Sky & Telescope - August 2022 - 50

AUGUST 2022 OBSERVING
Celestial Calendar
Action at Jupiter
CASSIOPEIA
Andromeda
Galaxy
Double
Cluster
Perseid
radiant
ANDROMEDA
PERSEUS
TRIANGULUM
Capella
Looking Northeast at 11 p.m.
Perseids Versus the Moon
THIS IS AN OFF-YEAR for the annual
Perseid meteor shower as it peaks on
the night of August 12-13, just one day
after full Moon. Before you completely
give up hope, though, remember that
the display produces plenty of bright
meteors and many spectacular fireballs.
Moreover, the stream is broad, so we
can expect at least a few Perseids darting
about on clear nights from mid-July
through the end of August.
During the shower's peak under
moonless skies, 90 meteors per hour
streak across the sky from a radiant
in Perseus, below the familiar W of
Cassiopeia in the northeastern sky (see
the chart above). However, moonlight
will reduce that number by about half.
Although this year's peak occurs around
1 UT on August 13th (9 p.m. EDT on
the 12th), you'll likely spot more meteors
from 2 a.m. till dawn local daylightsaving
time on the 13th, when the
shower's radiant stands at its highest.
The Perseids are famous for outbursts,
in which the counts can briefly
double or even triple. Last year during
the small hours of August 14th, a day
after the predicted maximum, only
about 45 meteors per hour were anticipated.
Instead, skywatchers got a big
surprise, with more than two streaks
per minute. The reason? Earth ran
into an unexpectedly dense filament of
dust deposited by the shower's parent
50 AUGUST 2022 * SKY & TELESCOPE
The annual Perseid meteor shower reaches
maximum on the night of August 12-13 but
with reduced numbers due to light from the
nearly full Moon. The meteors will stream from
the radiant, which stands about 20° high at
nightfall but climbs to more than 60° by the
start of dawn, when you'll see the most activity.
comet, 109P/Swift-Tuttle. What will
happen this year? Moonlight or not, I'll
be checking and encourage you to do
the same.
Minima of Algol
Aug.
UT
3
6
8
11
14
17
20
23
26
28
31
4:33
1:21
22:10
18:59
15:47
12:36
9:25
6:13
3:02
23:50
0:39
These geocentric predictions are from the
recent heliocentric elements Min. = JD
2457360.307 + 2.867351E, where E is any
integer. They were derived by Roger W.
Sinnott from 15 photoelectric series in the
AAVSO database acquired during 2015-2020
by Wolfgang Vollmann, Gerard Samolyk, and
Ivan Sergey. For a comparison-star chart and
more info, see skyandtelescope.org/algol.
AUGUST IS A BIG MONTH for Jupiter.
On the 8th, it reaches the meridian
before the start of morning astronomical
twilight for the first time this apparition
for observers at 40° north. On that
morning, Jupiter will shine at magnitude
-2.7, present a disk 46″ across, and
attain an altitude of 52° just as twilight
begins. You may want to continue
observing Jupiter into twilight, however,
since the planet's pastel hues become
more apparent against a deep-blue
sky. The giant planet spends the entire
month in Cetus, near the border with
the zodiacal constellation Pisces. Jupiter
slips into Pisces on September 1st.
Any telescope reveals the four big
Galilean moons, and binoculars usually
show at least two or three. The moons
orbit Jupiter at different rates, changing
positions along an almost straight
line from our point of view on Earth.
Use the diagram on the facing page to
identify them by their relative positions
on any given date and time. All the
observable interactions between Jupiter
and its satellites and their shadows are
tabulated on the facing page.
Features on Jupiter appear closer to
the central meridian than to the limb
for 50 minutes before and after transiting.
Here are the times, in Universal
Time, when the Great Red Spot should
cross Jupiter's central meridian. The
dates, also in UT, are in bold. (Eastern
Daylight Time is UT minus 4 hours.)
July 1: 8:10, 18:05; 2: 4:01, 13:57,
23:52; 3: 9:48, 19:44; 4: 5:40, 15:35; 5:
1:31, 11:27, 21:22; 6: 7:18, 17:14; 7: 3:09,
13:05, 23:01; 8: 8:56, 18:52; 9: 4:48,
14:43; 10: 0:39, 10:35, 20:30; 11: 6:26,
16:22; 12: 2:17, 12:13, 22:09; 13: 8:04,
17:59; 14: 3:56, 13:51, 23:47; 15: 9:43,
19:38; 16: 5:34, 15:30; 17: 1:25, 11:21,
21:17; 18: 7:12, 17:08; 19: 3:03, 12:59,
22:55; 20: 8:50, 18:46; 21: 4:42, 14:37;
22: 0:33, 10:29, 20:24; 23: 6:20, 16:16;
24: 2:11, 12:07, 22:03; 25: 7:58, 17:54;
26: 3:49, 13:45, 23:41; 27: 9:36, 19:32;
28: 5:28, 15:23; 29: 1:19, 11:15, 21:10;
30: 7:06, 17:02; 31: 2:57, 12:53, 22:48
August 1: 8:47, 18:43; 2: 4:39, 14:34;
3: 0:30, 10:25, 20:21; 4: 6:17, 16:12; 5:
http://www.skyandtelescope.org/algol
Sky & Telescope - August 2022

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