Sky & Telescope - August 2021 - 47

+30°
+40°
8h
6h
Castor
Pollux
GEMINI
Aug 3
30
0°
+10°
-10°
-20°
-30°
-40°
TAURUS
Procyon
Betelgeuse
ORION
Sirius
CANIS
MAJOR
10 am
8 am
6 am
Rigel
CETUS
ERIDANUS
Fomalhaut
LOCAL TIME OF TRANSIT
4 am
2 am
Aug
21-22
Midnight
Saturn
CAPRICORNUS
SAGITTARIUS
10 pm
17
Antares
SCORPIUS
8 pm
6 pm
HYDRA
4 pm
2 pm
27
EQUATOR
Neptune
Jupiter
15
4h
RIGHT ASCENSION
Pleiades
ARIES
Uranus
PEGASUS
PISCES
AQUARIUS
LIBRA
12
CORVUS
-10°
-20°
-30°
-40°
The Sun and planets are positioned for mid-August; 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.
are. For lucky observers in the southernmost
U.S., Mexico, and Central America,
the Moon actually eclipses Nunki.
The midpoint of the event (when the
lunar disk is closest to the star, or the
occultation is halfway through) occurs
at roughly 11:47 p.m. EDT.
FRIDAY, AUGUST 20
Step outside this evening as twilight
deepens and look towards the southeast
for a delightful naked-eye sight. There,
the Moon rises with Saturn positioned
some 4½° above it, and with Jupiter a
little better than 17° to their left, like
a shy stranger hanging around and
hoping for an invitation to the party.
(Don't feel bad for Jupiter, though - its
Dusk, Aug 20 -21
45 minutes after sunset
invitation arrives on the 22nd.) The
ringed planet is fresh from its opposition
night on the 2nd (see page 49 for
more) and glows brightly at magnitude
+0.3. And yet, by quite a margin,
Saturn is the faintest of the threesome,
so it'll be the last to show up as the sky
darkens. How soon after sundown will
you be able to spot it? Feel free to cheat
with binoculars. One advantage to
having the Moon nearby is you'll have
a handy reference point, which should
make fi nding Saturn in bright twilight
that much easier.
SUNDAY, AUGUST 22
Some astronomy enthusiasts cringe a bit
when they see the phrase " Blue Moon "
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.
CAPRICORNUS
Saturn
Moon
Aug 30
Jupiter
Moon
Aug 21
Looking Southeast
Moon
Aug 20
Moon
Aug 31
Aldebaran
TAURUS
Looking Southeast,
high in the sky
 Consulting Editor GARY SERONIK has
witnessed more Blue Moons than he
cares to count.
sk yandtelescope.org * AUGUST 2021
47
Dawn, Aug 29 - 31
45 minutes before sunrise
in print. Here at S&T, we perhaps cringe
a little bit harder. That's because in
1946 we inadvertently played a signifi -
cant role in establishing the modern
defi nition of the Blue Moon as the second
full Moon in a month that has two.
And no amount of cringing is going to
put that genie back into its bottle. However,
it's worth noting that the original
defi nition - as set out in the Maine
Farmers' Almanac - had the full Moon
as " blue " if it was the third one in a
season that has four. Not to pick on the
Farmers' Almanac, but that's convoluted
enough that some confusion is almost
inevitable. So, in honor of righting a
historical error, take a moment tonight
to enjoy a " classic " Blue Moon - the
third full Moon in a summer that has
four. You can read a lot more about the
subject at skyandtelescope.org/observing/what-is-a-blue-moon/.
This
full Moon actually occurs at
Pleiades
Moon
Aug 29
8:02 a.m. EDT on the morning of the
22nd. As it approaches this phase,
the Moon will be setting in the westsouthwest
alongside Jupiter. Indeed,
the gas giant will be just 4° right of the
lunar disk. As noted on page 49, Jupiter
reached opposition just two nights
earlier and presently shines brilliantly
at magnitude -2.9. So, if the allure of a
Blue Moon isn't quite enough to get you
out of bed early, perhaps this attractive
pairing will do the trick.
AQUILA
OPHIUCHUS
CYGNUS
HERCULES
Arcturus
VIRGO
Venus
0°
2h
0h
22h
20h
18h
Vega
16h
14h
BOÖTES
12h
+30°
+40°
LEO +20°
Mercury
Mars
DECLINATION
E
C
L
I
P
T I C

http://www.skyandtelescope.org/observing/what-is-a-blue-moon/ http://www.skyandtelescope.org/observing/what-is-a-blue-moon/ http://www.skyandtelescope.org

Sky & Telescope - August 2021

Table of Contents for the Digital Edition of Sky & Telescope - August 2021