Galileo’s T.O.E.S. – Phase 2

Galileo’s TOES II Certificate Coordinator:

Douglas Smith
6032 S. Nantac Rim Dr.
Tucson, Az 85706
(520) 396-3233


Galileo’s T.O.E.S. is a callenge to observe all of the interactions between Jupiter and its four Galilean Moons.  Each cycle sees many of those events, but not necessarily all of them.

But twice in its orbit around the Sun, we see the orbits of Jupiter’s Galilean Moons almost exactly edge-on.  This means in addition to the events with Jupiter, the moons have events with each other.  There are two types of event:  Occultations and Eclipses.  These events can occur between each pair of moons.  The goal is to observe all of these events

Note:  All of the events do not occur during every 6th-year apparition of Jupiter.

Note: Galileo’s T.O.E.S. is not a prerequisite for Phase II.

Since they are spaced a minimum of 6 years apart,we will be offering multiple certificates. 

  • In each 6th-year apparition we will be issuing a certificate for those who manage to observe all of theevents occurring during that apparition.
  • There will also be a “Complete” certificate for those who observe all of the possible events.  (Note: this could take 18 years…)

6th-Year Apparitions

I have reviewed data from the past 3 apparitions and also the next one (2021).  This is what I found:

Key:  E = Eclipse, O = Occultation, 1 = Io, 2 = Europa, 3 = Ganymede, 4 = Callisto

2021 2015 2009 2003
1 E 2 Yes Yes Yes
1 E 3 Yes Yes Yes
1 E 4 Yes
1 O 2 Yes Yes Yes
1 O 3 Yes Yes Yes
1 O 4 Yes
2 E 1 Yes Yes
2 E 3 Yes Yes
2 E 4 Yes
2 O 1 Yes Yes Yes
2 O 3 Yes Yes Yes
2 O 4 Yes Yes
3 E 1 Yes Yes Yes
3 E 2 Yes Yes Yes
3 E 4 Yes Yes
3 O 1 Yes Yes Yes Yes
3 O 2 Yes Yes
3 O 4 Yes Yes
4 E 1 Yes
4 E 2 Yes Yes
4 E 3 Yes Yes
4 O 1 Yes
4 O 2 Yes Yes
4 O 3 Yes Yes

Requirements and Rules

This certification is available to members of the Astronomical League, either through their local astronomical society or as members at large.  If you are not a member and would like to become one, check with your local astronomical society, search for a local society on the Astronomical League Website, or join as a member at large

For the “Complete”certificate:

You must complete all 24 possible observation events.  

You should document the event by logging this information for each event:

  • First moon name
  • Event type (occultation, eclipse)
  • Seccond moonname
  • Date (either Local or Universal Time)
  • Time (use the same: Local or Universal Time)
  • Latitiude and Longitude of the observation
  • Equipment used
  • Filters used (if used)
  • Magnification
  • Seeing and Transparency

For a 6th-Year Apparition certificate:

You must complete all of the possible event-types for that apparition.  For 2021, this is 13.  You can earn this certificate every six years.

Logging information is as outlined above.

This certification do not count as requirements for the Master Observer certification.

Submitting for Certification

This program has a certificate (only) for those who successfully complete all of the required observations. Once you have made the necessary observations, either send a copy of your log to the Galileo’s TOES Award Coordinator, or have it reviewed and approved by an officer of your local club. That officer should then send an email to the Galileo’s TOES Award Coordinator with the observer’s name, club, e-mail address, and mail address. Also send the name and email address of the person to whom the certificate should be sent.

Upon verification of your submission and of your active membership in the Astronomical League, your recognition (certificate, pin, etc.) will be sent to you or to the awards coordinator for your society, as you specified.  Your name will also appear in an upcoming issue of the Reflector magazine and in the Astronomical League’s on-line database.  Congratulations.  Good luck with your next observing challenge.

Galileo’s TOES II Certificate Coordinator:

Douglas Smith
6032 S. Nantac Rim Dr.
Tucson, Az 85706
(520) 396-3233
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