2°TAURUSAldebaranPleiadesHyadesep Path of Mars(^3) April 1
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Mars passes through the celestial Bull (^)
36 ASTRONOMY • APRIL 2019
Visible to the naked eye
Visible with binoculars
Visible with a telescope
MARTIN RATCLIFFE and ALISTER LING describe the
solar system’s changing landscape as it appears in Earth’s sky.
April 2019: Mars sweeps past the Pleiades
SKYTHIS
MONTH
T
he warmer nights of
April entice skywatch-
ers to spend more time
under the stars. And
this year, several bright
planets add to the celestial
splendor. Evening viewers can
enjoy Mars in the company of
Taurus’ brightest star clusters.
But the best action occurs
before dawn. While Jupiter and
Saturn show off in a dark sky,
Venus and Mercury glow in
morning twilight.
We’ll begin our tour of solar
system wonders low in the west
after sunset. If you’re blessed
with a crystal-clear sky on the
1st, you might glimpse Uranus.
Set against the background
stars of southern Aries, the dis-
tant planet sets just as twilight
fades to darkness. The magni-
tude 5.9 world appears as a
faint dot through binoculars or
a telescope. Uranus disappears
from view after April’s first few
A waxing crescent Moon
adds to the scene April 8. Our
satellite then stands 6° south
of Mars and 8° west of ruddy
Aldebaran, the 1st-magnitude
star that appears to anchor the
Hyades but is actually a fore-
ground object. The following
night, a fatter crescent Moon
lies 6° east of Aldebaran.
As Mars continues its east-
ward march, it passes 7° due
north of Aldebaran on the
16th and traverses the open
cluster NGC 1746 on the 26th.
By the end of April, the planet
forms an isosceles triangle
with the two stars that repre-
sent the Bull’s horns: Beta (β)
and Zeta (ζ) Tauri.
Although Mars excels as
a naked-eye and binocular
object, the view through a tele-
scope proves disappointing.
The diminutive world now
lies far from Earth and shows
a featureless disk less than 5"
in diameter.
Mars doesn’t set until after
11 p.m. local daylight time all
month. Planet watchers can
days as it heads toward con-
junction with the Sun on the
22nd. It will return to view
before dawn in late May.
Mars fares much better
than its far-off cousin. The
Red Planet not only shines
brightly (at magnitude 1.5 in
mid-April), but it also stands
quite high in the west after
darkness falls. The ruddy
world adds a striking focal
point to the star-studded
backdrop of Taurus the Bull.
Mars treks eastward
through the constellation
during April. It spends the
month’s first week between
the glittering Pleiades and
Hyades star clusters. On the
1st, the planet lies 3° south of
the Pleiades (M45) and some
three times farther northwest
of the V-shaped Hyades.
Breathtaking views await
those who scan this region
through binoculars.
then take a break before
Jupiter pokes above the
southeastern horizon. The
giant planet rises shortly
before 1:30 a.m. in early April
and two hours earlier by
month’s end. Gleaming at
magnitude –2.3, it appears
unmistakable against the
backdrop of southern
Ophiuchus and the magnifi-
cent central Milky Way.
Jupiter’s eastward motion
relative to the Serpent-bearer’s
stars comes to a halt during
April’s second week. It then
stands 6.5° west of the
delightful Trifid Nebula
(M20) in neighboring
Sagittarius. Although the
planet then starts heading
westward against the starry
backdrop, it traverses less
than 1° of sky by month’s end.
Be sure to mark your calendar
for the morning of April 23,
when a waning gibbous Moon
passes within 2° of Jupiter.
The best telescopic views
of the planet come once it
climbs highest in the south
A waning gibbous Moon passes 2° from Jupiter on February 23, 2016. The
two have an equally impressive encounter the morning of April 23. ALAN DYER
The Red Planet slides between the brilliant and photogenic Pleiades and
Hyades star clusters during April’s first week. ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY