Sky and Telescope - January 2018 - 44
JANUARY 2018 OBSERVING
Planetary Almanac
PLANET VISIBILITY: Mercury: visible in southeast at dawn through the 19th.
* Venus: out
of sight all month. * Mars: visible in southeast in early morning, highest at dawn. * Jupiter: visible in
southeast in early morning, highest at dawn. * Saturn: visible low in southeast at dawn after the 9th.
Mercury
January Sun & Planets
11
31
21
Date
Venus
Sun
1
16
Mercury
31
Mars
1
16
31
Venus
Jupiter
Mars
16
Jupiter
Saturn
Saturn
16
Uranus
Uranus
Neptune
Neptune
PLANET DISKS have south up, to match the
view in many telescopes. Blue ticks indicate the
pole currently tilted toward Earth.
18h
16h
Vega
14h
12h
RI G HT A S CE NS I ON
HERCULES
Elongation
1
44.7m
Diameter
Illumination
-23° 02′
-
31
20h
53.0m
-26.8
32′ 32″
-
0.983
-17° 31′
1
17h
07.4m
-
-26.8
32′ 28″
-
0.985
11
17h
57.7m
-20° 52′
23° Mo
-0.3
6.7″
62%
0.999
21
18h
59.2m
-22° 53′
21° Mo
-0.3
5.7″
80%
1.179
-23° 28′
17° Mo
-0.3
5.2″
89%
1.303
31
20h 05.4m
-22° 00′
12° Mo
-0.5
4.9″
95%
1.378
1
18h 36.2m
-23° 39′
2° Mo
-4.0
9.8″
100%
1.709
11
19h 30.8m
-22° 38′
1° Ev
-
9.7″
100%
1.711
21
20h 24.1m
-20° 28′
3° Ev
-4.0
9.8″
100%
1.709
31
21h
15.5m
-17° 19′
5° Ev
-3.9
9.8″
100%
1.703
1
14h
47.0m
-15° 09′
56° Mo
+1.5
4.8″
93%
1.956
16
15h
24.3m
-17° 49′
62° Mo
+1.3
5.1″
92%
1.821
31
16h
02.2m
-20° 01′
68° Mo
+1.2
5.6″
91%
1.681
1
14h 58.1m
-15° 49′
54° Mo
-1.8
33.1″²
99%
5.958
31
15h 15.1m
-16° 54′
80° Mo
-2.0
35.8″
99%
5.513
1
18h 05.0m
-22° 32′
9° Mo
+0.5
15.1″
100%
11.034
31
18h 19.4m
-22° 29′
36° Mo
+0.6
15.3″
100%
10.842
16
+8° 56′
89° Ev
+5.8
3.5″
100%
19.896
16
22h
55.1m
-7° 53′
46° Ev
+7.9
2.2″
100%
30.613
8h
+10°
6
VIRGO
OPHIUCHUS
Jan
30-31
-10°
Mercury
12
Saturn
Jupiter
9
EC
Spica
LIP
TI
CANCER
26
Betelgeuse
TAURUS
10 am
0h
22h
+40°
CYGNUS
ARIES
PEGASUS
PISCES
24
Uranus
EQUATOR
ORION
Neptune
21
+20°
+10°
0°
-10°
Sirius
CORVUS
+30°
AQUARIUS
Rigel
CETUS
ERIDANUS
HYDRA
CAPRICORNUS
CANIS
MAJOR
Antares
Venus
-30°
Fomalhaut
SCORPIUS
-40°
2h
Pleiades
Jan
1-2
C
Mars
SAGITTARIUS
4h
GEMINI
Procyon
0°
LIBRA
6h
Castor
Pollux
Regulus
AQUILA
Distance
31.2m
10h
LEO
Arcturus
+20°
Magnitude
1h
BOÖTES
+30°
-30°
Declination
18h
The table above gives each object's right ascension and declination (equinox 2000.0) at 0h Universal Time on selected dates,
and its elongation from the Sun in the morning (Mo) or evening (Ev) sky. Next are the visual magnitude and equatorial diameter.
(Saturn's ring extent is 2.27 times its equatorial diameter.) Last are the percentage of a planet's disk illuminated by the Sun and
the distance from Earth in astronomical units. (Based on the mean Earth-Sun distance, 1 a.u. is 149,597,871 kilometers, or
92,955,807 international miles.) For other dates, see skyandtelescope.com/almanac.
10"
+40°
Right Ascension
D ECL I NATI O N
Jan 1
8 am
6 am
4 am
2 am
Midnight
10 pm
8 pm
LOCAL TIME OF TRANSIT
6 pm
4 pm
2 pm
The Sun and planets are positioned for mid-January; 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). "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.
44
JA N UA RY 2 018 * SK Y & TELESCOPE
-40°
http://www.skyandtelescope.com/almanac
Sky and Telescope - January 2018
Table of Contents for the Digital Edition of Sky and Telescope - January 2018
Contents
Sky and Telescope - January 2018 - Cover1
Sky and Telescope - January 2018 - Cover2
Sky and Telescope - January 2018 - 1
Sky and Telescope - January 2018 - Contents
Sky and Telescope - January 2018 - 3
Sky and Telescope - January 2018 - 4
Sky and Telescope - January 2018 - 5
Sky and Telescope - January 2018 - 6
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Sky and Telescope - January 2018 - 9
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Sky and Telescope - January 2018 - Cover3
Sky and Telescope - January 2018 - Cover4
Sky and Telescope - January 2018 - SGA18SAL
Sky and Telescope - January 2018 - 90
Sky and Telescope - January 2018 - SGA18S
Sky and Telescope - January 2018 - SGA18SA
Sky and Telescope - January 2018 - SGA18EAL
Sky and Telescope - January 2018 - 94
Sky and Telescope - January 2018 - SGA18E
Sky and Telescope - January 2018 - SGA18EA
Sky and Telescope - January 2018 - SGA18RAL
Sky and Telescope - January 2018 - 98
Sky and Telescope - January 2018 - SGA18R
Sky and Telescope - January 2018 - SGA18RA
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