5°PEGASUSCETUSMercuryVenusFebruary 28, 30 minutes after sunset
Looking westAn inner planet rendezvous (^)
36 ASTRONOMY • FEBRUARY 2018
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.
February 2018: A morning planet trio
SKYTHIS
MONTH
fter a couple of months
when no bright planet
graced the evening sky,
the tide starts to turn in
February. Both Mercury
and Venus pop into view short-
ly after the Sun sets late this
month. Their brief appearances
herald fine performances in the
coming weeks. These two inner
worlds join the more distant
planets Uranus and Neptune
as worthy evening targets.
after sundown. The planet
shines brilliantly, however, at
magnitude –3.9, and shows up
despite the bright twilight.
If you target Venus with
binoculars, you also might
spot Mercury. The innermost
planet passes on the far side of
the Sun on February 17 and
reappears at dusk soon there-
after. By the 28th, it lies 2.3°
to Venus’ lower right. Because
Mercury shines more dimly, at
magnitude –1.4, and has a
lower altitude than its neigh-
bor, glimpsing it requires an
unobstructed horizon and a
clear, haze-free sky.
The two planets edge closer
in the following days, and will
pass 1.4° from each other in the
first week of March. Mercury
goes on to have its finest eve-
ning appearance of 2018 in
mid-March. Venus climbs more
slowly and will appear con-
spicuous in evenings through
spring and summer.
Distant Neptune lies near
Venus in late February, passing
within 1° of the brilliant planet
the evenings of February 20
But the month’s best planet
action occurs before dawn.
Mars, Jupiter, and Saturn con-
gregate in the morning sky,
where they provide excep-
tional views for casual and
serious observers alike.
Our tour of the night sky
begins low in the west after
sunset in late February. On
the 28th, Venus lies only 12°
east of the Sun and stands 5°
above the horizon a half-hour
and 21. But the eighth planet
glows at 8th magnitude and
will be invisible in twilight.
Fortunately, Neptune is far
better positioned in early
February. On the 1st, the
planet stands 10° high in the
west-southwest as the last
glints of twilight fade away.
You can find it through bin-
oculars against the backdrop
of Aquarius. First, locate 4th-
magnitude Lambda (λ)
Aquarii. Neptune lies 1.1° due
east (upper left) of this star.
The pair dips lower with each
passing day and disappears in
twilight during February’s
second week.
Uranus stands halfway to
the zenith in the southwest
as twilight closes in early
February. The 6th-magnitude
planet resides among the
background stars of eastern
Pisces. On the 1st, it lies 3°
from both 4th-magnitude
Omicron (ο) Piscium and
5th-magnitude Mu (μ) Psc.
Uranus’ eastward motion car-
ries it to a point 2.3° west of
Omicron on the 28th.
Uranus sets shortly after
11 p.m. local time in early
February and close to two
hours before that at month’s
end. You’ll get your best views
through a telescope in early
evening when the planet still
lies reasonably high. The ice
giant’s 3.5"-diameter disk
glows with a distinctive blue-
green hue.
Although the midnight
sky is devoid of planets for
most of February, the wait for
the next batch of solar system
worlds is well worth it.
A trio of spectacular plan-
ets stretches out across the
southeastern sky before dawn
all month. Jupiter, Mars, and
Three planets adorned the sky in June 2016. Mars is the brightest object left of center, and Saturn lies to its left next
to the Milky Way. Jupiter gleams above the horizon at right. The same three planets return in February. ALAN DYER
Mercury and Venus hug the western horizon during twilight on February’s
final few evenings. ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY
A