Saturn is the sixth planet in our Solar system. It is the second-largest planet of the Solar system and perhaps the most popular, due to its magnificent ring system. Saturn has been identified as a planet around the 7-8 century BCE by Babylonian Astronomers. Its name comes from Saturn, the Roman god of wealth and agriculture. Just like Jupiter, Saturn is a gas giant, thus, the planet has no solid surface. Apart from the beautiful ring system, is there anything else on Saturn? Let’s see below all the interesting facts about Saturn.
Saturn planet information
Saturn orbits the Sun at a mean distance of 1,514.5 millions km (i.e., this is ten times the distance between the Earth and the Sun). The planet needs 29.45 years to complete an orbit around the Sun, but one day in Saturn is only 10 hours, 45 minutes and 45 seconds (only Jupiter rotates faster). Saturn’s rotation axis is tilted by 26.73° degrees with respect to its orbital plane (Earth is tilted by 23.2° degrees), meaning that the planet has seasons.
Saturn has a mean radius of 58,232 km (~ 9.5 times larger than Earth) and a mass of 5.68 ×1026 kg (~ 95 times Earth’s mass). The mean density is ~ 0.687 g/cm3. Thus, if you find a large enough pool, Saturn would be floating there. Finally, the gravitational acceleration in Saturn is 1.065 g (i.e., similar to Earth).
The temperature of Saturn increases significantly, as you go into its interior, thus at a pressure of 0.1 bar it is -189°C (-308°F), while at 1 bar level it is -139°C (-218°F). In case you think this is still cold, near the core of Saturn, the temperature is at least 11,300 °C (~21,100°F).
Apart from being the lord of the rings, Saturn is also the planet with the highest number of satellites. So far, we know 82, and there are others that await confirmation.
Structure of Saturn
When you see images of Saturn, what you actually see are the upper layers of its atmosphere. The most interesting feature of Saturn’s atmosphere is definitely the super-fast winds that can reach up to 1,800 km/h (1,100 m/h). The energy-source of these winds is heat from the planet’s interior. Thus, warm gases rise to the upper layers of the atmosphere, until they cool down and eventually freeze, forming ice particles. Finally, the yellow color that is dominant in Saturn’s atmosphere is from ammonia ice that reflects sunlight.
Based on the current planetary models, it is commonly accepted that Saturn’s interior is similar to that of Jupiter. Thus, Saturn most likely has a small rocky core (similar to Earth in composition but denser), surrounded by hydrogen and helium and small traces of other gases like methane and ammonia. The core has a mass between 9–22 times the mass of Earth, which translates to a maximum core radius of 12,000 km. Around the core there is a thick layer of liquid metallic hydrogen, that is followed by a layer of liquid helium and molecular hydrogen, which transits to gas with increasing altitude. Finally, the outer layer of gas (i.e., what we can see on Saturn through images), extends for around 1,000 km.
The rings of Saturn
Saturn’s rings out sign everything else on the planet. The planet has the most extensive ring system amongst all planets in the Solar system, and it’s the feature that made Saturn one of the most popular objects in the night sky. The ring system was discovered in 1655, by the Dutch astronomer Christiaan Huygens, when he reported a disk structure (i.e. one ring) around the planet. Furthermore, in 1675 Italian astronomer Giovanni Domenico Cassini, determined that Saturn’s ring is composed of multiple smaller rings with gaps between them. The largest gap was named the Cassini Division in his honor.
The ring-particles are mostly water ice, together with a small amount of rocky material. The main rings are made out of particles that vary in size from one centimeter to 10 meters, while their thickness ranges between 10 meters to one km.
Using measurements from the Cassini probe, scientists have estimated a mass of 1.54×1019 kg for the ring system. This corresponds to a mass equal to half the ice mass that is in Antarctica. The difference is that it is distributed over a surface 80 times greater than the surface of the Earth.
The ring names are given by letters (i.e., A, B, C, etc), based on their discovery. The D ring is the one that lies closest to the planet, located at a distance of 67,000 km from the center (it has a width of 7,500 km), while the most outer ring (i.e., E ring) has a width of 300,000 km, and it is located at a distance of 180,000km from the center.
The age and the formation of the rings are still not clear. Thus, depending on the approach, the rings could be as old as Saturn is, but on the other hand, they could be a much younger structure forming 10-100 million years ago. For the formation again, the view is also not really clear. According to a model, the ring system formed by a satellite of Saturn, that was destroyed due to tidal forces. The alternative model assumes the ring system has formed from the mantle of a satellite after a tremendous impact by an asteroid.
Satellites of Saturn
Saturn has 82 known moons, and 53 of them have formal names. Over the next post, we will go through the moons of Saturn, and see why they have attracted our interest. To give some hints, we will see a thick atmosphere, lakes, cryovolcanoes, the possibility of a ring around a moon, a blockbuster and gaming.
Exploration of Saturn
The first probe that flew by Saturn was Pioneer 11 in September 1979. The first high-resolution images were taken in November 1980 when Voyager 1 visited Saturn. The probe also returned important information on the moons of Saturn. Nearly a year later, Voyager 2 flew by, and the returned images provided evidence of changes in the atmosphere and the rings.
The most detailed data were obtained by the Cassini-Huygens probe, when it entered orbit around Saturn on the 1st of July 2004. It also captured images from Titan’s surface (Saturn’s largest moon), revealing large lakes with numerous islands and mountains. Cassini, after two flybys on Titan, released the Huygens probe on the 25th of December 2004, which landed Titan on the 14th of January 2005.
Between 2004 and 2009, Cassini discovered eight new satellites that orbit Saturn. The 15th of September 2017, was the last day of the probe, when it entered the atmosphere of the planet, thus ending its mission.
Fun facts about Saturn
- You can see Saturn without a telescope
- The rings of Saturn contribute to its brightness, but they cannot be seen by the unaided eye.
- Saturn’s distance from the Sun is two times the distance between Jupiter and the Sun.
- Saturn radiates 2.5 times more energy into space than it receives from the Sun.
- When Galileo observed Saturn in 1610, he was unable to resolve the rings of Saturn due to the poor quality of his telescope. Thus, he thought that Saturn was more than one planet.
- Saturn has a strong magnetic field, and we can observe auroras on its poles.
- Saturn’s lightnings are 1,000 times stronger than those on Earth.
- A hurricane on Saturn are 20 times larger than those on Earth.
- Saturn’s hexagon, is a cloud pattern has been detected on the north pole of the planet. The sides of his structure are 14,500 km long. The width of the hexagon is broader than 29,000 km across, and most likely is a jet stream of gases that move at a speed of 320 km/h.