and adults alike, as the majesty of Saturn. The last and most distant of the classical planets, Saturn has been known to humanity since prehistoric times. It is indeed the farthest planet that can be reliably seen with the naked eye and, consequently, generally the dimmest of the classical planets, though it occasionally outshines Mercury. It appears as a beige point of light with an apparent brightness that generally falls between that of the stars, Vega and Fomalhaut. It could be easily mistaken for a star, but when you look at it through even a modest backyard telescope, it is transformed into one of the most awe-inspiring views in all of astronomy. The planet’s magnificent rings and even one or more of its moons can be easily observed! The look on people’s faces when they see Saturn with their own eyes for the first time just never gets old.

Of the classical planets, Saturn moves across the night sky the most sluggishly. Today, we understand this as a function of its farther distance, but for ancient people, it was just Saturn’s nature. Its slow passage through the heavens led them to associate Saturn with the slow passage of time. For Romans, Saturn was an agricultural deity that signaled the coming of a bountiful harvest. For Greeks, Saturn was Cronus, who was not only the father of Zeus (just as Saturn supersedes Jupiter) but consumed each of his children at birth just as time consumes all else. Cronus, by the way, later became associated with Chronos, the personification of time.

Pictured: Low-angle view of Saturn’s cloud tops imaged by NASA’s Cassini orbiter in 2006. At the top of the image, you can see Saturn’s rings. Credit: NASA/JPL-Caltech/Jason Major