The fall weather may be appealing, but the gloomy skies the past couple of days haven’t really helped anyone looking up for Comet Hartley 2, which made it’s closest pass yesterday. It’s still pretty darn close (just 11 million miles away!), so if the skies clear up you can find the icy comet to the left of Taurus in the constellation Auriga, starting a little after 10 p.m. Meanwhile, NASA’s Deep Impact probe, on its EPOXI mission we discussed last week, ventures closer to Hartley every day, preparing for its fly-by on November 4.

October greets us with a fun astronomical event: Comet Hartley 2 will be at its most visible with just a little help all month, and visible but steadily fading from view through the end of 2010. Sky & Telescope has all the comet info you need, including that it was discovered in 1986 and will make its closest known approach to Earth this year, passing at just 0.12 AU (an AU is a commonly used unit of distance that stands for ‘astronomical unit’ and equals the distance between the sun and the Earth, almost 93 million miles, so 0.12 AU is about 11 million miles). If you’re away from the city lights, you may be able to see Hartley 2 as it reaches 5th or 6th magnitude on October 20 with your naked eyes; for the rest of us, a simple pair of binoculars should do the trick just fine. (Here’s Hartley 2 being chased by Pac-Man on NASA’s Astronomy Photo of the Day.)