No other planet in our solar system elicits as much awe and wonder, as does Saturn. Ask any astronomer who has ever given someone a view of it through a telescope. Invariably the response is “Oh my god!” or “That can’t be real!” With its golden hue and glorious ring system Saturn looks like a celestial Christmas ornament suspended against the black backdrop of space.
Located some 885,904,700 miles from the Sun, Saturn is our second largest planet with a diameter of 74,898 miles. It is one of the gas giant worlds, just like Jupiter, and is composed mostly of hydrogen and helium with high altitude ammonia ice clouds in its upper atmosphere.
Beneath this dense soup of gases the pressure becomes so great that the hydrogen turns to liquid and deeper still the hydrogen becomes a weird, electrically conducting liquid metallic hydrogen. At its core there may exist a molten mix of rock and metal. All in all, the density of Saturn is less than that of water and it has been said that if you could find an ocean large enough the planet would float on top of it.
Jupiter, Saturn, Uranus, and Neptune all have rings but none are as spectacular as is Saturn’s. With a total diameter of 170,000 miles the complex ring system is made up of billions of pieces of ice. Some are no bigger than grains while others are the size of a house. The rings are actually made up of a multitude of ringlets. Tiny moons within the rings carve out gaps and create complex structures within the ring plane. Remarkably, the ring plane is quite thin in some places, about 30 feet or so, while in others it can be almost a mile thick. We don’t know yet exactly how this incredible structure formed but the best working model we have is that an icy moon strayed too close to Saturn and became shredded by its gravity.
There are a total of 62 satellites orbiting Saturn and they are fascinating worlds in their own right. Titan is the largest at 3,200 miles across, larger than Mercury or the dwarf planet Pluto. It’s a rather chilly -292 degrees Fahrenheit at the surface and any water there exists as ice hard as granite. Titan is the only moon in the solar system with a substantial atmosphere, denser than our own. It’s composed mostly of nitrogen, methane, and ammonia. While far too cold for liquid water to exist Titan’s atmosphere does allow for methane (which exists as a gas here on Earth) to precipitate out of the clouds as liquid. Huge lakes of the stuff exist at the surface. Weirder still is evidence of volcanoes on Titan but rather than molten lava we’d see slushy ice pouring out of them. By all rights you’d think the smaller moons would be frozen solid but one, Enceladus, gets pulled and stretched so much by the gravity of Saturn and the other moons that its core gets heated up from all the friction. This melts the ice beneath it’s icy exterior but the pressure builds up and the water has to go somewhere.
NASA’s Cassini spacecraft has imaged geysers of water and vapor spewing out of cracks in the moon’s surface. Some of this rains back down as snow while some of it is ejected out into space where it goes into replenishing a tenuous outer ring of Saturn. Titan and Enceladus are potential targets in our hunt for life elsewhere in the solar system.
This month is a great time for seeing Saturn with just your naked eye but the best night will be on May 22 when the planet reaches opposition at 9 p.m. CDT. An outer planet is said to be at opposition when it is exactly opposite the Sun as seen from Earth. In other words, if you were “above” the solar system and looking “down” you would see a configuration like this: Saturn->Earth->Sun. When this happens the planet is at its best for viewing because it is at its closest to Earth and because it can be seen almost all night. But, to be honest, Saturn will look just dandy all month long.
By the middle of the month Saturn rises above the southeastern horizon around 9pm and reaches its highest point in the sky by midnight; but it won’t climb very much higher above the horizon.
It will appear as a bright, golden-looking star and just beneath it you will see the red supergiant star Antares, the brightest star in the constellation of Scorpius. As an added bonus, if your sky is really dark you can just make out a pale band of light running from an area below Antares and back off to the east/northeast: this is the Milky Way. The Milky Way will look best after midnight and will become more conspicuous in our summer sky as the months wear on.
During much of May Saturn will appear the brightest it’s been in 8 years. This is because the planet’s northern hemisphere and rings are tilted by about 24 degrees towards Earth right now. This means that the ice in those rings are reflecting a lot more of the Sun’s light our way and so the planet appears all the brighter.
You will need a small telescope to see the rings but a pair of binoculars will reveal Saturn as a bulgy-looking disc. This thickness in the midsection is actually the rings themselves but the binoculars just don’t have enough power to resolve them into a clear image. Some binoculars may also show you Saturn’s largest moon, Titan, as a star-like speck nearby.
Darrell Heath works at the University of Arkansas at Little Rock and is a producer and host for the UALR Television show “The Night Sky.”