Sky & Telescope - January 2024 - 46

JANUARY 2024 OBSERVING
Sun, Moon & Planets by Gary Seronik
To find out what's
visible in the sky from
your location, go to
skyandtelescope.org.
Planets Dance at Dawn
Venus, Mercury, and Mars adorn the morning sky.
FRIDAY, JANUARY 5
The Moon encounters Spica on a
monthly basis throughout the year,
but some of those meetings are more
visually rewarding than others. For
instance, there are several that are simply
unobservable because they happen
in the autumn months when the star
is lost in the Sun's glare. Strike those
off the list. And then there are some
where the Moon may not get especially
close to Spica. Call those interesting but
perhaps not worth more than a glance.
And then there are a few in which the
two objects have a separation of 5° or
less - close enough to occupy the same
binocular field. Those are the ones to
get excited about.
As it happens, 2024 is a banner year
for Spica-and-Moon conjunctions,
starting this morning when they rise
in the wee hours with about 4° separating
them. The
waning lunar
crescent trails the
star and clears the
east-southeastern
horizon around
1:30 a.m. local
time. By the time
twilight seriously
brightens the sky,
the Moon's eastward
motion puts
it an additional 2°
farther from Spica.
But as enjoyable
as this particular
conjunction is,
you ain't seen
nothin' yet! On
two occasions this
year, the Moon
Jan 3 - 5
2 am
Moon
Jan 3
46
JANUARY 2024 * SKY & TELESCOPE
will glide right up to Spica and eclipse
the star! One occultation happens in
July and another in November. Watch
this space for more on those.
MONDAY, JANUARY 8
If you don't want to wait until July to
see the Moon cover a bright star, well,
you might not have to. As noted in
Celestial Calendar (page 48), observers
across much of the western U.S. and
Canada will get to see the 26½-day-old
waning lunar crescent occult Antares.
Since Bob King details that event in
his column, we won't dwell on it here.
Instead, let's take in the big-picture perspective
and appreciate a truly wonderful
gathering at dawn.
At around 6 a.m., cast your gaze to
the southeastern horizon and soak up
the sight of the Moon forming a large
right triangle with brilliant Venus
(gleaming at magnitude -4.0) and
Mercury (holding its own at magnitude
-0.2). Both planets are currently putting
on quite a show. Venus is as favorably
positioned as it will be in the morning
sky all year for Northern Hemisphere
observers, while Mercury is enjoying
the first of three excellent 2024 dawn
appearances. Indeed, this morning it's
only one day removed from its highest
dawn altitude during this apparition.
If the weather doesn't cooperate, you
have an excellent second opportunity
to view this collection of solar system
wonders in a slightly different configuration.
On the following morning
(the 9th), the trio arranges itself into a
second right triangle, but this time the
Moon is lower, thinner, and closer to
Mercury. If we include Antares in our
geometry, then our shape is a 12°-wide
box instead.
tThese scenes are drawn for near the middle of North America (latitude
40° north, longitude 90° west). European observers should move
each Moon symbol a quarter of the way toward the one for the previous
date; in the Far East, move the Moon halfway. The blue 10° scale bar is
about the width of your fist at arm's length.
VIRGO
Moon
Jan 4
Antares
Spica
Moon
Jan 5
Mars
Looking East-Southeast
Looking Southeast
Looking South-Southeast
10°
Mercury
Moon
Jan 9
Dawn, Jan 7- 9
30 minutes before sunrise
Venus
Moon
Jan 8
Occultation for much
of North America!
Moon
Jan 7
SCORPIUS
http://www.skyandtelescope.org
Sky & Telescope - January 2024

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