Sky & Telescope - July 2024 - 50

JULY 2024 OBSERVING
Celestial Calendar
α
July 31, 1 am
Circlet
AQUARIUS
Saturn
PISCES
δ
Delta
Aquariid
radiant
CAPRICORNUS
Fomalhaut
β
10°
Action at Jupiter
Looking Southeast
Southern Delta Aquariid Meteor
Shower Paves Way For Perseids
THE SOUTHERN DELTA AQUARIID
meteor shower shares summer's slowand-easy
vibe. Active from mid-July to
late August, this display is expected to
max out with around 25 medium-fast
meteors per hour on the night of July
30-31. The luminous streaks appear to
emanate from a radiant in southern
Aquarius, about 3° west of 3.3-magnitude
Delta (δ) Aquarii. That's 16° below
the celestial equator, which means
observers in the tropics and Southern
Hemisphere have the best view.
However, northern meteor watchers
will still see some activity, though at a
reduced rate.
Be on the lookout as early as 10
p.m. for earthgrazers - meteoroids that
strike the atmosphere at a very shallow
angle and take several seconds to completely
vaporize as they cross the sky.
The peak viewing time occurs from 11
p.m. until around 2 a.m. local daylight
time, when the waning crescent Moon
rises in Taurus.
One of the benefits of watching the
Southern Delta Aquariids is the chance
to also catch some early Perseids,
which are active at the same time. You
may want to tally meteors from both
showers to see which display comes
out ahead. They'll be easy to tell apart
- Perseids point back to Perseus in the
northeastern sky, while Aquariids point
back to Aquarius, in the south. As far as
which way to face, I'd say pick the direction
that's darkest and has the least
amount of light pollution.
Mercury Visits the Beehive
CONJUNCTIONS BETWEEN deep-sky objects and planets are common, but
it's unusual for a planet to pass directly in front of a galaxy, star cluster, or
nebula. On the evening of July 6th, skywatchers in the southern U.S. and the
tropics will find zero-magnitude Mercury in the northwestern quadrant of
the Beehive Cluster, M44, in Cancer. Look low in the northwestern sky about
an hour after sunset. You'll probably need binoculars or a telescope to battle
twilight and get a good view. Unfortunately, bright solar glow engulfs the duo
for observers in the northern half of the country.
50 JULY 2024 * SKY & TELESCOPE
NOW ENTERING THE THIRD month of
its current apparition, Jupiter is at last
becoming a rewarding telescopic sight.
On July 1st, it stands better than 15°
above the east-northeastern horizon
half an hour before sunrise. By month's
end that figure improves to nearly 40°.
On the 15th Jupiter shines at magnitude
-2.1 and presents a disk spanning
34.4″. From the perspective of observers
at mid-northern latitudes, this apparition
promises to be a fine one, with
the planet favorably positioned on the
northern reaches of the ecliptic in Taurus.
As July begins, Jupiter's declination
is +21°. It'll remain north of this mark
for a little less than just two years.
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.)
June 1: 4:50, 14:46; 2: 0:42, 10:38,
20:34; 3: 6:29, 16:25; 4: 2:21, 12:17,
22:13; 5: 8:08, 18:04; 6: 4:00, 13:56,
23:52; 7: 9:48, 19:43; 8: 5:39, 15:35; 9:
1:31, 11:27, 21:23; 10: 7:18, 17:14; 11:
3:10, 13:06, 23:02; 12: 8:57, 18:53; 13:
4:49, 14:45; 14: 0:41, 10:37, 20:32; 15:
6:28, 16:24; 16: 2:20, 12:16, 22:11; 17:
8:07, 18:03; 18: 3:59, 13:55, 23:51; 19:
9:46, 19:42; 20: 5:38, 15:34; 21: 1:30,
11:25, 21:21; 22: 7:17, 17:13; 23: 3:09,
13:04, 23:00; 24: 8:56, 18:52; 25: 4:48,
14:44; 26: 0:39, 10:35, 20:31; 27: 6:27,
16:23; 28: 2:18, 12:14, 22:10; 29: 8:06,
18:02; 30: 3:57, 13:53, 23:49
July 1: 9:46, 19:42; 2: 5:38, 15:34;
Sky & Telescope - July 2024

Table of Contents for the Digital Edition of Sky & Telescope - July 2024
