December 2017 Sky-Watch:  Xmas Program and Meteor Shower by Dennis Herrmann


Thirty years ago, December 1987, I led my astronomy students at Kent County High School in writing and producing a Christmas Program in the planetarium.  Along with the help of the radio station at school, WKHS-FM, the program was presented to the public and to classroom students from our county schools.  Each year since 1987, we have done the same thing.

This year we present the 31st annual Xmas Program on December 15, 18, 19, 21, and 22 at 7 p.m. at the KCHS planetarium.  We never charge admission and always provide holiday refreshments.  We hope many of you and your families and friends will join us for this year’s program, “The Magic of Xmas; the Magic of the Planetarium.”  It remains, as always, our gift to the community and is a unique way to help celebrate this wonderful time of year.

The year’s richest and most reliable meteor shower, the Geminids, will peak on the night of December 13/14, without any Moon interference.  The Moon’s phase is slim crescent; and it does not rise until 3:30 p.m.  The Geminids appear to come from the area of the sky where we see the constellation Gemini.  Gemini rises around sunset time, nearly due east, and is nearly overhead by 2 a.m.  The best meteor views will come then on the morning of December 14th, between midnight and 4 am.  Under clear, dark sky conditions we may expect to see upwards to 120 meteors per hour!

Geminids Meteor Shower

Mars rises in the southeast sky at magnitude +1.7 around 3:30 a.m. in early December, where it will be very close to Spica; brightest star in Virgo.  Mars is only half as bright as Spica this month, but bright enough so that its ruddy color will make a nice contrast of color with the blue-white star Spica.

Jupiter also rises in the east about 75 minutes after Mars.  Jupiter is much brighter at –1.7 magnitude and is found among the stars of Libra the Scales.

Last month a close conjunction of the two brightest planets as seen from Earth, Venus and Jupiter, occurred behind cloudy skies for us; so we missed it.  But we will have another chance to see a good planetary conjunction on December 31st.  One hour before sunrise, looking southeast, Mars may be seen just 3 degrees to the right of Jupiter, with the bright star of Libra, Zubenelgeneubi, right between them.  During the first week of January 2018, they will be even closer (just 0.2 degrees) apart!  By the way, Zubenelgenubi is my favorite star name.  Pronounced:  Zoo Ben L gen Oo Bee.

Size comparison – Mars, Jupiter, Saturn, Venus, Mercury, etc.

During the month of December, we can watch Mars draw closer to Jupiter, from 16 degrees apart on the 1st, down to 3 degrees on the 31st.  In between on the 13th, the waning crescent Moon may be seen above Mars, with Jupiter 11 degrees below the red planet.  On December 14th, an even slimmer crescent Moon will be 5 degrees to Jupiter’s upper left.

This month’s Full Moon on December 3 will gather a lot of attention and receive media hype because full phase happens only 17 hours before the Moon makes its closest approach to Earth (perigee) during its monthly orbit.  This coincidence makes this the largest full moon of 2017 – some 7% more than average.  If we observe this Full Moon low above the eastern horizon we will be surprised by its size.  But this is mostly an illusion caused when viewing the Moon near familiar objects in the foreground.  Our minds are “tricked” into perceiving the Moon as larger.  The media will refer to it as a “Super Moon.”

The Moon will also Occult the brightest star in Taurus, Aldebaran, on December 30 between 6 and 7 p.m. EST.  The dark side of the waxing gibbous Moon will cover the star for about one hour, with it coming back to view as the brightly lit side moves past it.  This event is an occultation and is fun to observe with binoculars.

Merry Christmas; keep looking up and watching God’s glorious night sky – and come to the Xmas program!!!


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