A sample Sky Calendar of a past month is available over the Internet. It
can be accessed via a World-Wide Web browser such at Netscape or
Mosiac, directly at URL:
This month's most striking sights include a very thin crescent Moon
shortly after sunset on Dec. 22, and gatherings of Venus, Mercury,
Mars, and the Moon on the evenings of Dec. 22-24. The Moon appears
near "ringless" Saturn on the evenings of Nov. 29, Dec. 26 and 27, and
can be found near the star Aldebaran in the predawn darkness of Dec. 6
and again at dusk on the same date. The Moon passes near Spica at dawn
on Dec. 17.
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- You'll need a very clear sky and an unobstructed view of the SW horizon
to spot Jupiter, now setting barely 3/4 hour after the Sun. Look very low
in SW half an hour after sunset for the brilliant evening "star" Venus.
Use binoculars for Jupiter, barely above the horizon 13 degrees to Venus'
lower right. Faint Mars might also be seen just 4-1/2 degrees to Venus'
lower right. This may be your last chance to see Jupiter this year; on Dec.
18 it will pass behind the Sun.
Next week a Galileo probe will plunge into Jupiter's atmosphere,
analyzing its surroundings on the way down, while an orbiter relays the
findings and continues to monitor the environment around Jupiter.
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- An hour after sunset the Summer Triangle is high in SW to WNW. Its
stars, in order of brightness, are Vega, Altair, and Deneb. For how many
more weeks can you follow this familiar pattern as it slides lower in the
western evening sky? Try to keep track of the Summer Triangle until at
least the middle of January.
*For observers with telescopes*, the shaded side of Saturn's rings shows
up as a dark band across the face of Saturn. Until February, the unlit
north face of the rings is tipped toward Earth and so the rings are hard to
see to the sides of the planet. In early December 1995, Saturn appears as
a first-magnitude "star" well up in the southern sky soon after nightfall.
For more on observing Saturn and its rings, visit the following Internet
sites:
http://ringside.arc.nasa.gov/
http://newproducts.jpl.nasa.gov/saturn/
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- Look early, 45 minutes after sunset, to see three planets at once. Brilliant
Venus is very low in SW. Binoculars may show Mars 5-1/2 degrees to
its lower right. Saturn, then well up in SSE, reaches its high point in the
south about two hours after sunset, after the other planets have set.
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- At nightfall the waxing gibbous moon is in the east with the Pleiades star
cluster 12 degrees to its left. To the unaided eye even on a moonless
night, the Pleiades appears to consist of only a handful of stars. With
binoculars or a lower-power telescope, dozens of stars may be seen.
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- An hour after sunset the moon is low in E to ENE with the Pleiades, or
Seven Sisters, 8 degrees to its upper left. Aldebaran, the eye of Taurus, is
8 degrees lower left of the moon. Watch the moon approach Aldebaran
and the nearby Hyades star cluster overnight. One and a half hours
before sunup Wednesday, the moon is low in WNW with the Pleiades
10 degrees to its lower right. The moon may actually be covering a star
or two of the Hyades while bright ruddy Aldebaran shines 3 degrees to
moon's upper left.
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- By this evening, the Full Moon has leapfrogged past Aldebaran. Look
for the "Moon before Yule" or "Long Night Moon" very low in ENE at
dusk with first-magnitude Aldebaran 4 degrees to its upper right. The
Pleiades glitter 14 degrees above the bright star. The Arabs named
Aldebaran "the follower", because it follows the Pleiades across the sky.
An hour and a half before sunrise Thursday the moon is low in W to
WNW with Aldebaran 9 degrees to its lower right.
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- Three hours after sunset the moon is in the east with reddish Betelgeuse,
the shoulder of Orion, twinkling 11 degrees to its lower right. At dawn's
first light on Friday the moon is in the W with Betelgeuse 11 degrees to
its lower left.
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- Look low in ENE to E three hours after sunset for the waning gibbous
moon with Betelgeuse in Orion 14 degrees to its right. The Gemini
Twins, Castor 4-1/2 degrees above Pollux, shine within 20 degrees left
of the moon.
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- Three hours after sundown the moon is just risen above the ENE
horizon. Betelgeuse, the shoulder of Orion the Hunter, shines 24 degrees
upper right of the moon. The Gemini Twins, Castor and slightly brighter
Pollux, twinkle 12 to 16 degrees to moon's upper left. An hour later the
moon is higher with Procyon newly risen in the east, 11 degrees to
moon's lower right. At dawn Sunday the moon is high in WSW with the
Gemini Twins to its upper right. Procyon is 10 degrees to moon's lower
left.
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- Four hours after sunset the moon is just risen in the ENE. Look 13
degrees to moon's right for bright Procyon, whose name means "before
the Dog." Within another half hour watch for the rising of the "Dog Star"
itself, Sirius. Look for it in ESE, 26 degrees right of Procyon and a little
lower. Orion's belt points almost directly downward to Sirius, the
brightest nighttime star.
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- Watch the moon as it wanes, or becomes less full each morning until
New Moon, 10 days from today. An hour before sunrise Tuesday the
moon is high in SW and nearing first-magnitude Regulus in Leo. Look
for this bluish star 12 degrees upper left of the moon.
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- Look high in the SW one hour before sunrise Wednesday for the waning
gibbous moon. Regulus, the heart of Leo the Lion, is 5 degrees to its
upper right.
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- The Geminid meteor shower is at its best overnight tonight, from late
evening until first light of dawn. Entering Earth's atmosphere at 78,000
miles per hour, the particles creating the Geminid meteors streak across
the sky noticeably more slowly than meteors from most other showers.
If you see a Geminid meteor, you should be able to trace its path
backward to a point in the sky near Castor and Pollux, the Gemini twins.
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- The moon is near Last Quarter phase high in S an hour before sunup on
Friday. Note the moon appears just under half full. The moon is about
halfway between Regulus, far upper right of the moon, and Spica, far to
moon's lower left.
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- Look for the fat waning crescent moon well up in SSE to S at dawn
Saturday. First-magnitude Spica, in the constellation Virgo, shines 14
degrees to the moon's lower left. Knowing that the moon travels some
13 degrees eastward against the background stars daily, can you guess
will it appear on Sunday at dawn?
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- An hour before sunrise Sunday the crescent moon is well up in SSE
with bright Spica, the spike of wheat in the hand of Virgo, only 1.5
degrees to its lower right. Binoculars will help keep Spica in view as
sunrise approaches. From Michigan, moon and star will appear closest
about an hour after sunrise.
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- At dawn Monday the slender crescent moon is in SSE. Now Spica is 13
degrees upper right of the moon.
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- At dawn Tuesday the thin crescent moon is low in the SE. Using
binoculars, try to see Antares rising 19 degrees to the moon's lower left.
That glow you see on the moon's dark side is earthshine, caused by
sunlight reflecting off the Earth to illuminate the moon.
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- Look for the last easy old moon very low in SE an hour before sunup
Wednesday. Binoculars may show reddish Antares, the heart of the
Scorpion, just rising 8 degrees to the crescent's lower right. Three bright
stars to the moon's right form the head of Scorpius.
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- On Thursday morning, December 21, observers in the southeastern U.S.
have a chance at seeing a difficult very old Moon within 15 hours before
New. Viewers in west Texas might even set a new record, catching the
moon around 13 hours before New. About half an hour before sunrise
Thursday, use binoculars to try to glimpse the exceedingly thin crescent
barely above the ESE horizon, 14 degrees lower left of Antares. If you
miss the *old* crescent moon on Thursday, you'll have a much easier
chance at a remarkably *young* crescent early on Friday evening (details
given under Dec. 22).
Deborah Byrd and Joel Block will be mentioning our prediction of these
Moons on their program, Earth and Sky, aired on many NPR stations on
Wednesday, December 20. See also the article on p. 71 of December
Sky & Telescope; the article should be of interest to all moonwatchers
from the Mediterranean to Texas. If you see the Moon on Dec. 21 alone,
or on both Dec. 21 and 22, your sighting is noteworthy! Please let us
know the details, including times of sightings and optical aid used. Send
your report to Moonwatch, Abrams Planetarium, Michigan State
University, East Lansing, MI 48824.
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- New Moon occurs today at 9:22 p.m. EST. New Moon marks the start
of the lunar cycle, hence the term "new". Look Friday evening about half
an hour after sunset for an easy chance to see a very young moon. Find it
as soon as you can, noting the time of your first sighting, and perhaps set
your own personal record for the youngest moon you have ever seen.
The moon's age will be about 19 or 20 hours from the East Coast, and
23 hours from southern California. (More tomorrow.)
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- Early this morning, winter began with the solstice at 3:17 a.m. EST.
Begin looking early this evening, within 30 minutes after sunset, for the
very young moon, very low in SW to WSW. First locate brilliant Venus
low in SW, than look for the delicate crescent about 20 degrees to Venus'
lower right. All over the continental U.S., wherever skies are clear, the
moon is remarkable easy to see for its tender age. As the sky darkens,
use binoculars to find Mercury 8 degrees left of the moon. Faint Mars is
1-1/4 degrees upper right of Mercury.
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- Look low in SW at dusk for the thin crescent moon with brilliant Venus
8 degrees to its left. Scan the horizon 11 degrees below the moon for a
pair of planets, bright Mercury with faint Mars just over 1 degree to its
upper right. Binoculars will come in handy!
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- At dusk the moon is low in the SW with brilliant Venus, the evening
"star", 10 degrees below. That glow you see on the moon's dark side is
earthshine, from sunlight reflected off the Earth to illuminate the moon.
Mercury and fainter Mars are 1-1/2 degrees apart and about 15 degrees to
Venus' lower right. Binoculars aid in the search!
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- Forty-five minutes after sunset Venus is very low in SW with Mercury
14 degrees lower right. Fainter Mars may be visible in binoculars; look 2
degrees lower right of Mercury.
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- At dusk the moon is in SSW, closing in on Saturn 9 degrees to its left.
Use a telescope for an unusual view of Saturn's rings. The Earth and Sun
are on opposite sides of Saturn's ring plane, giving us a rare view of the
"dark" face of the rings. As a result, the rings appear as a dark band
across the face of Saturn. More tomorrow.
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- An hour after sundown the moon, approaching First Quarter, is in the S
with Saturn 7 degrees to its lower right. Through a telescope, the most
obvious manifestation of Saturn's rings is a dark band across the face of
the planet. Can you also detect the rings to the sides of Saturn? Though
we're viewing their shaded side, they aren't completely dark, because the
rings aren't solid. Some sunlight reflected off the ring particles on their
illuminated side manages to get through the rings to Earth.
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- The First Quarter moon is 90 degrees (1/4 turn) east of the Sun this
afternoon and evening. Note the moon appears half full. At dusk,
binoculars and telescopes show remarkable detail near the moon's
terminator (day-night boundary).
The Great Nebula in Orion's sword contains a very compact quadruple
star known as the Trapezium. Tonight the westernmost of its four stars
undergoes an eclipse by a companion star and so appears fainter than
normal. Usually, the east and west members of the Trapezium appear
equal in brightness at magnitude 6.5. (The southern member is brightest
at mag. 5, and the northern member is faintest at mag. 8.) But tonight the
western star -- the one preceding the others in its motion through the
telescope's field when the scope is at rest -- starts out as faint as the
northern member at 6:30 p.m. EST, and gradually regains its normal
brilliance by 1:30 a.m. EST. Viewers in the Northeast U.S. will be able
to catch this star at minimum brilliance at watch the entire recovery.
Viewers farther west will see the star already partially recovered at
nightfall and follow the rest of its rise to normal.
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- Brilliant Venus is the easiest of three planets very low in the SW. Look
45 minutes after sunset for Venus, the evening "star", with bright
Mercury 13 degrees to its lower right all weekend. Faint Mars lies 4
degrees lower right of Mercury and may require binoculars.
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- In early January, Abrams Planetarium is planning to offer "Celestial
Preview 1996", summarizing next year's spectacular planetary
gatherings. Venus will appear close to Saturn around Groundhog Day
(Feb. 2) and by the end of March will gleam in the western sky for
nearly four hours after sunset. There will be two total lunar eclipses (on
Apr. 3 and Sept. 26). For information on our shows, call (517) 355-
4672. For a recorded message on sky happenings, call our STAR-line at
(517) 332-STAR.
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- An hour after sunset Saturn is well placed for telescopic observation high
in the southern sky. Saturn's rings currently appear as a dark band
crossing the planet's disk. Take advantage of the opportunity to observe
as many of Saturn's satellites as you can, while the rings are faint. Even
with a small telescope, Saturn's brightest moon, Titan, can be seen
farthest west of the planet tonight.