Norfolk Astronomical Society
Jupiter's Moons
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NAS member Kent Blackwell took this digital photograph of Jupiter's moon Io emerging from transit about 7:50 PM EST on 01/28/2002 (01/29/2002 0:50 UT) . The dark spot on Jupiter's disk is the shadow of Io. This event was listed here on this page as Jan. 29
0:47 I.Tr.E.
1:28 I.Sh.E.
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Revised 8/25/2008
Discovered by Galileo in 1610, there are 4 moons of the planet Jupiter that are easily visible, even in binoculars if you can hold them steady enough. The moon's names are Io, Europa, Ganymede, and Callisto and are assigned Roman Numerals I, II, III, and IV in that order, designating their increasing distance out from the planet. The inner moon Io takes only 1.8 Earth days to orbit Jupiter, while the outermost Callisto takes 16.7 Earth days.
As these Galilean moons orbit, observers with telescopes at least 4-inches (100mm) in diameter can witness them cast shadows on the planet, pass in front of the planet, into the planet's shadow, and be blocked by the planet's disk. Such events take several hours.
Watching the motions of the moons of Jupiter can be quite entertaining and exciting as the observer retraces the footsteps of Galileo who saw their motions as a model solar system and used their motions to argue for support for the Copernican Theory that the Sun was indeed the center of our Solar System, not the Earth.
In 1676, Danish astronomer Olaf Roemer working at the time at the Royal Observatory in Paris discovered a predictable time difference in these moon events as the Earth moved around the Sun which led him to calculate for the first time the finite "speed of light". So get out and try to observe some of these events, and walk in the footsteps of astronomical discovery!
How To Read Event Notation
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Event | Definition |
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Eclipse | Moon passes through Planet's shadow. The beginning of these are marked by a Disappearance and the end by a Reappearance. |
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Occultation | Moon passes behind the disk of the planet. The beginning of these are marked by a Disappearance and the end by a Reappearance. |
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Shadow | Shadow of moon on the planet. The beginning of these are marked by an Ingress and the end by an Egress. |
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Transit | Moon passes in front of disk of planet. The beginning of these are marked by an Ingress and the end by an Egress. |
Notation: In the table below, times are given as Universal Time (UT). Subtract 5 hours to convert times to Eastern Standard Time (EST), 4 hours for Eastern Daylight Time (EDT).
I.Sh.I means the moon Io has begun (ingress) a shadow pass across the planet which appears as a black dot on the planet. During (Ec)lipse events the moon may take several minutes to (D)isappear/(R)eappear to/from invisibility, and may be out from the planet's disk when it does so.
The times given below are Universal Time (UT). To convert these times to local time (Eastern Standard Time or EST), subtract 5 hours. To convert these times to daylight time (Eastern Daylight Time or EDT), subtract 4 hours. If the answer will be negative, add 24 hours first then subtract 5 hours and the event takes place the day before.
The planet Jupiter is currently in the morning sky, and reaches opposition next June 5, 2007.
--- GLH
TIMES BELOW ARE UT
Satellites of Jupiter 2008
August
1 1 4.3 I.Ec.R 10 3 31.4 II.Ec.R 23 0 33.3 III.Ec.D
2 4.6 II.Tr.I 12 3 28.6 III.Tr.I 0 54.0 I.Tr.I
3 9.4 II.Sh.I 6 37.3 III.Sh.I 1 52.0 I.Sh.I
4 48.3 II.Tr.E 6 43.8 III.Tr.E 3 9.8 I.Tr.E
5 53.9 II.Sh.E 14 4 39.0 I.Tr.I 3 54.4 III.Ec.R
3 0 53.9 II.Ec.R 5 28.0 I.Sh.I 4 8.2 I.Sh.E
5 2 21.1 IV.Tr.I 6 55.0 I.Tr.E 24 1 17.5 I.Ec.R
2 37.6 III.Sh.I 15 1 47.6 I.Oc.D 3 58.0 II.Oc.D
3 19.4 III.Tr.E 4 53.8 I.Ec.R 26 0 12.6 II.Sh.I
5 56.1 III.Sh.E 6 40.4 II.Tr.I 0 55.9 II.Tr.E
6 4.7 IV.Tr.E 16 1 21.8 I.Tr.E 2 57.6 II.Sh.E
6 5 34.8 I.Oc.D 2 13.1 I.Sh.E 29 5 23.6 I.Oc.D
7 2 52.1 I.Tr.I 17 1 34.9 II.Oc.D 30 0 14.2 III.Oc.D
3 32.8 I.Sh.I 6 8.8 II.Ec.R 2 43.3 I.Tr.I
5 8.3 I.Tr.E 19 0 21.9 II.Sh.E 3 9.4 IV.Oc.D
5 49.3 I.Sh.E 21 6 26.9 I.Tr.I 3 30.7 III.Oc.R
8 2 59.0 I.Ec.R 22 2 24.8 IV.Sh.I 3 47.4 I.Sh.I
4 21.5 II.Tr.I 3 35.1 I.Oc.D 4 32.9 III.Ec.D
5 44.4 II.Sh.I 6 25.9 IV.Sh.E 4 58.9 I.Tr.E
7 5.2 II.Tr.E 31 3 12.6 I.Ec.R
Satellites of Jupiter 2008
September
1 0 32.2 I.Sh.E 9 3 3.3 II.Tr.I 20 0 4.5 II.Sh.E
2 0 36.6 II.Tr.I 10 2 0.6 III.Sh.E 22 2 46.4 I.Tr.I
2 48.3 II.Sh.I 11 3 19.7 II.Ec.R 4 2.4 I.Sh.I
3 20.1 II.Tr.E 14 3 32.3 I.Oc.D 23 53.1 I.Oc.D
5 33.5 II.Sh.E 15 0 53.4 I.Tr.I 23 3 27.2 I.Ec.R
4 0 42.5 II.Ec.R 2 7.0 I.Sh.I 23 29.9 I.Tr.E
6 3 53.4 III.Oc.D 3 8.7 I.Tr.E 24 0 46.9 I.Sh.E
4 33.7 I.Tr.I 4 22.8 I.Sh.E 1 28.6 III.Tr.I
7 1 41.1 I.Oc.D 16 1 31.8 I.Ec.R 2 29.7 IV.Tr.I
5 7.8 I.Ec.R 17 0 52.9 III.Tr.E 25 3 9.3 II.Oc.D
8 0 11.6 I.Sh.I 2 39.6 III.Sh.I 26 23 55.2 II.Sh.I
0 36.7 IV.Sh.E 18 0 36.3 II.Oc.D 27 0 4.4 II.Tr.E
1 17.0 I.Tr.E 2 41.2 II.Sh.E
2 27.5 I.Sh.E 23 59.4 III.Ec.R
30 1 46.9 I.Oc.D
Satellites of Jupiter 2008
October
1 0 26.6 I.Sh.I 9 1 46.9 I.Ec.R 20 0 20.3 II.Oc.D
1 24.1 I.Tr.E 23 6.5 I.Sh.E 21 23 51.5 II.Sh.E
2 42.2 I.Sh.E 11 0 19.1 IV.Tr.E 22 22 42.4 III.Sh.I
23 51.5 I.Ec.R 2 32.4 II.Tr.I 23 2 4.2 I.Oc.D
3 1 22.2 IV.Ec.D 23 20.1 III.Oc.D 2 7.7 III.Sh.E
23 55.4 II.Tr.I 12 2 39.4 III.Oc.R 23 26.8 I.Tr.I
4 2 31.9 II.Sh.I 13 3 5.5 II.Ec.R 24 0 41.5 I.Sh.I
2 39.5 II.Tr.E 15 3 0.4 I.Tr.I 1 42.1 I.Tr.E
5 0 34.9 III.Ec.D 16 0 7.1 I.Oc.D 25 0 6.8 I.Ec.R
6 0 28.8 II.Ec.R 23 44.8 I.Tr.E 28 23 41.4 II.Sh.I
8 1 4.3 I.Tr.I 17 1 1.8 I.Sh.E 23 59.1 II.Tr.E
2 22.0 I.Sh.I 19 23 51.3 IV.Ec.R 30 1 7.1 III.Tr.E
3 19.4 I.Tr.E 31 1 24.8 I.Tr.I
22 31.9 I.Oc.D
Satellites of Jupiter 2008
November
1 2 2.3 I.Ec.R 10 0 5.8 III.Ec.R 21 0 35.7 II.Oc.D
23 21.3 I.Sh.E 14 1 26.8 IV.Sh.E 22 21.9 IV.Oc.D
4 23 57.2 II.Tr.I 15 23 52.5 I.Tr.I 22 23 42.0 II.Sh.E
7 0 12.8 II.Ec.R 16 0 55.7 I.Sh.I 23 23 0.9 I.Oc.D
8 0 30.8 I.Oc.D 23 46.2 III.Oc.R 24 0 43.5 III.Oc.D
23 0.6 I.Sh.I 17 0 22.3 I.Ec.R 22 38.2 I.Tr.E
9 0 8.6 I.Tr.E 0 38.1 III.Ec.D 23 35.7 I.Sh.E
1 16.5 I.Sh.E 29 23 30.3 II.Sh.I
22 26.8 I.Ec.R 30 0 29.5 II.Tr.E