An African
and Asian
Annular
ON JUNE 21ST, the day after the June
solstice, the Moon will pass in front of
the Sun, producing an annular solar
eclipse. The Moon will be just six days
past apogee, with an apparent diameter
99.4% that of the Sun’s — too small
to cover the solar disk completely. So,
instead of a total eclipse, observers will
be treated to the dramatic sight of the
silhouetted Moon encircled by a narrow
annulus of sunlight.
The path of annularity varies from
21 to 85 kilometers wide and stretches
from central Africa to Taiwan before
departing solid ground for the Pacifi c
Ocean. At the track’s western end,
observers will witness the fi ery annulus
for up to 82 seconds, low in the eastern50 JUNE 2020 • SKY & TELESCOPENorther
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tesky shortly after sunrise. First contact
is at 3:46 UT, greatest eclipse occurs at
6:40 UT, and the Moon vacates the solar
disk at 9:34 UT. Visit Fred Espenak’s
website (https://is.gd/June21eclipse)
to fi nd viewing details for hundreds of
individual locations.
During a typical annular event, bril-
liant points of sunlight called Baily’s
Beads shi ne through valleys along the
edge of the Moon, fl ashing into view
moments before and after maximum
eclipse. But the fi t between Moon and
Sun this time is so tight that observ-
ers with safe eclipse glasses or prop-
erly fi ltered binoculars and telescopes
should get extended views of the Beads
as the jagged edge of the Moon breaks
the solar ring into numerous short
segments. Likewise, any bright
prominences along the Sun’s
limb that appear as the
Moon advances eastward
across the solar disk
should be easy to pho-
tograph and see in a
telescope, provided you
keep the blindingly
bright portions of the
Sun safely out of view.
I’ve witnessed two
annular eclipses and
saw brief glimpses of
prominences and Baily’s
Beads, but what really
made my jaw drop was see-
ing the Moon moving across
the Sun in real time.qAn annular solar eclipse takes place on June
21st. The central track, shown in red, crosses
Africa, the Arabian Peninsula, and southern
Asia.pFred Espenak captured this photograph of
the annular eclipse of February 16, 1999, when
the Moon covered 99.3% of the Sun’s disk.
This month’s eclipse is a very close match, with
the solar disk 99.4% obstructed.Action at Jupiter
AT THE START OF JUNE, Jupiter rises
just before midnight local daylight-sav-
ing time and transits the meridian dur-
ing morning twilight, when it should
be a fi ne sight in telescopes. On June
1st the planet gleams at magnitude –2.6
and presents a disk 45′′ in diameter.
Any scope shows the four big
Galilean moons, and binoculars usually
show at least two or three. In binocu-
lars, the moons are all but indistin-
guishable from one another. They orbit
Jupiter at different rates, changing posi-
tions 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 June interactions between
Jupiter and its satellites and their shad-
ows are tabulated on the facing page.
Find events timed for dawn twilight in
your time zone, when Jupiter is at its
highest.
Features on Jupiter appear closer to
the central meridian than to the limb
for 50 minutes before and after transit-
ing. 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.)
May 1: 6:39; 16:34 2 : 2:30; 12:26;
22:21 3 : 8:17; 18:13 4 : 4:08; 14:04;
23:59 5 : 9:55; 19:51 6 : 5:46; 15:42 7 :
1:38; 11:33; 21:29 8 : 7:25; 17:20 9 : 3:16;
13:12; 23:07 10 : 9:03; 18:58 11 : 4:54;
14:50 12 : 0:45; 10:41; 20:37 13 : 6:32;
16:28 14 : 2:23; 12:19; 22:15 15 : 8:10;
18:06 16 : 4:02; 13:57; 23:53 17 : 9:48;
19:44 18 : 5:40; 15:35 19 : 1:31; 11:27;
21:22 20 : 7:18; 17:13 21 : 3:09; 13:05;
23:00 22 : 8:56; 18:52 23 : 4:47; 14:43
24 : 0:38; 10:34; 20:30 25 : 6:25; 16:21
26 : 2:16; 12:12; 22:08 27 : 8:03; 17:59
28 : 3:54; 13:50; 23:46 29 : 9:41; 19:37
30 : 5:32; 15:28 31 : 1:24; 11:19; 21:15
June 1: 7:11; 17:06 2 : 3:02; 12:57;
22:53 3 : 8:49; 18:44 4 : 4:40; 14:35 5 :
0:31; 10:26; 20:22 6 : 6:18; 16:13 7 : 2:09;
12:04; 22:00 8 : 7:56; 17:51 9 : 3:47;
13:42; 23:38 10 : 9:34; 19:29 11 : 5:25;
15:20 12 : 1:16; 11:12; 21:07 13 : 7:03;JUNE 2020 OBSERVING
Celestial CalendarANNULAR ECLIPSE DIAGRAM: GREGG DINDERMAN / S&T, SOURCE: FRED ESPENAK