Thebacha and Wood Buffalo Dark Sky Festival August 2017

This Week’s Sky: January 23 – 30

The Moon visits Saturn and Mercury in the morning sky.

Magnificent M42 by Martin Bernier

Martin Bernier captured this superb image of the Orion Nebula, M42, from his home in Saint-Liboire, Québec.

All Week

SW-45 minutes after sunset

The view facing southwest, 45-minutes after sunset.

Venus and Mars remain the story of the dusk sky, with the brilliant evening “star” far outshining its ruddy companion. At magnitude –4.7, Venus is easy to spot shortly after sunset. In bright twilight, it’s the lone point of light sitting roughly one third of the way up the southwestern sky. As darkness falls and a few stars begin to appear, 1.1-magnitude Mars pops into view less than six degrees above and to the left of Venus. The rest of the planetary action occurs after midnight. Jupiter leads the way—it rises slightly before midnight, then climbs to the meridian around 5:30 a.m., local time. The magnitude –2.1 beacon gleams a few degrees above 1st-magnitude Spica, in Virgo. Trailing far behind that pretty pair are the duo of Saturn and Mercury. The magnitude 0.5 ringed planet, which rises at 5 a.m., is slowly gaining altitude as winter progresses. By contrast, Mercury is wrapping up its first apparition of 2017. The elusive innermost planet shines at magnitude –0.2 low in the southeast as twilight begins.

January 24

ESE, 1-hr before sunrise

Facing south-southeast, one hour before sunrise.

Early rises will get to see the waning crescent Moon siting just three degrees from Saturn in the predawn sky. The pair will be a fine naked-eye sight and a treat in binoculars.

January 25

SE-1 hr before sunrise

Facing southeast, one hour before sunrise.

This morning an even thinner crescent Moon hangs above Mercury at dawn. You’ll need an unobstructed southeast horizon to catch the low-lying planet in brightening twilight. From Ontario, the Moon and Mercury will be roughly six degrees apart, but for observers on the West Coast the gap between the objects shrinks to less than five degrees by the time they rise.

January 27

New Moon occurs today at 7:07 p.m., EST.

Weekend Stargazer

Orion Sword

The Sword of Orion features several deep-sky tresures. The area shown in this image is roughly one binocular field wide. Photo by Gary Seronik, chart by Glenn LeDrew

The January 27 – 29 weekend is free from moonlight and ideal for winter deep-sky observing. One of the season’s undisputed treasures is the magnificent region known as the Sword of Orion. Here you’ll find a lovely open cluster, a fine double star and one of the most magnificent nebulas in the entire sky. All three targets can be appreciated with the smallest of telescopes, or even binoculars.

Over the years, pages and pages have been written about the Orion Nebula (also known as M42) in various observing guides and magazines. But to really appreciate this wonderful object, you have to see it for yourself. The Orion Nebula is bright enough to be visible even in light-polluted conditions, but under a dark sky it’s truly stunning. M42’s luminous core is pricked by four tightly-spaced glints known as the Trapezium, while ghostly, curving tendrils of nebulosity extend far outward. The larger the instrument, the more detail you’ll see, but to enjoy M42 in context, use binoculars or a low-power scope. Regardless of what optical aid you select, take your time with the Orion Nebula—the longer you look, the more you’ll see.

North of M42, at the top of the Sword, sits the open cluster NGC1981. It’s an attractive smattering of modestly bright stars occupying a patch of sky roughly half a degree in diameter. Binoculars and wide-angle “rich-field” telescopes show it best. Next, a little south of the Orion Nebula, is 2.8-magnitude iota (ι) Orionis. Iota is a binary star, but its tight, 7th-magnitude companion is difficult to detect in low-power optics. However, just 8 arc minutes south of iota, at the very bottom of the Sword, is a can’t-miss double called Struve 747. Featuring widely spaced 4.8- and 5.7-magnitude components, Struve 747 can be easily split in a small scope working at 20×. The pleasing Struve double and attractive NGC cluster are well worth inspecting—that is, if you can tear yourself away from the Orion Nebula.

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Categories: This Week's Sky
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