Astronomy

PATHOF THE

PLANETS The planets in December 2018

AUR PER

TAU

ORI

CAE

COL

ERI

LEP

LY N

GEM

CNC

MON

PUP

PYX

VEL

ANT

CRT HYA

SEX

LEO

OPH

HER

DRA

LY R

CEN

CRV

COM

BOÖ

SER

VIR

LIB

SCO

TEL

SCT

SER

LUP

CrB

CVn

LMi

UMa

CMi

CMa

Objects visible before dawn

Celestial equator

Path^ o

f^ the^ S

un^ (eclip

tic)^

Path^ o

f^ the^ S

un^ (eclip

tic)^

Moon phases Dawn Midnight

Sun

Jupiter

Asteroid Harmonia reaches

opposition December 8

Venus shines at its brightest

before dawn in early December

Mercury shines brightly in the

morning sky in mid-December Ceres

Pallas

Herculina

Comet 38 P

Asteroid Hebe reaches

opposition December 27

Juno

9 8 7 6 5 4 3 2 1

31 30 29 28 27 26 25 24 23 22 21 20

Venus

Mars

Mercury

Ceres

Uranus

Saturn

Neptune

Pluto

10"

S

WE

N

Jupiter

The planets

in the sky

These illustrations show the size, phase, and orientation of each planet and the two brightest dwarf planets at 0h UT

for the dates in the data table at bottom. South is at the top to match the view through a telescope.

40 ASTRONOMY • DECEMBER 2018

Planets MERCURY VENUS MARS CERES JUPITER SATURN URANUS NEPTUNE PLUTO

Date Dec. 15 Dec. 15 Dec. 15 Dec. 15 Dec. 31 Dec. 1 Dec. 15 Dec. 15 Dec. 15

Magnitude –0. 5 –4.8 0. 2 8.9 – 1 .8 0. 55. 77 .9 1 4. 3

Angular size 6. 7 " 32 .9" 8.4" 0.4" 31 .8" 15. 2 " 3. 7 " 2. 3 "0. 1 "

Illumination 62 % 37 %86%99% 1 00% 1 00% 1 00% 1 00% 1 00%

Distance (AU) from Earth 1 .00 3 0. 508 1. 120 3. 3296. 2011 0.9 12 1 9. 271 3 0.080 3 4. 574

Distance (AU) from Sun 0. 367 0. 719 1 .4 34 2 .64 15. 350 1 0.06 11 9.864 2 9.9 39 33. 701

Right ascension (2000.0) 15 h 5 9. 7 m 1 4h 2 6.4m 23 h 1 8. 3 m 1 4h 53. 7 m 1 6h 3 9.4m 1 8h 32 .8m 1 h46.9m 23 h00.9m 1 9h 25. 7 m

Declination (2000.0) – 1 8° 13 '– 11 ° 31 '– 5 ° 17 '–9° 51 '– 21 ° 31 '– 22 °4 2 ' 1 0° 27 '– 7 ° 22 '– 22 °0 3 '