Star Watch: Saturn reigns

Published 1:01 pm Sunday, May 29, 2016


By Deane Morrison

University of Minnesota

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Saturn has been playing second fiddle to Mars all year, but in June the red planet fades while the ringed planet reaches its pinnacle.

Saturn’s big moment comes overnight on the 2nd-3rd, when Earth laps it in the orbital race. At that time Saturn will be opposite the sun in the sky and up all night. Also, its rings are now very favorably tilted for telescopic viewing.

They were well tilted in 1610, too, when Galileo discovered them. His telescope couldn’t resolve their structure, and he thought Saturn was sandwiched between two close—and gigantic—moons. Later, as Earth passed through the ring plane, the rings turned edge-on and disappeared, adding to his confusion. In 1659 Dutch astronomer Christiaan Huygens, benefiting from a better telescope, published his theory that Saturn was encircled by a ring. But it wasn’t until the 1850s that the Scottish physicist James Clerk Maxwell showed, using mathematics, that the rings were not solid, but made up of particles now known to consist of ice, dust and rock.

Saturn also has 53 known moons. They display a dizzying variety, from giant, cloud-shrouded Titan to the small, incredibly cratered Hyperion and ice-encrusted Enceladus, with its global ocean and geysers that spray water far into space.

Look for Saturn about 90 minutes after sunset in the southeast. It’s the bright light east of relatively luminous Mars, which moves west against the background of stars until the 29th. Just below and between the planets is Antares, the red heart of Scorpius. You may want to see all these objects in the first week of June, while Mars is still very bright and no moon interferes.

Jupiter is high in the southwest, below Leo, the lion. Between Jupiter and Mars shines Spica, the brightest star in Virgo, the maiden. Above Spica and Mars—high in the south—is Arcturus, the beacon of Bootes, the herdsman.

Looking north, the Big Dipper hangs upside down, while to the lower right the Little Dipper seems to stand upright on the tip of its handle: Polaris, the North Star. This is a good time to trace the form of Draco, the dragon, as it snakes from its head near the bright star Vega, in the east-northeast, then around the bowl of the Little Dipper to its tail between the dippers. A star chart will help.

On the 20th we get two notable events. A full moon, known to Algonquin Indians as the full strawberry moon, arrives at 6:02 a.m. However, in most locations it will have set by then; it’s best seen 4:30-5 a.m. or the evening before. The second event is the summer solstice, arriving at 5:34 p.m. At that moment the sun reaches a point directly over the Tropic of Cancer and summer officially begins.