What’s Up for September 2006

Many apologies for being about a week late on this article. Hard to believe that a week of September has already passed us by…

What’s New

September begins the prime stargazing season for most northern hemisphere observers. The equinox occurs later this month, after which the nights will be longer than the days (finally!). The weather patterns calm down, the atmosphere steadies, and here in the States, the air starts coming down from Canada, rather than from the tropical Gulf. The dry, steady air brings a tranquility to the season that is perfect for stargazing.

On the 15th, the Moon will be at its highest in the sky in over a century for those in the northern hemisphere. (For those in the southern hemisphere, the Moon will be unusually low in the sky.) Here’s an article by J.E. Brown that does an excellent job of explaining why. Don’t look for it after sunset - it will be visible in the early morning sky.

There’s a lack of notable activity going on in the solar system this month. Jupiter continues to dominate the evening sky after sunset. If you are awake before dawn, you’ll have a chance to see a blazing Venus sinking into the glare of sunrise each day. Saturn has become an early morning object, and is preparing itself for another great wintertime apparition.

But the story continues to be the late summer’s Milky Way, hissing like a puff of steam from the teapot-shaped constellation Sagittarius. There’s nothing quite like taking a pair of binoculars (or a wide-field, low-power telescope), aiming at the teapot’s “spout,� and slowly moving upwards. Billions of stars are visible even in modest-sized binoculars, spread across the field like a fine ash. Here and there, some of the ash clumps into star clusters; and occasionally a dark nebula creates a river of blackness through the field.

What’s Old

There are only nine Messier objects near the meridian around local midnight this month. One of these, M-73 (pictured left), is a grouping of four Y-shaped stars in Aquarius. Cygnus features the two open clusters M-39 and M-29. Both are rather loose and veiled within the billowing star clouds of the Milky Way. M-39 is close—only 825 light years (ly) distant—and spans a large area of sky, almost as much as the Moon. M-29 is much, much farther at 4000 ly, with a diameter of a mere 7 arcminutes.

M15... click to embiggenateFour-thousand light years seems fairly distant until you point a scope on the remaining M-objects, which are all globular clusters. The closest of the group is M-30 in Capricorn, shining at a distance of 41,000 ly. Next is the very famous M-15 (pictured right) in Pegasus, which is 49,500 ly away. As we reach 55,000 ly, we pass M-2 in Aquarius. Staying in that same constellation, there is M-72, and its remoteness of 62,000 ly makes it intrinsically dimmer. The record holder for these remaining few globulars, however, is M-75 in southern Sagittarius. The light from the stars within this cluster left a whopping 78,000 years ago!

Other deep sky objects to hunt for are the planetary nebulae NGC-7026, 7027, and 7008 in Cygnus, and the Saturn Nebula in Aquarius.

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