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The Sky This Week, 2014 December 9 - 16

How many stars can you see in Perseus?
NGC7789_130815_01small.jpg
NGC 7789, "Caroline's Rose" star cluster in Cassiopeia
This is one of the many galactic star clusters that may be found in the
Milky Way between Cassiopeia, Perseus, and Auriga.
It was discovered by Caroline Herschel, sister of astronomer William Herschel, in 1783.

The Moon glides into the morning sky this week, wending her way through the rising stars of the springtime sky.  Last Quarter occurs on the 14th at 7:51 am Eastern Standard Time.  Luna rises near bright Jupiter late on the evenings of the 10th and 11th.  You’ll find her waning crescent near the bright star Spica before sunrise on the morning of the 16th.  

Those of us who keep track of these things will be heartened to know that by the end of the week we will start to see evening sunset times gradually edging later.  This is an aspect of several phenomena that occur around the time of the winter solstice.  Most of us probably won’t notice the change until around Christmas, and by the end of the year Old Sol will be setting a full 10 minutes later than he does right now.

The final monthly observing campaign for the citizen-science program “Globe at Night” begins on the 11th and runs through the 20th.  So far this year over 18,000 observers have contributed star visibility reports to help chart the degradation of the night sky due to the effects of light pollution.   The premise is incredibly simple: find a familiar constellation on a moonless night and compare the number of stars you see with the naked eye to a visibility chart on the program’s Web site.  Astronomers will use these data to chart out the locations of major sources of artificial lighting that is obscuring more and more of the night sky.  The intention is to make people more aware of the disappearance of the night sky as a natural resource and to engage the public in reducing this wasteful use of energy resources.  It is now a well-established fact that artificial nighttime lighting disrupts the migratory senses of many animal species as well as our own circadian rhythms, and there is growing evidence that it may pose many other long-term health effects in humans.  Fortunately this is an energy problem which is quite easily solved with a bit of public awareness.  You can do your part by simply going out on a moonless night and looking up.  This month the constellation of Perseus, the Hero is our star-counting focus.  You can find Perseus high in the northeast at 7:00 pm, between the “W”-shaped asterism of Cassiopeia and the bright golden star Capella.  If you’re away from the lights of the city, explore this part of the sky with binoculars.  You’ll be rewarded with a view of many star clusters interspersed among the star-clouds of the Milky Way.

By now you should be able to easily locate dazzling Venus in the southwestern sky as evening twilight deepens.  By the end of the week she sets 50 minutes after the Sun, and as we approach the year’s end she will set 2 minutes later on each successive night.  

Ruddy Mars continues to keep ahead of the Sun, setting at the same time, 8:13 pm each night through the end of the year.  The red planet is now transiting the dim autumnal constellation of Capricornus, the Sea-Goat, and will be the brightest object in this part of the sky after Venus sets.  His reddish tint should help distinguish him from the more southerly beacon of the bright star Fomalhaut.

Bright Jupiter now rises at around 9:30 pm and is progressing steadily toward being the dominant object in the evening sky.  Old Jove rises with the waning gibbous Moon in the late evening of the 11th.  Early risers can get a great view of him just west of the meridian at 5:00 am, and pre-sunrise times are still the best for catching a good glimpse of his roiling cloud belts and scuttling moons.  We won’t have to wait much longer for him to put on a similar show in the evening sky, though; he’ll reach opposition in early February of the new year.

 

 

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