Sky and Telescope - February 2018 - 47

much earlier as the month progresses,
only gaining a half hour between February 1st when it rises at 2:30 a.m. local
time and February 28th when it rises
around 2 a.m.
An interesting observing project
throughout February is to compare
Mars with Antares, which means "rival
of Mars." The separation between the
two is 8° as the month begins, is less
than 6° from February 7th to 16th, and
shrinks to a minimum of about 5° on
February 11th and 12th. These similarcolored points of light are also similar
in brightness during this month of their
conjunction. Though variable, Antares
usually shines at around magnitude 1.0.
Mars starts the month at magnitude
1.2, is 1.1 on the American morning of February 11th, 1.0 on the 16th,
and +0.8 by month's end (though dust
storm activity can change its predicted
brightness a bit).
In the eyepiece, Mars increases from
about 5½″ to just over 6½″ in angular
diameter during February, still too
small to show any real detail.
Saturn comes up a little before 5
a.m. as February starts and a little
after 3 a.m. as the month ends. The
ringed planet shines at magnitude +0.6
all month in Sagittarius. Mars closes

December
solstice

Uranus

March
equinox

Jupiter

Saturn

Venus

Mercury

Neptune

June
solstice

ORBITS OF THE PLANETS
The curved arrows show each planet's movement during February. The outer planets don't
change position enough in a month to notice at this scale.

the gap between it and Saturn from 31°
to around 17° during February, shining about halfway between Saturn and
Jupiter around February 19-21.
Saturn isn't very high in the southeast as morning twilight begins but its
current starry background is fascinating. It hovers some 3° above the topmost star of the Teapot of Sagittarius.
Not far from the planet are such deepsky marvels as the globular cluster M22,
below and to the left, at 4° separation
on the 1st, 3° separation on the 14th,
and 2° separation on the 28th, and

Dusk, Feb 27 - Mar 1

Just after dark

1 hour after sunset

Moon
Feb 23

Moon
Feb 27

LEO
γ

Aldebaran

Moon
Feb 28
Regulus

Betelgeuse

Moon
Mar 1

ORION

Denebola
Rigel

Looking South, high in the sky

Sept.
equinox

Sun

Mars

Feb 23-24
Moon
Feb 24

Earth

Looking East

the Small Sagittarius Star Cloud (M24)
some 4° to 5° above. If you turn a telescope on Saturn itself, you can see that
although the planet's globe is still less
than 16″ wide in equatorial diameter,
the glorious rings have a much greater
span and remain tilted at 26° for our
line of sight, nearly their most open.

SUN AND MOON
The Sun undergoes a partial eclipse on
February 15th for observers in most of
Antarctica and southern South America.
The Moon is near its last quarter
phase when it poses just over 6° upper
right of Jupiter before dawn on February 7th. The next morning, the Moon
is almost 8° to the planet's left. A thin
waning lunar crescent hangs some 2°
above Saturn at dawn on February 11th.
A hair-thin waxing lunar crescent ﬂoats
just under 3° to the upper left of Venus
on February 16th, but the two must be
observed low near the west-southwest
horizon only about 20 to 30 minutes
after sunset. A slightly gibbous Moon is
about 4½° left of Aldebaran at nightfall
on February 23rd. The nearly full Moon
beams above Regulus on the evening of
February 28th and occults the 1st-magnitude star for observers in northern
North America; see page 49.
¢ FRED SCHAAF teaches astronomy at
Rowan University and Rowan College
in Gloucester County, both in southern
New Jersey.
sk yandtelescope.com * FE B RUA RY 2 018

http://www.skyandtelescope.com/

Sky and Telescope - February 2018

Table of Contents for the Digital Edition of Sky and Telescope - February 2018