Weekend Stargazer: June 23 – 25

Saturn and its five brightest moons as they appear at 1 a.m., EDT, Saturday morning.
Saturn and its five brightest moons as they appear at 1 a.m., EDT, Saturday morning.

Short nights over the weekend don’t lend themselves to in-depth deep-sky observing, so why not give in to temptation and have a look at Saturn? The ringed planet was at opposition on June 15, and is visible all night long.

What does Saturn offer telescope users? Rings, obviously—that’s what Saturn is famous for. And this year is a particularly good time to view them. Saturn’s north pole is tilted nearly 27 degrees Earthward, which means the rings are fully open and at their best. But don’t neglect the planet’s brightest moons. Although most telescope user make a point of following the comings and goings of Jupiter’s four Galilean satellites, I’m struck by how rarely those same observers deliberately view Saturn’s moons.

Titan is the one you’re most likely to spot first. It shines gamely at magnitude 8.4, and is usually the brightest point of light near the planet. But if you have an 8-inch scope, you could see as many as four additional satellites, including Rhea (magnitude 9.7), Tethys (10.3), Dione (10.4) and Enceladus (11.8). You can find their current positions in the RASC’s Observer’s Handbook or with this handy on-line calculator.

Saturn is second only to Jupiter when it comes to hoarding moons. At last count, Saturn lays claim to a mind-boggling 62 satellites ranging in size from 5,149 kilometres (Titan) down to jagged moonlets smaller than Mount Everest. Unfortunately, apart from the five already mentioned, this bountiful harvest of satellites lies beyond the reach of backyard telescopes.