Figure: A diagram of the orbits of Jupiter's Galilean moons

Caption: Click on the diagram of the orbits of the Galilean moons of Jupiter and print the pdf version.

Instructions for completing the diagram:

1. The orbits and Jupiter are approximately to-scale.
2. The two solid vertical parallel lines define the transit and occultation regions for the Galilean moons as seen from the Earth.
3. Label "To Earth" at the top of the dotted vertical line.
4. Label the top part of the vertical lines as "transit region".
5. Label the bottom part of the vertical lines as "occultation region".
6. To obtain the Jupiter elongation and phase angle (i.e., the angle between Earth and Sun subtended by Jupiter) for today, ????

   The dates are for Coordinated Universal Time (UTC or UT) (PST=UT-8 PDT=UT-7) and the values are for the date start (i.e., UT=0).

   Choose the closest values for the current time of day or linearly interpolate for an even better value for the current time.

   Note that if the elongation is east/west, the phase angle is measured east/west from the Earth direction to the Sun direction.

7. Draw a line right across the page through Jupiter in the direction of the Sun. Then draw two parallel lines that just touch the edge of Jupiter. Label the region on the Sun side between the two lines the shadow transit region. Label the other region between the two lines the eclipse. You will need a ruler protractor.

8. Label the phase angle and give its value and the date . Put the elongation (indicated as such) beside the label for the phase angle.