We in the Northern Hemisphere can’t see Comet Lovejoy, which is now gracing Southern Hemisphere skies. But, if you’re up for a challenge, grab your binoculars and head for a clear, dark sky to see Comet C/2009 P1 Garradd. It’s the northern sky’s most conspicuous comet now, approaching sixth magnitude in brightness. It’s visible through binoculars, even though the comet is quite faint. Your best bet for catching this comet will probably come in the last week of December, as Comet Garradd pairs up with the visible star Lambda Herculis in a moonless, predawn sky.
The last time I looked, Comet Garradd looked like a ghost of a fuzzball in my 10×50 binoculars, with no hint of a tail. All the same, it’s a great thrill to catch this creature of the wild roaming in the wilderness of the solar system.
This comet is predicted to remain at about the same brightness until March 2012. The magnitude isn’t expected to change greatly over the next several months, though Comet Garradd will probably peak in brightness in February 2012.
And there’s more good news. Until now, Comet Garradd has been traveling relatively rapidly across our sky, passing many constellations along the way, making it a hard target to track for casual viewers. Now, though, the comet has settled into a region of the sky near a noticeable star pattern, or asterism – the famous Keystone asterism of the constellation Hercules. Comet Garradd will be in front of Hercules from now until February 2012. So finding Hercules – and its Keystone star pattern – is your ticket to seeing Comet Garradd.
Ready? Let’s chase a comet!
Comet Garradd transitions from evening to morning sky in December
This month, the search for Comet Garradd is somewhat complicated by the fact that it transitions from the evening to morning sky in December 2011. At mid-northern latitudes in early December, the comet sits low in west at nightfall, sets beneath the horizon by early evening, and rises over the eastern horizon before dawn.
The constellation Hercules and its Keystone asterism enable you 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 