Sky and Telescope - November 2015 - 46

OBSERVING

Celestial Calendar

Jupiter's Moons
Nov 1
2
3

EAST

WEST

4
5
6

Callisto

7
8
9

Io

10
11
12
13
14
15

Europa

16

Ganymede

17
18
19
20
21

Action at Jupiter
Jupiter in November is still an earlymorning object and relatively small (33
to 35 arcseconds wide), but by the time
dawn begins it's high in the southeast,
nicely placed for telescopic observing
above tiny Mars and brilliant Venus.
Any telescope shows Jupiter's four
big Galilean moons. Binoculars usually
show two or three. Identify them using
the diagram at left.
All the interactions in October
between Jupiter and its satellites and
their shadows are tabulated on the facing page.
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;
Eastern Standard Time is UT minus 5.)

2:45, 12:41, 22:37; 20, 8:33, 18:28; 21, 4:24,
14:20; 22, 0:16, 10:12, 20:07; 23, 6:03,
15:59; 24, 1:55, 11:50, 21:46; 25, 7:42, 17:38;
26, 3:33, 13:29, 23:25; 27, 9:21, 19:16; 28,
5:12, 15:08; 29, 1:04, 10:59, 20:55; 30, 6:51,
16:47; 31, 2:43, 12:38, 22:34.
November 1, 8:30, 18:25; 2, 4:21, 14:17;
3, 0:13, 10:08, 20:04; 4, 6:00, 15:56; 5,
1:51, 11:47, 21:43; 6, 7:39, 17:34; 7, 3:30,
13:26, 23:22; 8, 9:17, 19:13; 9, 5:09, 15:05;
10, 1:00, 10:56, 20:52; 11, 6:48, 16:43; 12,
2:39, 12:35, 22:30; 13, 8:26, 18:22; 14,
4:18, 14:13; 15, 0:09, 10:05, 20:01; 16, 5:56,
15:52; 17, 1:48, 11:43, 21:39; 18, 7:35, 17:31;
19, 3:26, 13:22, 23:18; 20, 9:14, 19:09; 21,
5:05, 15:01; 22, 0:56, 10:52, 20:48; 23,
6:44, 16:39; 24, 2:35, 12:31, 22:26; 25,
8:22, 18:18; 26, 4:14, 14:09; 27, 0:05, 10:01,
19:56; 28, 5:52, 15:48; 29, 1:43, 11:39,
21:35; 30, 7:31, 17:26.

October 1, 7:47, 17:43; 2, 3:38, 13:34,
23:30; 3, 9:26, 19:22; 4, 5:17, 15:13; 5,
1:09, 11:05, 21:01; 6, 6:56, 16:52; 7, 2:48,
12:44, 22:39; 8, 8:35, 18:31; 9, 4:27, 14:23;
10, 0:18, 10:14, 20:10; 11, 6:06, 16:01; 12,
11:57, 11:53, 21:49; 13, 7:45, 17:40; 14, 3:36,
13:32, 23:28; 15, 9:23, 19:19; 16, 5:15, 15:11;
17, 1:07, 11:02, 20:58; 18, 6:54, 16:50; 19,

These times assume that the spot is
centered at System II longitude 230°.
Features on Jupiter appear closer to
the central meridian than to the limb
for 50 minutes before and after transiting. A light blue or green ﬁlter slightly
increases contrast and visibility of Jupiter's reddish and brownish markings.

22
23

The Coming Mars Apparition

24
25
26
27
28
29
30
Dec 1

The wavy lines represent Jupiter's four big satellites. The central
vertical band is Jupiter itself. Each gray or black horizontal band is
one day, from 0h (upper edge of band) to 24h UT (GMT). UT dates
are at left. Slide a paper's edge down to your date and time, and
read across to see the satellites' positions east or west of Jupiter.

46

November 2015 sky & telescope

Mars is still just a tiny dot in the
pre-dawn sky, telescopically swelling
from a pathetic 4″ to 5″ wide in October
and November. But get ready for bigger
things. That little spark, currently overwhelmed by Venus and Jupiter nearby,
is beginning its best apparition since
2005. Mars will spend next May and
June closer and larger than it has been
since when you were 10 years younger,
topping out at 18.6″. It will be at opposition on May 22nd and closest to Earth
on May 30th. If you've never seen Mars
well, this will be your chance.
Maybe. The downside is that Mars
spends those months far down near

the head of Scorpius at declination -21°
or -22°. The farther north you are, the
thicker the atmospheric seeing you'll
be looking through - and the more
important it will be to time your observing for late at night when Mars will be
highest. Mark your calendar.
As a bonus Saturn will be shining in
the same vicinity, to Mars's east.
Mars will come even closer in July
and August 2018, when it will reach
24.3″. That's nearly as big as it can ever
appear in its 15.8-year cycle of oppositions near and far. But it will then be in
southern Capricornus, a couple degrees
even farther south.
Sky and Telescope - November 2015

Table of Contents for the Digital Edition of Sky and Telescope - November 2015
