You are here: Home USNO News, Tours & Events Sky This Week The Sky This Week, 2014 January 14 - 21

The Sky This Week, 2014 January 14 - 21

Poking around Orion's Sword

Messier 42, the Great Nebula in Orion

Imaged 2014 January 1 from Morattico, Virginia
80mm (3.1-inch) f/6 Antares Sentinel refractor,
iOptron "Cube Pro" portable go-to mount,
Canon EOS Rebel T2i DSLR

30 x 30-second subframes @ ISO 6400

The Full Moon beams down from high among the stars of the Great Winter Circle as the week opens, then wanes to a gibbous phase as she dives toward the southerly reaches of the Ecliptic. Full Moon falls on the 15th at 11:52 pm Eastern Standard Time. It happens to occur within three hours of one of the year’s most extreme lunar apogees, the time when Luna is most distant from the Earth. Much ado has been made in the past several years about "Supermoons", Full Moons that occur at a time of extreme lunar perigee; this is the opposite case. Perhaps we should call it the "anti-Supermoon"? Luna passes just five degrees to the south of bright Jupiter on the evening of the 14th. On the 18th she is a similar distance to the south of the bright star Regulus. She ends the week by homing in on the planet Mars and the bright star Spica in the pre-dawn sky.

As with much of last week, light from the waning Moon will wash out all but the brightest stars for most of this one as well. If you didn’t get a chance to wend your way around the multi-colored stars of the Great Winter Circle yet you still have that chance to spot them in a bright but relatively uncluttered sky. However, by the end of the week we’ll begin to get a couple of hours of astronomical darkness to look for some of the more subtle showpieces of the winter sky. One of these is located in a tight little asterism that lies just below the famous "Belt Stars" of Orion. Even on a moonlit night under urban skies you should be able to spot the three vertically aligned stars that make up the group known as "The Sword", and as the sky darkens you might notice that the middle one appears "fuzzy". A glance at this fuzzy star with binoculars will reveal its true nature as a small group of blue-tinted stars surrounded by a softly-glowing cloud of gas. This is the famous Great Nebula in Orion, which is probably the easiest "deep-sky object" to observe in the entire sky. Larger telescopes and darker skies reveal ever-increasing amounts of detail in the swirling clouds of bright and dark material that make up this object. Most of us suburban stargazers can see the bright central part of the nebula that surrounds a small tight group of four blue stars known as the Trapezium. This gas glows with the characteristic light of doubly-ionized oxygen, stimulated by the intense ultraviolet light from the Trapezium stars themselves. These stars are among the youngest and most energetic stars known in the Galaxy, and the nebula is the brightest part of a huge complex structure that is forming many more such energetic suns. Under progressively darker skies darker clouds of cooler gas and dust reflect the blue light of the central stars, framing the brighter core. In telescopes of six or more inches in aperture the nebula takes on a near "3-D" aspect, filling the eyepiece field with swirling knots and eddies of texture. In my 14-inch telescope from the skies of rural Virginia the central region begins to show a faint greenish tint framing the intense blue blaze of the Trapezium and its neighbor stars. My favorite view, though, is the low-power one I have through my modest 3-inch refractor. This places the nebula in the context of the other stars in the "sword", each of which resolve into clumps of icy blue-hued luminaries. Although its visual appearance hasn’t changed much since it was first seen in a telescope 400 years ago, the Great Nebula is one of the few objects of its type that appears "dynamic"; I can only imagine the colossal forces of nature that are at work in its glowing heart.

Closer to home we find the bright Moon hanging near Jupiter as the week opens, but you won’t need the Moon around to identify Old Jove on any given night. Jupiter shines down from high among the stars of Gemini and, with the current absence of Venus from the sky, is the brightest object in the heavens after the Sun and Moon. Jupiter is a treat to look at with almost any form of optical aid; even a pair of binoculars will give you a good view of the planet and the four bright moons discovered by Galileo in January of 1610. A particularly good night to do this will be that of the 16th, when all four moons will be well-separated from the planet’s disc. As a bonus on that night, if you have a four-inch or larger scope, the famous Great Red Spot will rotate across the center of the planet at around 8:30 pm.

If you’re up past midnight you can begin to look for Mars rising in the southeastern sky, but the best time to see the red planet is still in the hours before dawn. He’s steadily growing brighter and more prominent in the sky, now only exceeded in brightness by the nearby star Arcturus. His disc is still fairly small for the modest telescope, but steady air in the pre-dawn sky may allow you to see some details, especially his bright north polar ice cap. Mars is located about six degrees northwest of the bright star Spica by the end of the week. He’ll be spending most of next few months near the star.

Saturn is also available for your perusal before sunrise, located in the obscure constellation of Libra, the Scales. Saturn’s rings are now tipped generously in our direction, which makes up somewhat for his southerly declination. Detail is harder to eke out when we have to look through more of Earth’s atmosphere, but the planet’s unusual appearance should nonetheless be easy to make out with a minimum of optical aid.

USNO Master Clock Time
Javascript must be Enabled