With Comet 168P/ Hergenrother still bright and perfectly placed high in the southeast at nightfall, I wanted to share an updated map for amateur astronomers with 6-inch and larger telescopes who’d like to track the comet. At around magnitude 9.5, it’s still the brightest fuzzball in the fall sky. For the next couple weeks, 168P will track from northern Pegasus into Andromeda as it slowly fades. Put it on your list of autumn night sky targets and you won’t be disappointed.
If you don’t see the comet this time around, you’ll have to wait 7 years for its return. Hergenrother is a short period or periodic comet – one that orbits the sun in fewer than 200 years. That’s what the “P” stands for in its name. Since its discovery in 1998 by American astronomer Carl Hergenrother, this feathery visitor is making its third observed trip. About 265 numbered periodic comets have been discovered to date. Unnumbered periodic comets number nearly 250.
Next in our comet lineup is comet C/2011 L4 PANSTARRS. The “C” indicates a long-period comet or one that orbits the sun in more than 200 years. Two hundred? That’s nothing. L4 Pan-STARRS’s period is estimated at 110,000 years. Seeing it’s a once-in-a-lifetime experience for sure.
Right now, the comet looks like a small, dense cotton wad of light in southern Libra visible only from the southern hemisphere low in the west during early evening hours.
Pan-STARRS has plateaued at a dim 11.5 magnitude for the past few weeks, but is expected to slowly brighten through fall and winter. Northern hemisphere observers will have to be patient. We won’t spy it till next March because the comet will either be too near the sun or too low in the sky.
On March 9, 2013 , L4 PANSTARRS passes just 28 million miles from the sun. In the days before and after, solar heating will furiously vaporize ice and dust from its outer crust causing the comet to quickly brighten and develop a substantial tail. A few days later it pops into the evening sky and could shine as bright as -1 magnitude or nearly the equal of Sirius, the brightest star. That’s what the predictions say anyway. More information and a sky chart HERE.
At least we can see L4 Pan-STARRS with an 8-inch or larger telescope. Comet C/2012 S1 ISON at 17th magnitude dips way below the limit, though amateur astronomers using larger instruments and digital cameras have taken pictures of it. ISON was scooped up by Russian amateur astronomers Vitaly Nevski and Artyom Novichonok in the course of the work for the International Scientific Optical Network (ISON) Survey from near Kislovodsk, Russia on Sept. 21. I hope the two are eventually recognized for their discovery by having their names penned to the comet instead of a survey acronym. Other comets discovered during surveys have received the discoverer’s name. Why not this one?
S1 ISON creeps very slowly across the constellation Cancer in the morning sky this month and next and won’t become visible in typical telescopes until next September. On November 28, 2013, the comet passes just 800,000 miles from the sun. If it survives the encounter, it could become brighter than Venus and be visible in broad daylight. A few days after its near-death experience, ISON swiftly moves northward, becoming visible in both evening and morning skies.
Ernesto Guido and the team of amateur astronomers at the Remanzacco Observatory in Italy have observed a large amount of activity in the comet’s nucleus this fall despite it being 558 million miles from the sun or farther than Jupiter. Mike Mattei, another amateur astronomer, reports that Earth will pass under the incoming leg of ISON’s orbit. If the comet is large and active, he predicts we could see an increase in meteor activity around January 14-15, 2014 spawned by dust cooked off the comet nucleus. Isonids anyone?
Though I’ve heard it’s possible ISON could rival the full moon’s brightness and become one of history’s “Great Comets” when it appears in both morning and evening skies in early December, I’m going to play the conservative card. I’ve been burned by a few comets that haven’t lived up to expectations, and besides, these creatures are unpredictable anyway. That’s their charm. It could easily be fainter or brighter, though the latter is preferable by far. More on the S1 ISON including sky charts HERE.