Do you have binoculars or a small telescope? And do you have access to a dark sky? If you’re up before sunrise in the coming days – say, from November 13 to 22, 2013 – you might be able to catch Comet ISON moving in front of the stars, as shown on the chart at the top of this post. The comet is in front of the constellation Virgo this week. Comet ISON is nowhere close to visibility with the unaided eye right now. But we’re hearing reports from many astronomers that it’s visible in binoculars, in a dark sky.
Refer first to the featured sky chart at the top of this post. It shows the big picture … Comet ISON moving on the sky’s dome from November 13 to 22. Remember, this is the predawn sky.
On the morning of November 13, you might spot Comet ISON near the rather faint (but visible) Virgo star Porrima.
As the days pass, Comet ISON is expected to grow some 2.5 times brighter before it meets up with Spica, the brightest star in Virgo. That’ll be on November 17 and 18. At that time, Spica and Comet ISON will easily fit into the same binocular field of view.
By November 22, when Comet ISON pairs up with the planet Mercury, the forecast calls for the comet to be about 6 times brighter than on November 13!
Now … how to get oriented under the stars? Look at the chart above. If you can find the Big Dipper – and you have the requisite binoculars and/or telescope, plus a dark sky – you can find these stars, and the comet on Wednesday, November 13.
First, extend the arc of the Big Dipper handle to locate the exceptionally brilliant star Arcturus. Then, continue to arc onward to Spica, the constellation Virgo‘s brightest star. Comet ISON will be moving toward Spica this week, on our sky’s dome. It’ll appear very close to Spica in the predawn/dawn sky on November 17 and 18.
Sure, all the latest forecasts predict a fainter Comet ISON than what had been hoped for at the time of the comet’s discovery in late 2012. The apparent magnitude of Comet ISON will be around 8.5 on November 13, and 7.5 on November 17. That means on November 13, the comet will be about 10 times fainter than the faintest star visible to the unaided eye. On November 17, it’ll be about 4 times fainter. So Comet ISON will not be easy pickings by any means.
Update: As of November 15, Comet ISON has brightened to an apparent magnitude of 6. That puts this comet at the threshold of naked-eye visibility. See: Comet ISON has an outburst!
Keep in mind that Comet ISON – though brightening – is also approaching the glare of sunrise throughout November. Time will tell whether Comet ISON will become bright enough to overcome the glow of dawn in the latter part of the month. Click here for a more comprehensive sky chart, courtesy of Comet Chasing.
Bottom line: On Wednesday, November 13, 2013, the Big Dipper can help you to locate Spica, your guide star to Comet ISON. The comet is not visible to the eye yet, but keep watching! Comet ISON will be in the same binoculars field with the bright star Spica in the predawn sky on November 17 and 18.