Astronomy

This map unfolds the entire night sky from sunset (at right) until sunrise (at left).

Arrows and colored dots show motions and locations of solar system objects during the month.

Jupiter’s moons

Io

Europa

S

WE

N

Ganymede

Callisto

ILLUSTRATIONS BY

ASTRONOMY

: ROEN KELLY

SGR

SCT

SER

AQL OPH

HER

DRA

LY R

CYG

VUL

SGE

EQU

LAC

AQR

CAP

MIC

CAS

ARI PEG

PSC

CET

SCL

PHE

FOR

GRU TEL SCO

PA

CrA

Objects visible in the evening

Path (^) o
f (^) the
Moon
Early evening
Sun
Uranus
Pluto
Saturn
Neptune
Mars
Asteroid Eros reaches
opposition December 7
Mars passes 0.04° north of
Neptune on December 7
Vesta
Comet 46P/Wirtanen
should appear brightest
in mid-December
19 18 17 16 15 14 13 12 11 10 9 8 7
1 2 3 4 5 6 7 8 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Callisto
Europa Io
Ganymede
Jupiter
Ceres
Mars
Uranus
Neptune
Saturn
Pluto
Venus
Jupiter
Jupiter
Mercury
Greatest western
elongation is
December 15
Earth
Winter solstice is
December 21
WWW.ASTRONOMY.COM 41
Dots display positions
of Galilean satellites at
7 A.M. EST on the date
shown. South is at the
top to match
the view
through a
telescope.
To locate the Moon in the sky, draw a line from the phase shown for the day straight up to the curved blue line.
Note: Moons vary in size due to the distance from Earth and are shown at 0h Universal Time.
The planets
in their orbits
Arrows show the inner
planets’ monthly motions
and dots depict the outer
planets’ positions at mid-
month from high above
their orbits.