FEBRUARY 2020 OBSERVING
Celestial Calendar
Mars and Moon Meet
50 FEBRUARY 2020 • SKY & TELESCOPE
MOVING ON TO MARS, the waning
crescent moon will occult the planet for
much of the continental United States,
Canada, and parts of Central America
during the pre-dawn hours on February
18th. For the East Coast the occultation
will take place after sunrise with the
Moon well-placed in the southern sky.
Because Mars will shine at magnitude
1.2 at the time, it should be visible in
a small telescope hovering along theMoon’s eastern (celestial direction)
edge. Locations farther west will see the
Moon cover the planet in twilight or
darkness and reappear along the dark
limb about 90 minutes later.
Unlike most stellar occultations,
in which a star suddenly disappears at
immersion and reappears at emersion,
Mars will gradually disappear and reap-
pear due to its much larger apparent size
of 5.2′′. If the seeing allows it, use high
magnifi cation to best appreciate Mars-
set during immersion and the especially
dramatic Mars-rise along the opposite
lunar limb at emersion. Skywatchers in
some parts of Central America will be
able to watch a grazing occultation with
the Red Planet fading and rebrightening
as it slides behind mountain peaks pro-
truding from the Moon’s southern limb.THAT’S PHI as in Phi (φ) Aquarii, a
4th-magnitude star that sits squarely
in Neptune’s path as the planet treks
eastward across Aquarius this month.
On February 10th the 8th-magnitude
planet practically brushes up against the
star, passing 2.3′ to its north with the
duo about 10° high in the southwestern
sky in late evening twilight. Steadily
held 10× binoculars will show the two
as a temporary, unequal double star. A
modest 6-inch scope will highlight the
strong color difference between blue
Neptune and its stellar companion, an
M-type red giant with a distinctively
warm hue.Neptune
Flies By Phi
Action at Jupiter
JUPITER REEMERGED from behind
the Sun in January, and it’s readily
observable at or before dawn in Febru-
ary. Although it rises while the sky is
still fully dark, you’re likely to get the
best telescopic views when it’s highest,
just before sunrise.
Any telescope 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 February interactions
between Jupiter and its satellites and
their shadows are tabulated on the
facing page. Find events timed shortly
before sunrise 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
Standard Time is UT minus 5 hours).
January 1: 1:10, 11:06, 21:02; 2:
6:57, 16:53; 3: 2:49, 12:45, 22:41; 4:
8:37, 18:32; 5: 4:28, 14:24; 6: 0:20,
10:16, 20:11; 7: 6:07, 16:03; 8: 1:59,
11:55, 21:51; 9: 7:46, 17:42; 10: 3:38,
13:34, 23:30; 11: 9:26, 19:21; 12: 5:17,
15:13; 13: 1:09, 11:05, 21:00; 14: 6:56,
16:52; 15: 2:48, 12:44, 22:40; 16: 8:35,
18:31; 17: 4:27, 14:23; 18: 0:19, 10:14,
20:10; 19: 6:06, 16:02; 20: 1:58, 11:53,
21:49; 21: 7:45, 17:41; 22: 3:37, 13:33,
23:28; 23: 9:24, 19:20; 24: 5:16, 15:12;
25: 1:07, 11:03, 20:59; 26: 6:55, 16:51;
27: 2:46, 12:42, 22:38; 28: 8:34, 18:30;
29: 4:25, 14:21; 30: 0:17, 10:13, 20:09;
31: 6:04, 16:00
February 1: 1:56, 11:52, 21:48; 2:
7:43, 17:39; 3: 3:35, 13:31, 23:27; 4:
9:22, 19:18; 5: 5:14, 15:10; 6: 1:06,
11:01, 20:57; 7: 6:53, 16:49; 8: 2:45,
12:40, 22:36; 9: 8:32, 18:28; 10: 4:24,Jan. UT Feb. UT
21 9:29 38:31
51 6:18 65:21
81 3:08 92:10
11 9:57 11 22:59
14 6:46 14 19:49
17 3:36 17 16:38
20 0:25 20 13:27
22 21:14 23 10:17
25 18:03 26 7:06
28 14:53 29 3:55
31 11:42
These geocentric predictions are from the
recent heliocentric elements Min. = JD
2445641.554 + 2.867324E, where E is any
integer. For a comparison-star chart and
more info, see skyandtelescope.com/algol.Minima of Algol
RONALD VAN DIJKtThe Moon will occult Mars (just seen
here) for most viewers in North America
on February 18th.