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Heavenly Skies: Saturn to make entrance, reach peak visibility April 28

By: By Forrest Lockhart, Special to Gold Country News Service
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The recent winter sky has been dominated by the solar system’s largest planet, Jupiter. This spring, the giant planet is slowly moving toward the western horizon on its 12-and-a-half-year trip around the Sun. As Jupiter slips westward, another major planet stands ready to take center stage — Saturn.

As twilight ends, what is arguably the most spectacular astronomical object in our solar system will rise over the eastern horizon. About 30 minutes after nightfall, sky gazers who cast their eyes to the east will spy the bright, unblinking, cream-colored point of light — Saturn.

The most distant of the five naked-eye planets known to the ancients, Saturn is also the second largest planet in our solar system. Saturn’s incredible ring system surrounding the planet draws admiring comments from all who have access to telescopes. On April 28, Saturn will reach peak visibility as it and Earth come within 830 million miles of each other, closer than at any other time this year.

Due to its size of about 75,000 miles in diameter, almost 9.5 times that of Earth, observers don’t require a large telescope to be entranced with the view. In fact, even binoculars of medium magnification will provide an inkling of the magnificence of the planet. But to truly enjoy the planet and its awesome rings, a telescope of modest aperture is advised.

Through a telescope eyepiece there are a myriad of features to discover. In recent months, astronomers frequently note the presence of bright transient storms in Saturn’s upper atmosphere. Due to the rapid rotation of Saturn, these pale storms race around the planet in little more than 10 hours, allowing an opportunity to glimpse a storm on clear evenings.

Saturn has the only complete set of rings in the solar system. The probable product of a shattered moon crushed by Saturn’s immense gravity, the rings extend from just a few thousands of miles above the cloud tops to a total width of about 150,000 miles, yet the average thickness is only about 3,000 feet. The rings are thought to consist of countless small water-ice particles, ranging in size from small pebbles to chunks the size of a building. Even telescopes of modest size reveal a dark gap between the two brightest ring structures. This gap, named the Cassini Division for its discoverer, Giovanni Cassini, is thought to result from gravitational effects of nearby moons.

While Saturn boasts a retinue of over 60 moons, the star of the show is Titan, the second largest moon in the solar system. Orbiting Saturn once every 16 days, observers can track Titan nightly as it seems to swing back and forth across the planet like a pendulum.

Admission is free to the Cameron Park Rotary Community Observatory in Placerville. For information, visit communityobservatory.com.