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Tuesday, September 28, 2010

In late September 2010, time to search for Comet Hartley 2 with binoculars

You might be able to see Comet Hartley 2 with binoculars by late September 2010. You might see it with the eye alone in October 2010. To find it, first learn the constellation Cassiopeia.

Comet Hartley 2 – possibly 2010’s brightest comet – might become bright enough to see with binoculars by late September. It could possibly become faintly visible to the unaided eye in October.

To find the comet, first find the constellation Cassiopeia the Queen. This constellation is easy to spot in the northeast in the evening now. Cassiopeia is shaped like the letter M or W. This comet will sweep next to Cassiopeia in late September and early October 2010.

Just remember … Cassiopeia always appears in the northeastern sky at nightfall on September and October evenings. It swings low in the northern sky in the wee hours after midnight in September and October. Then, as night progresses toward dawn, you’ll find Cassiopeia in the northwestern sky before dawn. Just look in the locations mentioned above for a W or M-shaped star pattern.

What will the comet look like?

Comets are surprising objects in many ways. After all, they are loosely bound balls of ices from the outer solar system. Sometimes, comets appear without warning. Comet Hartley 2 has been expected for many years, however. Officially designated 103P/Hartley, it is a periodic comet, which returns again and again near our sun and Earth. Its orbital period is thought to be 6.46 years. Even so, the brightness and appearance of this comet – or any comet – never follows an ironclad forecast. Don’t be surprised if Comet Hartley 2 exceeds or falls shy of expectation.

You will need a dark sky – free of city lights or moonlight – to see this comet. Through your binoculars in late September and October, it should look like a smudge of light against the dark sky background. Comet Hartley 2 may look like a faint, fuzzy star. Or it may exhibit a discernable tail. Only time will tell.

The element of suspense always accompanies the return of a comet to Earth’s sky. That’s one reason they are fun to see!

How to find Comet Hartley 2 with binoculars

A typical binocular field covers about 5 degrees of sky. Sometimes the field of view (F.O.V.) is listed right on your binoculars. For handy reference, the distance between the Cassiopeia stars Caph and Schedar measures about 5 degrees. Remember this, as it will serve you well on your hunt for Comet Hartley 2.

Around the night of September 30, look for Comet Hartley 2 near the star Schedar (Alpha Cassiopeiae). It passes within 1.5 degrees of this star on September 30. That means Schedar and the comet will fit within the same binocular field together for several days in a row, centered on September 30.

Around the night of October 7, look for Comet Hartley 2 near the very beautiful Double Cluster in Perseus. (Think photo opportunity!) The comet will travel within one degree of this famous cluster on October 7, but you should also look for Comet Hartley in the cluster’s vicinity on the nights of October 6, 8 and 9. It’s fun to mentally note how the comet changes position relative to the background stars from night to night. How can you find the Double Cluster? Star-hop to it by drawing an imaginary line downward through the stars Navi (Gamma Cassiopeiae) and Ruchbah (Delta Cassiopeiae). Even in moderately light-polluted skies, the Double Cluster is fairly easy to make out with binoculars. It’s faintly visible to the unaided eye on a dark, moonless night.

After October 10, finding the comet gets tricky, because the moon will be returning to the evening sky. The moon’s glare will make the comet harder to see. It will probably be best to observe Comet Hartley 2 after moonset from October 11 to October 20.

Deep Impact spacecraft also headed to Comet Hartley 2. By the way, the Deep Impact spacecraft – which was launched by NASA in 2005 and successfully sent a collider into Comet 9P/Tempel – had its orbit around the sun tweaked in May of 2010 with the goal of sending it close to Comet Hartley 2. This mission has now been re-designated EPOXI. The craft will pass most closely to the comet in early November, 2010. Mission overseers are provided status updates for EPOXI’s impending sweep past Hartley 2.

All in all, it will be an interesting autumn season for comets, thanks to Comet Hartley 2. Be sure to make friends with Cassiopeia, your tour guide to the comet. The trick to comet hunting is to know right where to look for its place in the starry sky, and Cassiopeia will help. If all goes well, Comet Hartley 2 will become a binocular object in late September and reach naked-eye visibility in October.

For more information, bookings for public observing evenings with large telescopes at the observatory, and repairs and servicing to all your optical equipment, contact Mike at SkyOptic, phone 331478 or email

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