RASNZ logo

Royal Astronomical Society of New Zealand

Events of the Galilean Satellites for August 2009


Table of Events visible from New Zealand for August 2009.

Events of Jupiter's Galilean Satellites

Eclipses, occultations, transits and shadow transit of all four Galilean satellites will be occurring at regular intervals during August. A table of events visible during the month from NZ is included.

Eclipses occur when a satellite moves through the shadow of Jupiter. As it moves into the shadow the satellite will gradually fade from view and disappear. When it comes out of the shadow a faint spot of light will appear and gradually brighten.
Occultations occur when a satellite moves behind Jupiter as seen from the Earth. Hence during an occultation the satellite is hidden by the planet.
Transits occur when a satellite moves across the face of Jupiter as seen from the Earth.
Shadow transits occur when the shadow of the satellite cast by the Sun moves across the face of the planet

Occultations always start at the western limb of Jupiter and end at the east. Transits always start at the eastern limb of the planet and end at the west. In both cases the satellite will appear to "sink" into the bright limb of Jupiter at the ingress and gradually emerge from the limb of Jupiter at an egress.

In general eclipse events take place when the satellite is a small distance away from Jupiter as seen from the Earth. In 2009, Jupiter is at opposition on August 14. Before opposition eclipses occur to the east of the planet, after to the west. Near the date of opposition they will take place with the satellite very close to the planet. An extreme example of this occurs on August 14 when (2) Europa is eclipsed at the time of opposition with the result that both the disppearance into eclipse and the reappearance from eclipse are visible. They will occur at opposite sides of Jupiter and with Europa virtually in contact with the planet making observation difficult.

All these events can be observed through a small telescope. Note that when Jupiter is viewed through an undriven telescope its image will drift to the west. This enables the west side of the planet to be determined.

In the case of disappearances into eclipse (EcD) the satellite is likely to be visible as it fades for a minute or two after the predicted time. For reappearances (EcR) the satellite will start to emerge a minute or two before the predicted time.

At present the south pole of Jupiter is tilted only very slightly towards the Sun. As a result of the slight tilt all events appear to take almost in line with Jupiter's equator. From New Zealand Jupiter's north pole is the lower pole of the planet.

Table of Galilean Satellite events visible from New Zealand for August 2009

The table shows the times, in UT, of events visible from New Zealand for August. To convert times to NZST: for times greater than 12 hours UT, add 1 to the date and subtract 12 hours. Thus 14:38 UT on August 5, is 02:38 am NZST on August 6. For times less than 12, regard the time as pm NZST. This 10:20 UT on August 1 is 10:20 pm NZST.

Times of events are adapted from those given by Dave Herald's OCCULT 4 program.

Explanation:
Satellites: 1 = Io, 2 = Europa, 3 = Ganymede, 4 = Callisto.
EcD = Eclipse disappearance, EcR = Eclipse reappearance
OcD = Occultation disappearance, OcR = Occultation reappearance
TrI = Transit Ingress (start), TrE = Transit Egress (end)
ShI = Shadow transit start, ShE = Shadow Transit end.

Date Time UT,  Event Time UT,  Event Time UT,  Event Time UT,  Event
August 1 10:20, 1 ShI 10:41, 1 TrI 12:39, 1 ShE 12:59, 1 TrE
August 2 07:37, 1 EcD 08:11, 2 ShE 08:48, 2 TrE 10:13, 1 OcR
August 3 07:08, 1 ShE 07:25, 1 TrE    
August 5 14:38, 3 ShI 15:35, 3 TrI 18:17, 3 ShE 18:36, 2 ShI
August 5 cont. 19:03, 2 TrI      
August 6 17:46, 1 ShI 17:59, 1 TrI    
August 7 13:06, 2 EcD 15:02, 1 EcD 16:24, 2 OcR 17:31, 1 OcR
August 8 12:15, 1 ShI 12:25, 1 TrI 14:34, 1 ShE 14:43, 1 TrE
August 9 07:54, 2 ShI 08:10, 2 TrI 08:48, 3 OcR 09:31, 1 EcD
August 9 cont 10:45, 2 ShE 11:02, 2 TrE 11:57, 1 OcR  
August 10 06:43, 1 ShI 06:50, 1 TrI 09:02, 1 ShE 09:09, 1 TrE
August 11 06:23, 1 OcR      
August 12 18:39, 3 ShI 18:52, 3 TrI    
August 14 15:44, 2 EcD 16:57, 1 EcD 18:39, 2 EcR  
August 15 14:08, 1 TrI 14:10, 1 ShI 16:27, 1 TrE 16:29, 1 ShE
August 16 08:26, 3 OcD 10:23, 2 TrI 10:28, 2 ShI 11:23, 1 OcD
August 16 cont 12:15, 3 EcR 13:15, 2 TrE 13:20, 2 ShE 13:43, 1 EcR
August 17 08:34, 1 TrI 08:38, 1 ShI 09:03, 4 OcD 10:53, 1 TrE
August 17 cont 10:57, 1 ShE 14:24, 4 EcR    
August 18 07:58, 2 EcR 08:12, 1 EcR    
August 21 17:59, 2 OcD 18:40, 1 OcD    
August 22 15:53, 1 TrI 16:05, 1 ShI 18:11, 1 TrE 18:24, 1 ShE
August 23 11:42, 3 OcD 12:36, 2 TrI 13:03, 2 ShI 13:06, 1 OcD
August 23 cont 15:28, 2 TrE 15:38, 1 EcR 15:55, 2 ShE 16:15, 3 EcR
August 24 10:19, 1 TrI 10:34, 1 ShI 12:37, 1 TrE 12:52, 1 ShE
August 25 07:07, 2 OcD 07:32, 1 OcD 10:06, 1 EcR 10:36, 2 EcR
August 25 cont 14:58, 4 TrI 17:36, 4 ShI    
August 26 07:03, 1 TrE 07:21, 1 ShE    
August 29 17:37, 1 TrI 18:00, 1 ShI    
August 30 14:50, 1 OcD 14:50, 2 TrI 14:59, 3 OcD 15:38, 2 ShI
August 30 cont 17:32, 1 EcR 17:42, 2 TrE 18:30, 2 ShE  
August 31 12:03, 1 TrI 12:29, 1 ShI 14:22, 1 TrE 14:48, 1 ShE

Return to RASNZ home page