The ringed world dominates the night

Saturn reaches its 2015 peak May 22 and is a stunning sight for the next few months.
By and | Published: May 12, 2015
Saturn on April 1, 2015
Saturn’s wide-open rings in 2015 create a stunning sight for observers using any size telescope.
Christopher Go
Saturn puts on an impressive show during the warm nights of late spring and early summer. It reaches opposition and peak visibility May 22, when it lies opposite the Sun in our sky and remains visible all night. The planet then climbs higher in the evening sky during June, when observers with telescopes will get exceptional views of the planet’s beautiful ring system.

Saturn spends 2015 among the background stars of northern Scorpius and eastern Libra. During April, when the ringed planet rose shortly before midnight, it made the Scorpion’s pincers look like they’d gained a talon. Saturn passed 1° north of Beta (β) Scorpii in early May, and now its westward motion carries it into Libra.

Saturn comes to peak visibility May 22, when it shines brightly in the south-eastern sky after darkness falls.
Saturn comes to peak visibility May 22, when it shines brightly in the southeastern sky after darkness falls.
Astronomy: Roen Kelly
At opposition, the gas giant world shines at magnitude 0.0, a full magnitude brighter than Scorpius’ brightest star, Antares. Yet Saturn’s great distance from Earth means its appearance changes slowly — it doesn’t fade below magnitude 0.2 until July.

The planet also remains visible all night at opposition. Unfortunately, it then reaches its maximum altitude (about 30° from mid-northern latitudes) around 1 a.m. local daylight time. June and July offer superior evening views. It stands highest in the south at 11:30 p.m. in mid-June and at 9:30 p.m. a month later.

If you’ve never seen Saturn through a telescope, 2015 is a great year to start. The rings tilt 24° to our line of sight this summer, just 3° less than their maximum possible. This affords great views of ring structure. The Cassini Division that separates the outer A ring from the brighter B ring stands out through any scope.

The ringed planet appears near the border between northern Scorpius and eastern Libra at its best this year. Saturn peaks at magnitude 0.0 and shine noticeably brighter than any of these constellations’ stars.
Astronomy: Roen Kelly
The rings span 42″ at opposition, and they make up for the planet’s bland globe, which measures 19″ across. Through even the smallest telescope, you can even spot Saturn’s largest moon, Titan, which shines at 8th magnitude. You’ll find it due south of the planet May 26/27. Slightly largest instruments will reveal three additional moons orbiting inside Titan, 10th-magnitude Tethys, Dione, and Rhea. The final bright moon is distant Iapetus, which glows at 10th magnitude when it reaches greatest western elongation May 19/20. It then stands 9′ from Saturn, a far greater distance than any of the other moons.

If you don’t own a telescope, find a friend who does or contact your local astronomy club for observing nights. Saturn is a sight you won’t soon forget.

Fast facts

  • Saturn is the second-largest planet in the solar system, and more than 750 Earths could fit inside it.
  • Saturn is the only planet in our solar system that’s less dense than water, and it weighs only 95 times as much as Earth. As such, the planet would float in water.
  • It takes Saturn about 29 years to orbit the Sun but a little less than 11 hours to rotate completely.
  • Saturn’s quick rotation flattens it slightly, so its polar diameter is only 89 percent of its equatorial diameter.
  • Saturn’s rings can be as thin as 33 feet (10 meters) thick and are made almost entirely of ice.
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