Sky & Telescope - October 2023 - 47

+30°
+40°
0°
+10°
+20°
Mercury
CORVUS
-20°
-30°
-40°
HYDRA
CANIS
MAJOR
10 am
8 am
6 am
4 am
2 am
Fomalhaut
LOCAL TIME OF TRANSIT
Midnight
10 pm
21
CAPRICORNUS
8 pm
SAGITTARIUS
6 pm
Oct 18
Antares
4 pm
SCORPIUS
2 pm
12h
10h
LEO
Regulus
Betelgeuse
Venus
Procyon
ORION
Sirius
Rigel
CETUS
ERIDANUS
-20°
-30°
-40°
The Sun and planets are positioned for mid-October; 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.
SATURDAY, OCTOBER 7
Next on the lunar agenda: a meeting
in Gemini with Castor and Pollux,
the constellation's brightest stars. You
can think of this as being two events in
one. As the waning crescent Moon rises
(shortly after midnight on the morning
of October 7th), it's a bit more than
2½° right of Pollux. Along with nearby
Castor, the trio form an attractive
right-triangle.
The second event is for early risers
because it takes place just as morning
twilight begins to brighten the sky. By
then the triangle has gotten bent out of
shape, and the gap between the Moon
and Pollux has shrunk to 1½°. For
observers on the West Coast, darkness
will linger just long enough for you to
Dusk, Oct 27 - 29
1 hour after sunset
NGULUM
PISCES
ARIES
Moon
Oct 27
Moon
Oct 28
Moon
Oct 29
be able to see the Moon form a perfectly
straight 6½°-long line with the two
bright Gemini stars as the configuration
approaches the zenith. The alignment is
most perfect shortly after 5 a.m. PDT.
TUESDAY, OCTOBER 10
This morning features what is arguably
October's most arresting conjunction,
and once again the Moon is a key
player. This time it shares the stage with
Regulus - the brightest star in Leo, the
Lion - and brilliant Venus, the reigning
Morning Star. The planet is nearing the
climax of its current morning apparition
as it approaches its greatest elongation
(46° west of the Sun), which occurs on
the 23rd. Of course, Venus will linger at
dawn far beyond that date. It'll remain
visible throughout winter and into
spring, when it finally succumbs to the
Sun's glare at the start of April.
On this morning, however, Venus is
Jupiter
an unmistakable beacon of magnitude
-4.6 and positioned a bit less than 2½°
from Regulus and about 5½° from the
Moon. Notice, too, that the lunar crescent
is adorned with a generous dose
of earthshine - sunlight that lands on
the Moon's surface after it has reflected
off our planet. This " twice-reflected
sunlight " (as S&T Contributing Editor
Chuck Wood dubbed it) makes it possible
for us to see the " unlit " portion of
the lunar disk.
Looking East
SATURDAY, OCTOBER 14
Today you have the rare chance of seeing
the new Moon - but only if you
take precautions. Such a sight is only
possible during a solar eclipse. Most
readers will get to enjoy at least some of
today's annular event, during which the
Moon passes in front of the Sun.
So, get out your eclipse glasses and
enjoy the show. (You can find complete
details starting on page 34.)
But wait . . . there's more! Two weeks
later (on the 28th), the Moon is full
and clips Earth's shadow, producing a
partial lunar eclipse. Turn to page 50 for
more on that event.
SATURDAY, OCTOBER 28
The month winds down with a nice
bit of symmetry as the Moon encounters
Jupiter for a second time. This
evening's event is an echo of the one
that occurred on the 1st. This time as
the Moon rises it's nearly full - only
hours after being exactly so. Full Moon
officially occurred late in the afternoon
at 4:24 p.m. EDT. This evening, the
Moon rises in deepening twilight about
20 minutes before Jupiter, and with
3½° separating them in the sky. Since
the Moon lies to Jupiter's west, the gap
between them will continue to slowly
narrow throughout the night. The two
are at their very closest at 2:13 a.m. EDT
on the morning of the 29th, when less
than 2½° separates them.
¢ Consulting Editor GARY SERONIK
keeps a close eye on the comings and
goings of the Moon and planets from
his home in southern British Columbia's
Okanagan Valley.
sk yand tele scope .o r g * OCTOBER 2023
47
24
EQUATOR
Neptune
Saturn
Oct 9
8h
Pollux
Castor GEMINI
6
Oct 3
TAURUS
Pleiades
Uranus
Oct 28 - 29
Jupiter
PISCES
AQUILA
AQUARIUS
OPHIUCHUS
LIBRA
Mars
ARIES
PEGASUS
HERCULES
Arcturus
+10°
VIRGO
0°
6h
4h
2h
0h
RIGHT ASCENSION
CYGNUS
22h
20h
18h
Vega
16h
BOÖTES
+30°
+20°
14h
DECLINATION
L
C
E
T
P
I
C
I

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Sky & Telescope - October 2023

Table of Contents for the Digital Edition of Sky & Telescope - October 2023