August 2022
The Backyard Astronomer
Adam England

The Ringed Planet

Excerpt from Systema Saturnium, Christiaan Huygens, 1659

The planet Saturn has intrigued astronomers, both professional and amateur, since Galileo first sketched what he thought were two odd-shaped moons on either side of the planet. His final telescope at 30x magnification was still not quite able to resolve the rings we love so much to gaze on. Dutch mathematician Christiaan Huygens explained the rings of Saturn by 1659 and identified its moon Titan with a slightly larger telescope at 43x magnification. Both were major accomplishments for their time, and now even the most basic telescopes and binoculars can show us the beautiful rings and Titan nearly any time of year.

With a volume 763 times that of Earth, Saturn is the second-largest of our system’s gas giants, behind Jupiter. Despite its huge size, its average density is less than that of water, so it’s only 95 times the mass of Earth.

In August the planets align to give the best view of the year, an exceptional viewing opportunity. Saturn reaches opposition on August 14, when it is the closest to us and at its brightest, its earthward side fully illuminated by the sun. It will be one of the brightest objects in the sky this month, moving westward along the ecliptic, the path that all planets take across our southern sky. On that night you’ll find it near the tail of the constellation Capricornus.

Positions of Saturn's visible moons on August 14

At that point it will be about 816 million miles away, a distance that takes light 73 minutes to traverse. So when you’re gazing at the Ringed Planet, you are actually seeing light that left the Sun, traveled for an hour and 21 minutes to Saturn, then back an hour and 13 minutes to your eyepiece in Northern Arizona. Those same photons may have taken upward of a million years to escape the 430,000 miles of the Sun’s dense plasma, but we’ll have to discuss that in more detail on another day.

If your telescope mirror is two inches or larger in diameter, you should also be able to see Titan off to the side, with the rings nearly making a line pointing to that moon, which is larger than Mercury. Titan’s dense methane atmosphere is often tinged with orange.

The new James Webb Space Telescope will be photographing the outward planets, starting with the orbit of Mars, over the next few months and years, and the results will be sure to amaze. In the meantime, if you are able to get a picture of Saturn through your telescope, share it with us on social media!

If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.

Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.