Only Jupiter is larger than this gas giant, best known for its ring system!
We’ve been viewing Saturn with the naked eye since prehistoric times, but the planet’s most unique feature – its ring system -wasn’t discovered until 1610.
Each ring contains billions of chunks of dust and water-ice. Saturn has about 14 major ring divisions, but there are also satellites and other structures within some of the rings and gaps. Saturn’s rings are believed to have come from the remains of moons, comets or other bodies that broke up in the planet’s atmosphere.
The rings aren’t the only fascinating thing about Saturn, however. This gas giant is less dense than any other planet in our solar system and has a mostly fluid structure. It radiates a massive amount of energy, thought to be the result of slow gravitational compression.
Saturn takes about 29.5 years to revolve around the Sun, and its rotation is a bit more complex – different probes have estimated different times, the latest estimate is ten hours, 32 minutes and 35 seconds. The variations probably have something to do with irregularities in the planet’s radio waves, due to the similarities between its magnetic axis and its rotational axis.
Saturn has a cold atmosphere comprising layered clouds of both water-ice and ammonia-ice. It also has winds of up to 1,800 kilometres per second. Occasionally Saturn has storms on its surface, similar to those of Jupiter. One such storm is the Great White Spot, a massive storm in the planet’s northern hemisphere that has been observed about once every Saturnian year since 1876.
Rings in view
Saturn takes 29.5 years to orbit the Sun, and it has an elliptical orbit like most planets. The closest Saturn comes to the Sun is 1.35 billion kilometres, while at its furthest, Saturn is 1.5 billion kilometres away. Saturn has a tilt of 26.7 degrees relative to the orbital plane. During half of its orbital period, the northern hemisphere is facing the Sun, while the southern hemisphere faces the Sun during the other half. When viewing Saturn from Earth, this impacts whether we can see the rings full-on or as a thin line.
Discovering the rings
Galileo thought that he was seeing moons orbiting Saturn instead of rings because his telescope was not powerful enough. Astronomer Christiaan Huygens observed the rings in 1655, but thought they were a single ring.
In 2004, the Cassini space probe discovered a massive, oddly shaped convective thunderstorm in Saturn’s southern atmosphere. Dubbed the Dragon Storm, this weather feature emitted strong radio waves. Like storms on Earth, the Dragon Storm emits flashes of lightning that appear as white plumes. Scientists believe it exists deep in the atmosphere and can occasionally flare up.
Facts about Saturn
Inner core – The inner core is likely very small and contains silicate rock, much like Jupiter’s core.
Outer core – Saturn’s outer core is much thicker than its inner core, containing metallic liquid hydrogen.
Rings – Saturn’s rings comprise particles of ice and dust that range from microscopic to several thousand kilometres in diameter.
Inner layer – This thickest layer surrounding the core is liquid hydrogen and helium.
Outer layer – The outer layer is gaseous hydrogen and helium, blending with its atmosphere.