Watch Jupiter during one of 18 eclipse opportunities between May and November 2008 from observing points near 111W longitude. View a Jovian satellite pop into or disappear from view during a Jovian eclipse emersion or immersion some distance from Jupiter's disk using binoculars or any class of telescope. Alternatively, using a planetary imaging camera, make a movie of a Jovian satellite eclipse event.
While single and rarer double satellite transit events one of the more popular Jovian observing pasttimes, another category of event - Jovian satellite eclipses are also interesting.
Jupiter from Earth on 9-23-2008 2:45UT just before Io eclipse reappear event Fig. 1 - Image courtesy of NASA/JPL Solar System Simulator
Eighteen eclipse opportunities were extracted from the RASC 2008 Observer's Handbook that apply to the author's observing point at 111W longitude, 41N latitude. Supplemental ephemeris data was gathered into three tables, below. Table 1 lists the events.
For events prior to August, beginner to advanced planetary imagers may want to consider making a movie of a Jovian satellite emersion and immersion events. Searching the web, there do not appear to be internet movies of such eclipse events, except for a movie made from a 2001 Cassini flyby of Io.
Amateurs who do make movies of the events listed in Table 1 are requested to forward a copy or a url link to this author for inclusion in the right-hand column of Table 1.
This sky party presentation cheat sheet was originally conceived as an observing list for school and scout parties. Kids in urban areas typically have binoculars and light-polluted urban skies, cannot see Jovian cloud detail, but can easily see the Jovian moons. Observing during an eclipse emersion event would allow them to see another active astronomical event, like a moving comet, instead of star hopping for static objects, like globular clusters. These events also provide a supplemental real world exercise when studying basic solar system orbits.
For school or scout star party support before August, this star party presentation cheat sheet and the observing opportunties are not suitable for children, as the observing opportunities are after midnight. After August, observing opportunities are before midnight and are better suited for school-aged children.
|Callisto IV||EcR||5/5/2008 4:12||5/5/2008 10:12||5/5/2008 9:33||none until event|
|Ganymede III||EcD||6/12/2008 2:45||6/12/2008 8:45||6/12/2008 8:10||none until event|
|Io I||EcD||6/12/2008 3:31||6/12/2008 9:31||6/12/2008 8:56||none until event|
|Io I||EcR||7/14/2008 2:19||7/14/2008 8:19||7/14/2008 7:45||none until event|
|Io I||EcR||7/22/2008 22:42||7/23/2008 4:42||7/23/2008 4:08||none until event|
|Callisto IV||EcR||7/27/2008 22:56||7/28/2008 4:56||7/28/2008 4:21||none until event|
|Io I||EcR||7/30/2008 0:36||7/30/2008 6:36||7/30/2008 6:01||none until event|
|Europa II||EcR||8/9/2008 21:32||8/10/2008 3:32||8/10/2008 2:57||none until event|
|Io I||EcR||8/14/2008 22:54||8/15/2008 4:54||8/15/2008 4:18||none until event|
|Europa II||EcR||8/17/2008 0:09||8/17/2008 6:09||8/17/2008 5:33||none until event|
|Ganymede III||EcD||8/29/2008 22:37||8/30/2008 4:37||8/30/2008 4:00||none until event|
|Io I||EcR||8/30/2008 21:13||8/31/2008 3:13||8/31/2008 2:36||none until event|
|Io I||EcR||9/6/2008 23:08||9/7/2008 5:08||9/7/2008 4:30||none until event|
|Europa II||EcR||9/10/2008 21:20||9/11/2008 3:20||9/11/2008 2:42||none until event|
|Io I||EcR||9/22/2008 21:27||9/23/2008 3:27||9/23/2008 2:47||none until event|
|Io I||EcR||10/8/2008 19:47||10/9/2008 1:47||10/9/2008 1:05||none until event|
|Europa II||EcR||10/12/2008 21:06||10/13/2008 3:06||10/13/2008 2:24||none until event|
|Io I||EcR||10/31/2008 20:02||11/1/2008 2:02||11/1/2008 1:17||none until event|
An orrey animation showing the relative motions of the Earth and Jupiter across six months of observing events is available. (1.4megs). All of the views in Table 1 also can be seen as a Microsoft PowerPoint slideshow. (3.2 megabytes).
|Callisto IV||5/5/2008 10:12||-41.1||21.9||150.6||19 35 56.11||-21 39 02.0|
|Ganymede III||6/12/2008 8:45||-23.5||26.3||167.6||19 29 18.94||-21 59 11.4|
|Io I||6/12/2008 9:31||-19.9||27.3||179.6||19 28 47.05||-22 00 06.2|
|Io I||7/14/2008 8:19||-26.7||24.7||197.4||19 12 33.90||-22 35 59.1|
|Io I||7/23/2008 4:42||-17.4||21.7||153||19 07 50.54||-22 45 03.4|
|Callisto IV||7/28/2008 4:56||-19.9||24.3||161.7||19 05 21.62||-22 49 47.5|
|Io I||7/30/2008 6:36||-29.3||25.8||189.4||19 04 19.98||-22 51 27.3|
|Europa II||8/10/2008 3:32||-10.9||22.2||155.2||18 59 43.84||-22 59 31.8|
|Io I||8/15/2008 4:54||-24.2||26.2||180.9||18 57 58.95||-23 02 26.3|
|Europa II||8/17/2008 6:09||-32.66||23.1||201.9||18 57 22.36||-23 03 31.4|
|Ganymede III||8/30/2008 4:37||-26.6||25.1||192.5||18 55 11.58||-23 07 45.4|
|Io I||8/31/2008 3:13||-13.7||25.7||172.1||18 54 32.95||-23 08 26.7|
|Io I||9/7/2008 5:08||-33.6||20.95||207.6||18 54 06.61||-23 09 32.7|
|Europa II||9/11/2008 3:20||-18.4||25.92||185.08||18 54 11.01||-23 09 46.4|
|Io I||9/23/2008 3:27||-23.8||23.91||198.3||18 55 39.16||-23 08 33.7|
|Io I||10/9/2008 1:47||-10.3||25.8||187.8||19 00 33.25||-23 02 39.6|
|Europa II||10/13/2008 3:06||-26.25||20.05||210.3||19 02 18.75||-23 00 20.0|
|Io I||11/1/2008 2:02||-19.9||20.3||210.4||19 12 47.24||-22 44 23.2|
|Satellite______||Time_UT________||One-way Light-time (mins)||Dist. Earth Jovian Moon (km)||Dist. Earth Jovian Moon (au)||Mag||S-O-T||S-O-T Type||S-T-O||T-S-O||hEcl-Lon Jmoon||Dist. JMoon (au)||hEcl-Lon Earth||Dist. Sun-Earth (au)|
|Callisto IV||5/5/2008 10:12||39.40||708679026||4.74||6.30||112.97||L||10.27||56.76||281.94||5.21||225.18||1.01|
|Ganymede III||6/12/2008 8:45||35.62||640632026||4.28||4.83||151.13||L||5.42||23.45||285.09||5.19||261.64||1.02|
|Io I||6/12/2008 9:31||35.58||639944506||4.28||5.34||151.16||L||5.42||23.42||285.09||5.19||261.67||1.02|
|Io I||7/14/2008 8:19||34.65||623223929||4.17||5.07||174.56||T||1.06||4.38||287.77||5.18||292.15||1.02|
|Io I||7/23/2008 4:42||34.83||626442315||4.19||5.19||165.03||T||2.90||12.08||288.51||5.18||300.59||1.02|
|Callisto IV||7/28/2008 4:56||35.09||631204428||4.22||6.70||159.66||T||3.90||16.44||288.93||5.18||305.38||1.02|
|Io I||7/30/2008 6:36||35.10||631413480||4.22||6.26||157.44||T||4.31||18.25||289.11||5.17||307.35||1.02|
|Europa II||8/10/2008 3:32||35.76||643198975||4.30||5.39||145.96||T||6.29||27.74||290.02||5.17||317.77||1.01|
|Io I||8/15/2008 4:54||36.12||649770060||4.34||5.22||140.71||T||7.12||32.17||290.45||5.17||322.62||1.01|
|Europa II||8/17/2008 6:09||36.30||653035825||4.37||5.42||138.59||T||7.44||33.97||290.62||5.17||324.59||1.01|
|Ganymede III||8/30/2008 4:37||37.54||675211701||4.51||4.93||125.53||T||9.15||45.32||291.70||5.17||337.02||1.01|
|Io I||8/31/2008 3:13||37.60||676389921||4.52||5.35||124.56||T||9.26||46.18||291.79||5.16||337.98||1.01|
|Io I||9/7/2008 5:08||38.37||690264814||4.61||5.41||117.59||T||9.96||52.45||292.39||5.16||344.84||1.01|
|Europa II||9/11/2008 3:20||38.84||698617151||4.67||5.58||113.80||T||10.28||55.93||292.72||5.16||348.65||1.01|
|Io I||9/23/2008 3:27||40.28||724507312||4.84||5.54||102.42||T||10.96||66.62||293.74||5.15||0.36||1.00|
|Io I||10/9/2008 1:47||42.30||760891444||5.09||5.64||87.89||T||11.18||80.94||295.09||5.15||16.03||1.00|
|Europa II||10/13/2008 3:06||42.83||770435816||5.15||5.79||84.28||T||11.12||84.60||295.43||5.15||20.03||1.00|
|Io I||11/1/2008 2:02||45.16||812347522||5.43||5.76||67.84||T||10.30||101.86||297.04||5.14||38.90||0.99|
|Satellite||Period (days)||Mean semi-major axis (km)||Period^2||Semi-major-axis^3|
Table 1 should be reproduced and distributed as a handout at public star parties when Jupiter first becomes visible at your observing point. Amateurs can use it as a reference list of future observing opportunities.
Table 1 lists 18 opportunties for observing Jovian eclipse events extracted from the 2008 RASC Handbook and particularlized for the United States Intermountain Region. The date of each eclipse event is provided at Mountain Daylight, Universal, and Heliocentric Time.
There are suprizingly few observable Jovian eclipse events throughout a year (other than Io) for any one geographic location. All events in Table 1 were chosen based on their visibility in the U.S. Intermountain Region near 111W longitude (Idaho, Utah, Arizona). Some of the events before July may be observable from the Central Mountain Time zone (Colorado). During and after September, some events may be observable from the Pacific Time zone (California) during twilight.
Tables 2 and 3 provides supplemental ephemeris data for each event. Heliocentric coordinates in Table 3 can be used by school children to construct a diagram of the relative positions of the Earth, Jupiter and the Sun using a ruler and protractor.
Before leaving for a night's observing, a watch should be synchronized to an accurate universal time source, such as the USNO Time Service Department. It is easy to miss a timed event if your observing watch is off by five or ten minutes.
Star party presenters can re-enforce observations at the eyepiece with the orrey animation and the data and simulated images in Table 1 in order to discuss the following principles:
Bogan, Larry. 2008. Phenomena of Jupiter's Galilean Satellites. In Royal Astronomical Society of Canada. 2008. RASC Observer's Handbook 2008. pp. 214-220. (Emphemeris of eclipse events).
Römer, O. 1677. A Demonstration concerning the Motion of Light, Communicated from Paris . . . Philosphical Transactions, vol. 12. In Bartusiak, M. 2004. Archives of the Universe: A Treasury of Astronomy's Historic Works of Discovery. Pantheon. New York. pp. 117-119. (Römer's 1676 experiment estimating the speed-of-light based on observed changes in the orbital periods of Jovian satellites).
Schlosser, W., Schmidt-Kaler, T. Milone, E.F. 1991. Challenges of Astronomy.. Springer-Verlag. 1991cahe.book.....S (Estimating the orbital period of Jovian satellites.)
NASA/JPL Solar System Simulator: This project has made use of the NASA/JPL Solar System Simulator to generate simulated images of the Jupiter.
NASA/JPL Horizons ephemeris application: This project has made use of the NASA/JPL Horizons Ephemeris generator to obtain Jovian ephemeris data included in Table 1.
John Walker's Home Planet planetarium software: This project has made use of John Walker's Home Planet desktop and his Your Sky to generate equal radius orrey images of the solar system.
This website contains amateur astronomer developed materials.
No copyright is asserted to any original content materials developed and included by this author in this document and the same are released to the public domain. No copyright is asserted as to any scientific fact recited herein or to any external content materials incorporated in this document.