Sky and Telescope - January 2017 - 44

JANUARY 2017 OBSERVING
Planetary Almanac

PLANET VISIBILITY: Mercury: Jan. 5 - Feb. 3, dawn, low southeast * Venus: All month, dusk
and after, west * Mars: All month, dusk and after, west * Jupiter: All month, late night to dawn, east
to south-southwest * Saturn: All month, dawn, low southeast.

Mercury

Jan 1

11

21

January Sun & Planets

31

Venus

Date

Diameter

Illumination

Distance

-26.8

32′ 32″

-

0.983

-26.8

32′ 28″

-

0.985

8° Mo

+3.3

9.8″

5%

0.685

-20° 46′

22° Mo

0.0

8.0″

41%

0.845

-22° 10′

24° Mo

-0.2

6.5″

66%

1.038

-22° 26′

22° Mo

-0.2

5.6″

80%

1.191

-13° 47′

47° Ev

-4.4

21.7″

57%

0.769

22h 39.1m

-9° 14′

47° Ev

-4.5

24.0″

52%

0.695

21

23h 14.5m

-4° 30′

47° Ev

-4.6

26.8″

46%

0.621

31

23h 45.6m

+0° 13′

46° Ev

-4.7

30.4″

40%

0.548

1

22h 44.8m

-8° 54′

59° Ev

+0.9

5.7″

90%

1.640

16

23h

26.4m

-4° 18′

55° Ev

+1.0

5.4″

91%

1.741

31

0h

07.3m

+0° 22′

51° Ev

+1.1

5.1″

92%

1.842

1

13h

19.2m

-6° 58′

80° Mo

-1.9

35.5″

99%

5.547

31

13h

26.6m

-7° 35′

108° Mo

-2.1

38.9″

99%

5.068

1

17h 21.8m

-21° 52′

19° Mo

+0.5

15.2″

100%

10.970

31

17h 35.3m

-22° 02′

47° Mo

+0.5

15.5″

100%

10.699

Uranus

16

1h 16.5m

+7° 26′

85° Ev

+5.8

3.5″

100%

20.007

Neptune

16

22h 47.0m

-8° 39′

44° Ev

+7.9

2.2″

100%

30.650

Sun

Mercury
1

16

31
Mars

1

16

Venus

31

Jupiter

Mars

16

Jupiter
Saturn

Saturn
16
Uranus

Right Ascension

Declination

Elongation

1

18h 45.8m

-23° 01′

-

31

20h 54.1m

-17° 27′

-

1

18h 13.0m

-20° 22′

11

17h

56.1m

21

18h

29.6m

31

19h

23.5m

1

21h

59.9m

11

Magnitude

Neptune

PLANET DISKS have south up, to match
the view in many telescopes. Blue ticks indicate
the pole currently tilted toward Earth.

18h

+40°

Vega

16h

14h

The table above gives each object's right ascension and declination (equinox 2000.0) at 0 h 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.

12h

10h

RIGHT ASCENSION

HERCULES

BOÖTES

+30°

+10°
AQUILA

VIRGO

OPHIUCHUS

17

CANCER

Pluto Saturn 23
Mercury

-10°

SAGITTARIUS

Pleiades

C
PTI

10 am

+40°
CYGNUS

PEGASUS
PISCES

Uranus

TAURUS

5
EQUATOR

ORION
Sirius

CORVUS

31
CETUS

ERIDANUS

HYDRA

Venus

Neptune

+30°
+20°
+10°
0°

AQUARIUS

Mars

CANIS
MAJOR

Antares

-10°

2
CAPRICORNUS

-30°

Fomalhaut

SCORPIUS

-40°

22h

ARIES

7
Betelgeuse

20
I

0h

Rigel
Spica

ECL

-30°

2h

Procyon

Jupiter
LIBRA

4h

Jan
11-12

Regulus

0°

6h
GEMINI

LEO

Arcturus

+20°

8h
Castor
Pollux

D ECL I NATI O N

10"

8 am

6 am

4 am

2 am

Midnight

10 pm

8 pm

LOCAL TIME OF TRANSIT
6 pm
4 pm

2 pm

-40°

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

J A N U A R Y 2 0 1 7 * SK Y & TELESCOPE


http://www.SkyandTelescope.com/almanac

Sky and Telescope - January 2017

Table of Contents for the Digital Edition of Sky and Telescope - January 2017

Contents
Sky and Telescope - January 2017 - Cover1
Sky and Telescope - January 2017 - Cover2
Sky and Telescope - January 2017 - 1
Sky and Telescope - January 2017 - Contents
Sky and Telescope - January 2017 - 3
Sky and Telescope - January 2017 - 4
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Sky and Telescope - January 2017 - Cover3
Sky and Telescope - January 2017 - Cover4
Sky and Telescope - January 2017 - SGA17RAL
Sky and Telescope - January 2017 - 90
Sky and Telescope - January 2017 - SGA17R
Sky and Telescope - January 2017 - SGA17RA
Sky and Telescope - January 2017 - SGA17EAL
Sky and Telescope - January 2017 - 94
Sky and Telescope - January 2017 - SGA17E
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Sky and Telescope - January 2017 - SGA17SAL
Sky and Telescope - January 2017 - 98
Sky and Telescope - January 2017 - SGA17S
Sky and Telescope - January 2017 - SGA17SA
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