Log, Nov 20, 2009

107 people. We had people everywhere last night, and no wonder. We have had so many washouts that we have built a huge backlog of folks wanting to get down to the Observatory. Luckily, the sky, and Jupiter in particular, put on a real show.

Jupiter has 4 large bright moons but when we first got there only two were visible unless you had very sharp eyes. Actually, Io and Ganymede could be seen if you could detect the subtle differences in their coloring and Jupiter. Shortly after opening, Io moved off the face of Jupiter and at least 80 people watched as it inched its way out towards Europa and even more distant Callisto.

Ganymede was actually a dual attraction. Ganymede's shadow moved ahead and slightly below the moon itself. What made the shadow very tricky to see was that the shadow blended in with the storm belts which straddle Jupiter's equator. About two hours after Io left the limb of Jupiter, Ganymede began to raise a dimple on Jupiter's limb. Over the next twenty minutes or so it finally moved far enough to become distinct from Jupiter.

We switched to a higher magnification and centered on Ganymede. Many people could make Ganymede out as a tiny disk rather than a point of light at this higher magnification.

Fall was largely a washout and it was brought home to Francine and I very vividly when we saw many things we think of as the early winter sky where the last really clear night was showing the last traces of the summer sky. From now until spring, Orion will dominate much of our viewing. We showed the Trapezium within M42 [Great Orion Nebula] for the first time this fall only to realize it will also be the first time this winter in a week's time.

We got to see Mars which has been absent from our Friday night skies for almost two years. Mars and the Earth take roughly two years for the two planets to align themselves on the same side of the Sun.

-Les Coleman

Leslie Coleman
Leslie Coleman
Entry Date:
Nov 20, 2009
Published Under:
Leslie Coleman's Log
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