The Sky This Week , December 31, 2013 thru January 7, 2014 !

The Sky This Week, 2013 December 31 – 2014 January 7
Happy New Year!
Io_eclipse_131228_01small.jpg

Jupiter, with Io entering eclipse and Ganymede chasing its shadow, 2013 DEC 28, 04:04 – 04:10 UT

The Moon begins the new year as a waxing crescent, with New Moon falling on New Year’s Day at 6:14 am Eastern Standard Time. Luna’s slender crescent can be seen in the southwest about seven degrees northeast of Venus in the bright glow of evening twilight. For the rest of the week her increasing phases pass through the dim constellations of the autumn sky. First Quarter occurs on the 7th at 10:39 pm EST.

Earth reaches perihelion, its closest point to the Sun, on the 4th at 6:59 am. At this moment Earth will be 147,104,792 kilometers (91,406,680 miles) from the center of the Sun. Very little, if any, effect occurs in the amount of sunlight reaching the planet’s surface, as the annual variation in our distance varies by barely three percent. That said, it’s high summer for our friends in the Southern Hemisphere, so if a beach is in your New Year’s plans the south should be your destination.

For those of you who plan to stay up until midnight to welcome in 2014, go outside at the midnight hour and look to the south for the brightest star in the night sky. Easily located just to the southeast of Orion’s three “Belt Stars”, Sirius crosses the meridian as the new year rings in. Right now this is a happy coincidence brought about by the slow precession of the Earth’s rotation axis, but to the ancient Egyptians it was the harbinger of the annual flood of the Nile River when it was seen to rise just before the Sun in mid-summer. This event, known as the heliacal rising of Sothis, was the anchor of the Egyptian calendar and was one of the most celebrated events in their religious calendar. Their civil calendar consisted of 12 months of 30 days with five “intercalary” days added before the secular new year. Over the ages the two calendars would get out of phase with each other, with secular new year corresponding to the heliacal rise about every 1500 years. It is a testament to the duration of their civilization to note that they observed this coincidence three times.

This week we bid a fond farewell to dazzling Venus, which has been a fixture in the southwestern sky for the past several months. The dazzling planet is rapidly overtaking the Earth on her quicker orbit around the Sun and will pass between us and Old Sol on January 11th. This week she seems to plummet from the sky, setting six minutes earlier on successive evenings. She is still very bright and should be relatively easy to spot from a location with a good southwest horizon, and she entertains a very young crescent Moon on the evening of the 2nd. If you have binoculars or a small telescope, point them toward Venus, but only after the Sun has set! You’ll be rewarded with a glimpse of the planet as a very thin crescent, which should be almost identical to the phase the Moon displays when the two objects share the limelight.

As Venus leaves the sky giant Jupiter asserts his role as lord of the night. Old Jove reaches opposition on the 5th at 4:11 pm EST. At this time Earth passes directly between the Sun and Jupiter and the planet rises at sunset and sets at sunrise. This is also when the giant planet is closest to the Earth, and a telescope will show his disc at a generous 46.8 arcseconds’ apparent diameter. In smaller instruments look for the planet’s four large moons, discovered by Galileo 404 years ago. Their constant shifting configurations are a source of wonder every night. Telescopes of four inches or more aperture will show detail in the parallel cloud belts that mark the jovial weather systems, with larger instruments revealing more details. If you happen to catch the Great Red Spot crossing the disc, keep in mind the fact that this feature has a surface area that’s equivalent to the entire surface area of the Earth!

Ruddy Mars now rises shortly after midnight and is still best placed for viewing at the onset of morning twilight. The red planet is drifting eastward among the stars of Virgo, and by the end of the week he’ll be about 10 degrees northwest of the bright star Spica. Mars is wending his way toward opposition in April, but as the Earth catches up to him his apparent disc is gradually growing and he is gradually brightening. Owners of larger telescopes should be able to discern some detail on his dusty face.

Finally, it’s time to start mentioning far-flung Saturn. The ringed planet may now be found in the southeast as morning twilight begins. He’s located in the obscure zodiacal constellation of Libra, the Scales, forming a triangle with the constellations two brightest stars, Zubenelgenubi and Zubeneschamali. If you catch a glimpse of him before twilight interferes you’ll be rewarded with a view of his wide-open rings.

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