Abrams Planetarium Skywatcher's Diary
December 1998
To the reader:
The Skywatcher's Diary for December 1998 has been prepared by
Robert C. Victor. Credit to the author and to
Abrams Planetarium, the
Department of Physics and Astronomy at
Michigan State University, and mention of our
Sky Calendar, would be
appreciated.
A sample issue of the Sky Calendar is available over the Internet. It
can be viewed via the World-Wide Web at
http://www.pa.msu.edu/abrams/SkyCalendar/Index-t.html
If you would like a printed sample of the December issue, please send a long,
self-addressed stamped envelope to:
December Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
Each month, the Department of Physics and Astronomy at Michigan State
University makes the Skywatcher's Diary available over the Internet. It can be
accessed at
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Diary.html
Current and back-issues of the Skywatcher's Diary are available in our archives
at
ftp://www.pa.msu.edu/pub/swd/
Evening Planets: Bright Jupiter (mag. -2.5 to -2.3) is high in SSE to SSW at dusk, while Saturn (mag. +0.2 to +0.4) is in ESE to high in SE, 39 to 35 degrees E of Jupiter. On what date will you first spot Venus as an evening star? Find a place with an unobstructed view toward SW to WSW, and start looking about 15 minutes after sunset. Venus gets easier to see as the month progresses; from lat. 40 deg. N, Venus sets after the Sun by just 30 minutes on Dec. 3, by 3/4 hour on Dec. 15, and by one hour on Dec. 26. Catch Venus and Jupiter when they're 60 degrees apart on Dec. 28, and then look nightly and watch the gap between the two brightest planets narrow until their spectacular close conjunction on Feb. 23.
Morning Planets: Reddish Mars is well up in SSE to S an hour before sunrise, and closes from 22 degrees to just 7 degrees upper right of blue-white Spica. In December, Mars brightens from mag +1.4 to +1.0, ending as a close match in brightness to Spica. Mars will pass Spica on Jan 12. In April-May 1999 Mars will outshine even the brightest star, Sirius. Prepare to begin a long series of photos of Mars against background stars in early January; see next month's Sky Calendar. Mercury best of year: See Dec. 7, 12-16, 19, 22, 26.
From certain sections of North America, telescopes may show one of this month's two occultations of Aldebaran by a nearly Full Moon. See Dec. 2 and 30.
Skywatcher's Diary: December 1998
About 2 hours after sunset, bright Jupiter is near its high point in the south, with Saturn in SE, nearly 40 degrees to Jupiter's left. Aldebaran is in E, just over 40 degrees to Saturn's lower left. Tonight the Moon is nearly halfway from Saturn toward Aldebaran. Check Moon's position again on Wednesday and Thursday evenings.
From all of U.S. except Northwest and Alaska, look for Sun and Moon simultaneously, just before sunset. The Sun and Moon are in opposite directions. You'll need unobstructed views toward WSW and ENE horizons. An hour after sunset, Michigan skywatchers will find Aldebaran 8 degrees to Moon's lower left. From all locations as night progresses, Moon gets about 0.5 degrees closer to Aldebaran each hour. On Thursday morning, this star disappears behind the Full Moon, an event best seen from northwestern U.S., where sky is still dark when Moon covers star. Since the Moon is bright, use a telescope to see the event. On W Coast, time of star's disappearance ranges from 5:44 a.m. in Vancouver to 6:05 a.m. in Los Angeles. Event can be seen in bright twilight as far east as Los Angeles, Las Vegas, Salt Lake City, and Billings MT, with Moon and star about to set. For more: Visit the website
http://www.sky.net/~robinson/iotandx.htm
One hour after sunset, the Full Moon is very low in ENE, with Aldebaran, eye of Taurus, 7 degrees to its upper right. On Friday an hour before sunrise, look for Betelgeuse low in W, 12 degrees to Moon's lower left. Aldebaran is 13 degrees to Moon's lower right.
Moon rises farthest north of east tonight and Saturday, about 1-1/2 hours after sunset tonight (from latitude of lower Michigan) and an hour later on Saturday. Three hours after sunset tonight, look for Orion the Hunter rising in E, to Moon's right. Orion's brightest stars are Betelgeuse in E and Rigel in ESE. Midway between them lies Orion's belt, a vertical line of three stars.
Season of Light is presented at Abrams Planetarium Fridays and Saturdays at 8:00 p.m. and Sundays at 4 p.m., through Dec. 20. Some of the world's diverse holiday traditions, past and present, will be shown, along with possible explanations of the Star of Bethlehem. For more information, call (517) 355-4672.
Three hours after sunset, the Moon has just risen in ENE. Pollux and Castor, heads of the Gemini twins, are 12 to 14 degrees to Moon's upper left. In another hour, watch for the rising of Procyon in east, within 15 degrees to Moon's lower right. An hour before sunrise on Sunday, the Moon is well up in W, with the twins 10 to 14 degrees upper right, and Procyon 13 degrees lower left.
Rusty Rocket's Last Blast (our family show) is presented 2:30 p.m. Sundays at Abrams Planetarium. Our feature show, Season of Light, is presented at 4 p.m. today and 8 p.m. on Fridays and Saturdays. Both shows will conclude on Dec. 20. For information on our shows, call (517) 355-4672.
Some 4-1/2 hours after sunset from northern U.S., earlier from southern U.S., watch for the rising of Sirius, the "Dog Star". Orion's belt points downward toward this star. This evening, the Moon, N of E, Procyon in E, and Sirius in ESE lie in a nearly straight line.
The Moon rises within 5 hours after sunset. About 6 hours after sunset, look for the star Regulus 13 degrees to Moon's lower left. By an hour before sunup on Tuesday, the Moon is in SW with Regulus 10 degrees upper left. Mercury is then very low in ESE and brightens rapidly in coming days, quadrupling in brilliance Dec. 8-20. The 3rd and 4th weeks of this month are the best of this year for seeing Mercury in the morning sky.
The star Regulus is occulted by the waning gibbous Moon at or just after moonrise in late evening, as seen from Florida except the western panhandle, and from bordering SE Georgia. Use a telescope or binoculars to see the star's reappearance. Elsewhere in eastern U.S., the northern (left) edge of Moon narrowly misses the star around 11 p.m. EST. From Miami, Regulus reappears on the Moon's dark side at 11:40 p.m. By an hour before sunup on Wednesday, the Moon is high in SW, with Regulus about 3 degrees to its right.
An hour before sunrise on Thursday, Moon is high in S, beneath the hindquarters of Leo. Follow the Moon until shortly after midday, when it sets in the west. On Thursday the Moon is at Last Quarter phase, 90 degrees or one-quarter circle west of the Sun. Note the Moon is half illuminated.
An hour before sunrise on Friday, the fat crescent Moon is high, east of due south, with Mars in SSE, 10 degrees to Moon's lower left. Spica is 16-1/2 degrees lower left of Mars.
An hour before sunrise on Saturday, waning crescent Moon is in SSE with Mars just to its right. Spica is 16 degrees lower left of Mars.
On Sunday an hour before sunup, Moon is in SE to SSE, with Spica 6 degrees lower right. Mars is 15-1/2 degrees upper right of Spica. Mercury, now brightened to zero magnitude, is very low, about 30 degrees S of due east, and is in fine view rest of month.
Tonight, from late evening until first light of dawn, the Geminid meteor shower is near its peak. On Monday an hour before sunrise, the waning crescent Moon is in SE, with Spica 12 degrees upper right. Mars is 15 degrees upper right of Spica. Arcturus is 28 degrees to Moon's upper left, and Mercury is same distance to Moon's lower left.
An hour before sunup on Tuesday, the thin crescent Moon is in SE, with Mercury about 17 degrees to its lower left. Look again on Wednesday and Thursday mornings.
An hour before sunrise on Wednesday, look low, between SE and ESE, for a beautiful crescent Moon and Mercury about 6 degrees to its lower left.
Last chance to see the old Moon: Thursday morning, starting an hour before sunup, look for a thin crescent just a few degrees up in ESE, about 6 degrees lower left of Mercury.
One hour after sunset, find bright Jupiter well up in S, and Saturn in SE 37 degrees to Jupiter's left. A straight line from Jupiter through Saturn extended 43 degrees ends near the star Aldebaran in E. As sky darkens, look for the Pleiades or Seven Sisters star cluster 14 degrees above Aldebaran.
The Moon is New today at 5:42 p.m. EST, and is not visible.
First chance to see the young Moon: Find a place with an unobstructed view of the horizon between SW and WSW. About 20 minutes after sunset, if the sky is clear, look for Venus just a few degrees above the horizon. The very slender crescent Moon is just 4 degrees to Venus' upper right, or to its right from southeastern U.S. This evening's first view of the lunar crescent marks the beginning of the Islamic holy month of Ramadan. The Moon's age (time elapsed since New) is less than 24 hours from lower Michigan and farther east.
An hour before sunrise on Sunday, bright Mercury, low in SE to ESE, appears farthest from Sun, 22 degrees. Watch for the rising of Antares 7 degrees to Mercury's lower right.
Two days after New, the crescent Moon is easy to see low in SW by 20 minutes after sunset. Look for Venus 10 degrees to Moon's lower right. As sky darkens these evenings of the thin crescent, look for earthshine on the Moon's dark side.
Twenty minutes after sunset, look for the Moon is SW with Venus 21 degrees to its lower right. As twilight deepens, look for the Summer Triangle in the west. Its brightest star is Vega in WNW. Altair is in WSW, 28 degrees to Moon's upper right. The top of the triangle is marked by Deneb. Although Winter begins tonight at 8:56 p.m. EST, the Summer Triangle remains visible at dusk until the middle of January.
Early this evening, the Moon is nearly midway between the two brightest planets: One-half hour after sunset, find the crescent Moon in SSW. Jupiter is high in southern sky, 34 degrees to Moon's upper left, while Venus is low in SW, nearly as far to Moon's lower right. As sky darkens, extend the Moon-Jupiter line leftward to Saturn in SE and Aldebaran in E. For rest of month, watch the Moon move along that line. On Wednesday an hour before sunup, look low in SE for Mercury with Antares 6 degrees lower right.
An hour before sunrise on Thursday, look in SSE to S to find Mars and Spica 10 degrees apart and closing. They are nearly equal in brightness, at first magnitude, but differ in color.
An hour after sunset, high in the sky just W of due south, find the crescent Moon, one-third full. Bright Jupiter is 7 degrees to its upper left. Look again on Friday evening.
It's easy to spot Venus early this evening: It now follows the Sun across the sky by one hour, so about 30 minutes before sunset, note the Sun's location in relation to your local landscape. Note the time and return exactly an hour later, and almost exactly where the Sun was, you'll find Venus! About an hour after sunset, the fat crescent Moon is high in south, with Jupiter 6 or 7 degrees to its right. Saturn is in SE, nearly 30 degrees to Moon's left.
The Moon rises in east today within half an hour after midday, when Sun is due south. Follow the Moon for the rest of the afternoon, as it follows Sun by just over 90 degrees. The Moon has passed First Quarter phase and appear slightly more than half full. By an hour after sunset, the Moon is in SSE. Saturn is then 15 degrees to the Moon's left, and Jupiter 20 degrees to the Moon's right. An hour before sunup on Sunday, look for the first magnitude star Antares, heart of Scorpius, low in SE, 8 degrees right of brighter Mercury.
Moon is in SE an hour after sunset, with Saturn 2 or 3 degrees above it or to its upper left. Bright Jupiter lies 35 degrees to their west.
Just after sunset the waxing gibbous Moon is in ESE. As sky darkens, look for Saturn 14 degrees to Moon's upper right, and Aldebaran about twice as far to Moon's lower left. Look nightly, and see what event involving the Moon will happen on Wednesday.
An hour after sunset the waxing gibbous Moon is in ESE. Look for Aldebaran 14 degrees to Moon's lower left, and Saturn about twice as far to Moon's upper right. Can you predict where the Moon will appear on Wednesday evening?
Aldebaran disappears behind the dark edge of Moon at sunset near a line from Thunder Bay Ontario, past Buffalo NY, to Philadelphia. The farther NE of that line you are, the darker the sky when the star goes behind the Moon. Reappearance of star on Moon's bright side is visible over a broader area of eastern U.S.: Around sunset from Duluth MN to Savannah GA, and in darker skies NE of that line. Since the Moon is bright, use a telescope to see these events. Here are times Aldebaran is covered for some eastern cities: Boston 4:52-5:46 p.m. EST; New York 4:49 p.m. (in bright twilight) to 5:42 p.m.; Washington DC 4:45 p.m. (in daylight) to 5:38 p.m.; Toronto 4:56 p.m. (in bright twilight) to 5:40 p.m.; Lansing, MI 4:55 p.m. (before sunset) to 5:36 p.m. (in bright twilight). For more on this occultation, visit the website:
http://www.sky.net/~robinson/iotandx.htm
For the rest of the night until about 3 hours before sunrise on Thursday, the Moon slowly pulls away from Aldebaran. Look hourly until bedtime.
Orion is up before nightfall! An hour after sunset tonight, look in the east for Betelgeuse, the Hunter's shoulder, 11 degrees to Moon's lower right. Rigel, Orion's foot, is 19 degrees right of Betelgeuse. Midway between these two bright stars, find the Hunter's belt, a vertical line of three stars. Extend Orion's belt upward to find Aldebaran, eye of Taurus the Bull. Since last evening, the Moon has moved 15 degrees to that star's lower left.
Showing at Abrams Planetarium two weekends only,January 8-10 and 15-17:
Celestial Preview 1999. This live, informal show uses our Digistar to preview the best of the year's evening events: Spectacular planet gatherings in the first half of '99, the unusual brilliance of Mars in spring, and of Jupiter and Saturn in autumn, their best showings in several years. Our family show, Rusty Rocket's Last Blast, will be presented Sundays at 2:30 p.m., beginning January 10. For a recorded message about our shows, call (517) 355-4672.
