ou to star-hop to Comet Garradd in both the evening and morning sky. The Keystone of Hercules sets after the comet in the evening sky, yet rises before the comet in the morning sky. Find an unobstructed western horizon for evening viewing, or an unobstructed eastern horizon for the predawn showing.
How to find the Keystone in Hercules
To locate Hercules and the Keystone, it helps to know the brilliant star Vega. It’s the brightest of the three first-magnitude stars that make up the Summer Triangle asterism – which is much bigger than the Keystone! The Summer Triangle lights up the western sky on December evenings.
As darkness falls, look below or to the lower right of Vega to locate the Keystone in the western sky. (See chart below.) Or if you’re up before dawn, look eastward to find the Keystone asterism to the upper right of Vega. Whether you’re looking for this comet in the evening or morning sky, the four-sided figure of the Keystone serves as your faithful guide to Comet Garradd. Once you know the Keystone, branch out from there to fill out the stick figure of Hercules.
Comet Garradd in the evening sky
Our sky chart shows the stars in the west-northwest sky as they appear at roughly 7 p.m. local time in early December, or at dusk by the month’s end. We show the comet’s place for early December, in between the second-magnitude star Rasalhague, the brightest star in the constellation Ophiuchus, and the faint fifth-magnitude star Lambda Herculis of Hercules.
Identifying Lambda Herculis will greatly assist you in locating Comet Garradd in December. It’s a faint star yet visible to the unaided eye in a dark, moonless sky. If you can see Lambda Herculis, that increases your chances of catching the comet with binoculars. Comet Garradd moves toward the star Lambda Herculis throughout the month, and sweeps within a hairsbreadth of this star in late December.
Because the moon is waxing toward full during the first ten days of December, that makes the first third of the month a rough time for spotting Comet Garradd in the evening sky. By the time that the moon leaves the early evening sky around December 12, the comet will have sunk closer to the glare of evening dusk.
But don’t despair! Although the stars set in the western evening sky some four minutes earlier with each passing day, or one-half hour earlier with each passing week, these same stars also rise into the eastern morning sky four minutes earlier daily, or one-half hour earlier weekly. So the morning sky might be your better bet for seeing Comet Garradd in December.
Comet Garradd in the morning sky
Our sky chart shows the east-northeast sky for around 6 a.m in early December, or 4 a.m. by the month’s end. Brilliant Vega shines in the northeast sky, below the second-magnitude stars Rastaban and Eltanin, the two brightest in the constellation Draco the Dragon. Seek the comet about two fist-widths to the right of Vega and one fist-width below the Keystone. Hold your fist at an arm’s length away.
Moonlight will flood the predawn sky from about December 8 to 20. As fortune would have it, though, the last week of December presents the best chance to catch this elusive comet. At that time, there will be no moon to obscure the predawn sky. What’s more, Comet Garradd will rise earlier and climb higher into the morning darkness. Look for the comet to swing very close to the star Lambda Herculis for several days, centered on December 29. Aim your binoculars at this star … and who knows … you may see this faint fuzzball of a comet nearby.
By the way, the star Lambda Herculis and Comet Garradd will share the same binocular field of view from around mid-December till early January.
Star-hopping with binoculars to find the comet
Before looking for any comet, it’s best to practice star-hopping to deep-sky objects with binoculars. Since you’ll probably be using the Keystone to star-hop to Comet Garradd, how about star-hopping to the Hercules globular star cluster (Messier 13) right off the bat? Through binoculars, the Hercules cluster looks like a dim and possibly fuzzy star. With 