Sky & Telescope - January 2021 - 44
JANUARY 2021 OBSERVING
Planetary Almanac
PLANET VISIBILITY (40°N, naked-eye, approximate) Mercury: visible at dusk after the 8th *
Venus: loses altitude at dawn but remains visible throughout January * Mars: transits at dusk and
sets around 1 a.m. * Jupiter: can be seen at dusk until the 16th * Saturn: visible at dusk until the 7th.
Mercury
January Sun & Planets
Date
Jan 1
11
31
21
Sun
Venus
Mercury
1
16
31
Mars
1
Venus
16
31
Mars
Jupiter
Jupiter
Saturn
16
Uranus
Saturn
Neptune
Right Ascension
Declination
Elongation
Magnitude
Diameter
Illumination
Distance
1
18h
45.7m
-23° 01′
-
-26.8
32ƍ 32″
-
0.983
31
20h 54.0m
-17° 27′
-
-26.8
32′ 28″
-
0.985
1
19h 16.8m
-24° 23′
7° Ev
-1.0
4.8″
98%
1.390
11
20h
26.5m
-21° 12′
13° Ev
-0.9
5.3″
90%
1.264
21
21h
26.6m
-15° 51′
18° Ev
-0.8
6.4″
68%
1.050
31
21h 51.2m
-11° 04′
15° Ev
+0.7
8.6″
23%
0.783
1
17h 17.2m
-22° 25′
20° Mo
-3.9
10.7″
94%
1.560
11
18h 11.6m
-23° 11′
18° Mo
-3.9
10.5″
95%
1.594
21
19h
06.0m
-22° 46′
16° Mo
-3.9
10.3″
97%
1.624
31
19h
59.7m
-21° 11′
13° Mo
-3.9
10.1″
98%
1.650
1
1h
39.2m
+11° 14′
107° Ev
-0.2
10.4″
89%
0.899
16
2h 05.5m
+13° 54′
98° Ev
+0.1
9.0″
89%
1.038
31
2h 35.5m
+16° 34′
91° Ev
+0.4
7.9″
89%
1.182
1
20h
19.6m
-20° 05′
22° Ev
-2.0
32.9″
100%
5.994
31
20h
48.5m
-18° 22′
2° Mo
-2.0
32.5″
100%
6.070
1
20h
14.7m
-20° 14′
21° Ev
+0.6
15.2″
100%
10.900
31
20h 29.3m
-19° 27′
6° Mo
+0.6
15.2″
100%
10.961
16
2h 17.0m
+13° 15′
101° Ev
+5.7
3.6″
100%
19.565
16
23h
-5° 32′
53° Ev
+7.9
2.2″
100%
30.512
19.5m
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.org.
16
Uranus
Mars
Neptune
December
solstice
10"
Earth
Uranus
S PLANET DISKS have south up,
to match the view in many telescopes.
Blue ticks indicate the pole currently tilted
toward Earth.
Jupiter
Neptune
X ORBITS OF THE PLANETS
The curved arrows show each planet's
movement during January. The outer
planets don't change position enough in
a month to notice at this scale.
44
JANUARY 2 021 * SK Y & TELESCOPE
Mercury
March
equinox
Sun
Saturn
Venus
June
solstice
Sept.
equinox
http://www.skyandtelescope.org
Sky & Telescope - January 2021
Table of Contents for the Digital Edition of Sky & Telescope - January 2021
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Sky & Telescope - January 2021 - 1
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Sky & Telescope - January 2021 - Cover3
Sky & Telescope - January 2021 - Cover4
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