Astronomy

PATHOF THE

PLANETS

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.

The planets in April 2018

ARI

CET

FOR

SCL

GRU

PsA

AND

TRI

CAS

PEG

SGE

LAC

AQR

CAP

MIC

CrA

SGR

SCT

AQL SER

LY R

CYG

VUL

CRT

UMa

SCO

OPH

HER

DRA

CEN

CRV

COM

CVN

BOÖ

CrB

SER

VIR

LIB

LUP

PSC

Objects visible before dawn

Celestial equator

Moon phases Dawn Midnight

Sun

Pluto Saturn

Neptune

Jupiter

Mars

Mars passes 1.3° south

of Saturn on April 2

Me

rcu

ry

Vesta

17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

30 29 28 27 26

Venus

Mars

Mercury

Ceres

Uranus

Saturn

Neptune

Pluto

10"

S

WE

N

Jupiter

40 ASTRONOMY • APRIL 2018

Planets MERCURY VENUS MARS CERES JUPITER SATURN URANUS NEPTUNE PLUTO

Date April 30 April 15 April 15 April 15 April 15 April 15 April 15 April 15 April 15

Magnitude 0.3 –3.9 0.0 8.2 –2.4 0.4 5.9 7.9 14.3

Angular size 8.0" 10.9" 9.5" 0.6" 43.8" 17.1" 3.4" 2.2" 0.1"

Illumination 4 4% 92% 88% 96% 100% 100% 100% 100% 100%

Distance (AU) from Earth 0.844 1.524 0.982 2.156 4.496 9.745 20.893 30.709 33.463

Distance (AU) from Sun 0.461 0.720 1.514 2.558 5.414 10.066 19.891 29.943 33.543

Right ascension (2000.0) 0h50.3m 3h01.7m 19h06.7m 8h50.7m 15h15.5m 18h38.4m 1h44.9m 23h06.8m 19h30.7m

Declination (2000.0) 2°20' 17°18' –23°18' 29°57' –16°46' –22°15' 10°17' –6°42' –21°30'