Sky & Telescope - December 2023 - 47

+30°
+40°
+10°
+20°
0°
Dec 8
-10°
LIBRA
Mars Venus
SCORPIUS
-30°
-40°
10 am
8 am
6 am
4 am
2 am
Midnight
Antares
Spica
CORVUS
HYDRA
CANIS
MAJOR
Fomalhaut
10 pm
LOCAL TIME OF TRANSIT
8 pm
6 pm
Sirius
16h
14h
HERCULES
BOÖTES
Arcturus
VIRGO
5
Procyon
ORION
Rigel
ERIDANUS
Dec 16
CAPRICORNUS
4 pm
SAGITTARIUS
2 pm
EQUATOR
Neptune
CETUS
Mercury
-30°
-40°
The Sun and planets are positioned for mid-December; the colored arrows show the motion of each during the month. The Moon is plotted for evening
dates in the Americas when it's waxing (right side illuminated) or full, and for morning dates when it's waning (left side illuminated). " Local time
of transit " tells when (in Local Mean Time) objects cross the meridian - that is, when they appear due south and at their highest - at mid-month.
Transits occur an hour later on the 1st and an hour earlier at month's end.
wondrous when the Moon is a narrow,
earthlit crescent, as it is this morning
when it's just 13% illuminated. Remember:
The narrower the crescent, the
brighter the earthshine.
SUNDAY, DECEMBER 17
Dawn's waning crescent Moon has
transitioned into dusk's waxing crescent,
and on this evening it pairs up
with Saturn. The famed Ringed Planet
glows at magnitude +0.9 from its perch
a bit more than 2½° above right of the
Moon. Interestingly, you can use the
phase of the Moon to gauge where a
planet is in its apparition. When the
waning crescent is nearby, the planet
is beginning a new apparition; and
Moon
Dec 26
Dec 24 - 25
3:30 am
when it has a conjunction with the
full Moon, it must be close to opposition.
The proximity of tonight's waxing
crescent indicates Saturn is approaching
the end of its run as it inexorably drifts
sunward towards its February 28th solar
conjunction. And though you won't be
able to see it, on that date it'll be the
new Moon that passes near Saturn.
(This Moon-planet trick doesn't work
for Mercury or Venus, however.)
FRIDAY, DECEMBER 22
Moving right along, the Moon
approaches within 3° of magnitude
-2.7 Jupiter as the pair sink toward the
west-northwestern horizon at around
3 a.m. local time. And what phase
Dawn, Dec 30
20 minutes before sunrise
is the Moon? It's a waxing gibbous,
which indicates Jupiter is a little past
opposition. And sure enough, the gas
giant hit that mark just last month, on
November 3rd. If you're not inclined
to get up early to see this pairing, you
don't have to miss out entirely. On the
evening of the 21st, the Moon will be
7° to Jupiter's right, and at nightfall on
the 22nd, it will sit roughly 6½° to its
left. A couple of pretty good consolation
prizes, I'd say.
Moon
Dec 25
Aldebaran
Pleiades
Antares
TAURUS
Moon
Dec 24
Mercury
Mars
Venus
SCORPIUS
SUNDAY, DECEMBER 24
Continuing the trend of early-morning
conjunctions, your reward for getting
up before dawn today will be seeing
the Moon parked on the outer edge of
the Pleiades cluster in Taurus. At its
closest, the waxing gibbous will be less
than 1° from the cluster's brightest
star, 2.9-magnitude Alcyone. Sounds
great, right? But here's the thing. The
Moon is very bright (92% illuminated)
and will be setting when it's closest
to the Pleiades. So, for the best view,
you should try to catch the pair a little
before they're closest, and you'll also
need binoculars to retrieve most cluster
stars from the Moon's overwhelming
glare. Our satellite's path along the
ecliptic in Taurus takes it south of the
cluster, so it'll be close to the Pleiades
for several hours before it gradually
begins to drift away.
Looking West-Northwest
Looking Southeast
¢ Consulting Editor GARY SERONIK
enjoys chasing the Moon even on cold
December nights.
sk yand tele scope .o r g * DECEMBER 2023
47
LEO
Regulus
Dec 2
Uranus
CANCER
Betelgeuse
TAURUS
Jupiter
PISCES
19
AQUARIUS
Saturn
AQUILA
12h
10h
8h
Pollux
GEMINI Dec
Castor
6h
26 - 27
Pleiades
ARIES
22
4h
2h
0h
PEGASUS
+20°
+10°
0°
-10°
22h
RIGHT ASCENSION
CYGNUS
20h
+30°
+40°
Vega
DECLINATION
I
L
C
E
C
I
T
P

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Sky & Telescope - December 2023

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