Saturn And The Strawberry Moon Have A Double Opposition

Saturn in all its ringed and banded glory photographed on June 24, 2018. The dark gap called Cassini’s Division separates the outer A ring from the broad and brighter B ring. A fainter C ring (partially silhouetted against the planet) is also visible. Christopher Go

Skywatchers always look forward to oppositions. That’s when an outer planet lines up on the same side of the sun as the Earth, and the two are closest together for the year. For Saturn that day is Wednesday, June 27. The ringed planet will rise about sunset and shine all night long. Dropping by to celebrate the special day, the Full Strawberry Moon hovers just 1° above the planet. Since both the full moon and Saturn rise opposite the sun, they’re both at opposition — an unusual occurrence!

Saturn and the Strawberry Full Moon get together Thursday evening. Click the photo to find the time the moon rises for your city. Stellarium

Saturn will shine at magnitude 0.0 or as bright as Vega in the Summer Triangle and will be plenty bright to hold its own next to the full moon. A pair of 10x binoculars will show the planet as elongated or “out of round” because the rings extend beyond Saturn’s spherical globe. In truth, Saturn’s not quite spherical. Like Jupiter, it’s outer layers are all gas, and both planets spin so rapidly — a day on each is about 10 hours — that they flatten into ovals.

The maximum tilt Saturn’s rings can have is 27°. This season, they’re very close to that, currently 26° with the north side of the rings open in our direction. Because Saturn’s axis is tilted 26.7° we see alternate ring faces (north and south) during the course of its 29-year run around the sun. These times coincide with summer and winter at Saturn.

Saturn’s tilted axis means we get to see an ever changing presentation of its rings as the planet revolves around the sun in a 29.5 year orbit. On opposition day, Saturn will be 841 million miles from Earth. That’s more than 150 million miles closer than it will be when it’s on the opposite side of the sun from us come winter. Credit and copyright: thChieh

At Saturn’s equinoxes, we see the rings edge-on when they practically disappear from view because they’re only about 30 feet (10 meters) thick. Compared to their diameter of 185,000 miles (300,000 km) the rings are as thin as the plastic wrap you drape over that slice of pizza in the microwave.

Saturn’s rings brighten up for a couple days around opposition because we’re looking at the planet with the sun at our backs. The ice particles that make up the rings are fully illuminated (just like the full moon) with their shadows hidden behind them. Without shadowing, the rings get a boost in brightness. You can see the change (it’s called the Seeliger Effect) in a telescope if you look at Saturn now and check it again a few weeks past opposition.

Saturn viewed through a small to medium telescope on opposition night, June 27. Titan and Rhea are the brightest moons and look just like stars. North is up. Stellarium

Even though Saturn rises around sunset now, it takes the planet a little time to climb high enough to clear the trees and buildings. If you go out at 10 or later and face southeast, you shouldn’t have any problem spotting it. Saturn is the only bright star low in the south at that time. Mars, the next bright planet in line, doesn’t come into good view till midnight, and it’s much brighter and fire-colored.

Saturn shows its rings in even a small 60mm (2.4-inch) telescope using magnifications of 30x and higher. In smaller scopes the rings blend into a single, broad ring, but if you have a 6-inch or larger telescope, up to three rings are visible. The brightest, Ring A and Ring B, are separated by a dark gap called Cassini’s Division, visible when the air is steady and the planet appears sharp and clear at higher magnifications.

Depending on the size of your telescope you’ll see from one to several “stars” very near the planet. These are a few of the largest of its 62 known moons. Brightest is Titan which you can see in even the smallest telescope. Use the free program Stellarium, available for PC and Mac, to see the positions of the moons at any time of day from any place. Or you can use Sky & Telescopes Saturn Moon finder.

Saturn also has belts like Jupiter but outside of the equatorial ones, they’re pretty low contrast. If the image is sharp in your scope, look for the dark stripe of the north equatorial belt.

Happy ring-gazing!



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