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The Sky This Week, 2012 February 7 - 14

Winter to Spring...
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Jupiter and Io, imaged with the USNO 12-inch refractor


The Moon wanes in the late evening and morning sky this week gliding through the rising springtime constellations, then diving southward on the ecliptic to join the first stars of the summer sky. Last Quarter occurs on the 14th at 12:04 pm Eastern Standard Time. On the evenings of the 7th and 8th look for Luna’s nearly full disc near the bright star Regulus in the constellation of Leo, the Lion. On the 9th her waning gibbous will rise some nine degrees south of the ruddy glow of Mars. On the 12th she is tucked within three degrees of the bright star Spica during the wee hours, and on the following morning she’ll be southeast of the golden glimmer of Saturn.

Despite the prognostications of the groundhog last week, the sky is inexorably edging toward spring. By 10:00 pm the heart of winter’s bright star patterns has drifted past the meridian, and late-night skywatchers can see the first of the next season’s stars rising in the east. There is still time to enjoy Orion and the rest of his bright cohorts during the early evening hours, but as the time of sunset creeps later by a minute each day the stars of the Winter Circle are gradually losing time in a fully darkened sky. By the end of the week you’ll have one more opportunity to count the stars within Orion’s bold outline for the February session of the Great World-wide Star Count project of The Globe At Night citizen science program. This month’s activities begin on the 12th and run through the 21st. By the time the March "window" opens we’ll have to shift our attention from Orion to the stars of Leo.

The bright planet Venus is now mounting a serious challenge to Jupiter for your attention in the evening sky. Venus is rapidly closing the gap between the two planets, shaving almost a degree per night as she continues to rapidly climb into the evening sky. The motions of Venus are quite complicated to understand from an Earth-based point of view. The planet makes five evening apparitions every eight years, with the most favorable apparitions occurring at roughly eight year intervals. This is one of those very favorable years for those of us in the northern hemisphere, and we’ll get to enjoy the planet’s dazzling show through the late spring.

While Jupiter must give up some of the limelight to Venus, he’s not quite done with his current evening show yet. The giant planet is still well-placed in the early evening sky for owners of small telescopes, and you still have a few more weeks to enjoy the antics of his bright Galilean moons and the swirling detail in his roiling clouds. You can spot Jupiter almost immediately after sunset, and as the evening twilight deepens you can begin your exploration. By 10:00 pm, though, he has descended into the haze and turbulence above the western horizon and probably won’t show more than a cream-colored featureless disc and four bright blobs in the eyepiece.

Mars is on the threshold of his opposition appearance for the year. He rises at around 8:00 pm at the beginning of the week and comes up about five minutes earlier with each successive night. He is located underneath the triangle of stars that form the "haunches" of Leo the Lion, and you’ll have no trouble picking him out in the eastern sky by 9:00 pm. While his apparent disc is about a third the size of Jupiter’s, his pink surface offers a striking contrast to the beige hues of the giant planet. His north polar ice cap stands out with a dazzling white against the rusty hue of his trackless deserts, and when the air is very steady you can pick out some of his dark surface markings.

Saturn rises at around 11:00 pm this week, and late-night skywatchers can now catch a glimpse of him and his magnificent rings before turning in for the night. He is close to the bright blue star Spica in the constellation Virgo, and this week receives a visit from the Moon on the early mornings of the 12th and 13th.

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