Sky & Telescope - December 2018 - 49
Jupiter's Moons
skywatchers in the Southern Hemisphere. The radiant stays low, reaching approximately 30° in altitude as
it crosses the meridian, for viewers at
mid-southern latitudes. That limits the
number of visible meteors to about half
of what can be seen from the Northern
Hemisphere.
Make a Count
Despite being one of the more productive and reliable of the major meteor
showers, the Geminids remain a
somewhat under-reported event. This
may have something to do with the
shower's timing. For observers in colder,
northern climates, the temptation to go
(or stay) inside where it's warm can be
strong. This is too bad, as the Geminids
often outperform the more famous
summer Perseids.
But if you're willing to spend at least
one hour outside in December and like
to stay up late or get up very early, you
can do a scientific meteor count. Dress
for the weather (no meteor shower is
worth frostbite or even frostnip) and
make sure you have a comfortable
lounger or chair. As far as observing
equipment, you'll need an accurate
watch, a dim red light, pencils, and
paper; a voice recorder can help. You'll
need to follow a standardized method
for recording your sky conditions and
the actual number of meteors seen for
your records to be useful to the IMO.
For more detailed instructions, see
imo.net/visual/major.
If you're doing a formal count and
spot a light streak that doesn't seem
to emanate from the Geminid radiant, you might have caught an erratic
or a meteor associated with one of the
season's minor showers, such as the
Monocerotids, Sigma Hydrids, PuppidVelids, or even the Northern Taurids.
Dec 1
2
3
WEST
WEST
EAST
4
5
6
7
8
Europa
9
10
11
12
13
14
15
q The radiant for the Geminid meteor shower is located near Alpha Geminorum, more familiarly
known as Castor. To determine if a meteor is a Geminid, trace its path backward to its point of
origin. If you end up at a point well away from Castor, you've spotted either an erratic or a meteor
belonging to another winter shower.
16
Ganymede
Io
17
18
Geminid Meteor Shower
Dec 13, 9 pm
19
20
21
10°
Callisto
22
23
LY N X
24
GEMINI
Radiant
25
Castor
26
Pollux
27
28
29
CANIS
MINOR
Looking East
30
Procyon
31
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 0 h (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.
http://www.imo.net/visual/major
Sky & Telescope - December 2018
Table of Contents for the Digital Edition of Sky & Telescope - December 2018
Contents
Sky & Telescope - December 2018 - Cover1
Sky & Telescope - December 2018 - Cover2
Sky & Telescope - December 2018 - 1
Sky & Telescope - December 2018 - Contents
Sky & Telescope - December 2018 - 3
Sky & Telescope - December 2018 - 4
Sky & Telescope - December 2018 - 5
Sky & Telescope - December 2018 - 6
Sky & Telescope - December 2018 - 7
Sky & Telescope - December 2018 - 8
Sky & Telescope - December 2018 - 9
Sky & Telescope - December 2018 - 10
Sky & Telescope - December 2018 - 11
Sky & Telescope - December 2018 - 12
Sky & Telescope - December 2018 - 13
Sky & Telescope - December 2018 - 14
Sky & Telescope - December 2018 - 15
Sky & Telescope - December 2018 - 16
Sky & Telescope - December 2018 - 17
Sky & Telescope - December 2018 - 18
Sky & Telescope - December 2018 - 19
Sky & Telescope - December 2018 - 20
Sky & Telescope - December 2018 - 21
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Sky & Telescope - December 2018 - 24
Sky & Telescope - December 2018 - 25
Sky & Telescope - December 2018 - 26
Sky & Telescope - December 2018 - 27
Sky & Telescope - December 2018 - 28
Sky & Telescope - December 2018 - 29
Sky & Telescope - December 2018 - 30
Sky & Telescope - December 2018 - 31
Sky & Telescope - December 2018 - 32
Sky & Telescope - December 2018 - 33
Sky & Telescope - December 2018 - 34
Sky & Telescope - December 2018 - 35
Sky & Telescope - December 2018 - 36
Sky & Telescope - December 2018 - 37
Sky & Telescope - December 2018 - 38
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Sky & Telescope - December 2018 - 40
Sky & Telescope - December 2018 - 41
Sky & Telescope - December 2018 - 42
Sky & Telescope - December 2018 - 43
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Sky & Telescope - December 2018 - 49
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Sky & Telescope - December 2018 - 79
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Sky & Telescope - December 2018 - 81
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Sky & Telescope - December 2018 - 83
Sky & Telescope - December 2018 - 84
Sky & Telescope - December 2018 - Cover3
Sky & Telescope - December 2018 - Cover4
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