Sky & Telescope - January 2025 - 47

+30°
+40°
+10°
+20°
0°
LIBRA
-10°
Mercury
-30°
-40°
SAGITTARIUS
SCORPIUS
10 am
8 am
Jan 24
Antares
6 am
4 am
2 am
Midnight
Spica
21
CORVUS
HYDRA
CANIS
MAJOR
10 pm
8 pm
CAPRICORNUS
Fomalhaut
LOCAL TIME OF TRANSIT
6 pm
4 pm
2 pm
-30°
-40°
The Sun and planets are positioned for mid-January; the colored arrows show the motion of each during the month. The Moon is plotted for evening
dates in the Americas when it's waxing (right side illuminated) or full, and for morning dates when it's waning (left side illuminated). " Local time
of transit " tells when (in Local Mean Time) objects cross the meridian - that is, when they appear due south and at their highest - at mid-month.
Transits occur an hour later on the 1st and an hour earlier at month's end.
apart when it comes to brightness. Saturn
is a respectable magnitude 1.1, but
Venus is an absolute beacon gleaming at
magnitude -4.6 - nearly 200× brighter!
Since both objects easily fit into a
binocular field, there's a fun experiment
you can try. Go outside soon after
sunset and locate Venus in your binos.
Now keep watching and see how long
it takes before you can perceive Saturn
to its left. How about with your eyes
alone? Knowing exactly where to look
will make Saturn much easier to find.
Our second evening event is the
culmination of an alignment featuring
Mars and Gemini's two brightest
stars, Castor and Pollux. The trio form
Dusk, Jan 17
1 hour after sunset
Saturn
Venus
an eye-catching, three-in-a-row line
as they rise in the east-northeast in
fading twilight. After a lead-up spanning
several nights, the configuration
is at last tantalizingly close to perfect -
Mars is ever so slightly to the right of a
line passing through Castor and Pollux.
(True perfection occurs a few hours
before the threesome rise.)
Post-opposition Mars is currently
traveling westward in retrograde
motion - something it will continue to
do until late February, when it reverses
direction and begins trekking eastward.
Over the next few nights, Mars angles
a little bit closer to Pollux and passes
within 2½° of the star on January 22nd.
Dusk, Jan 30 - Feb 1
1 hour after sunset
Moon
Feb 1
Venus
PISCES
Saturn
Moon
Jan 31
Fomalhaut
CAPRICORNUS
Fomalhaut
Looking Southwest
Looking West-Southwest
Moon
Jan 30
¢ Consulting Editor GARY SERONIK
tracks the interactions of the Moon and
planets from his home in British Columbia's
Okanagan Valley.
sk yand tele scope .o r g * JANUARY 2025
47
Finally, on the evening of the 31st, the
Red Planet forms a striking right triangle
with Castor and Pollux.
TUESDAY, JANUARY 21
The best encounter between the Moon
and a bright star this month happens in
the predawn hours today. That's when
a waning gibbous Moon trails behind
1st-magnitude Spica as they rise in
the east-southeast. The star is a touch
more than 1½° from the Moon. As the
morning progresses, the gap between
the two objects increases and will have
more than doubled by the time twilight
lights the dawn sky. And though I said
the Moon's phase is gibbous, it actually
rises 55%-illuminated and very nearly
at last-quarter phase - a mark it will hit
later in the afternoon.
The Moon passes Spica once every
sidereal month, which is 27.3 days long.
That's why it can encounter the same
star (or planet) twice in a calendar
month. But because each return has a
slightly different set of circumstances,
sometimes the Moon passes above or
below Spica, while other times it passes
directly in front of it and we get an
occultation, as we did last November.
Indeed, this morning's conjunction
unfolds as an occultation for observers
in western Africa, but the event ends
before the pair rise in the Americas.
Sirius
ERIDANUS
18h
16h
Vega
HERCULES
AQUILA
14h
BOÖTES
Arcturus
18
OPHIUCHUS
VIRGO
LEO
Regulus
CANCER
Procyon
ORION
Rigel
CETUS
EQUATOR
Neptune
Saturn
Jan 3
Venus
AQUARIUS
-10°
12h
RIGHT ASCENSION
13 -14
10h
8h
Jan Pollux
Castor
GEMINI
Mars
Betelgeuse
0°
Jupiter
TAURUS
9
ARIES
Uranus
6
PISCES
PEGASUS
+20°
+10°
6h
4h
2h
0h
22h
CYGNUS
+30°
+40°
DECLINATION
L
C
E
C
I
T
P
I

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Sky & Telescope - January 2025

Table of Contents for the Digital Edition of Sky & Telescope - January 2025