Jupiter Thrall

by Jane Houston Jones


The moon was beautiful, Saturn was spectacular, and Jupiter was magnificent tonight. The three performed a line dance on the ecliptic plane. We had our 4.1 f/5 inch AP Traveler out and the seeing was good enough to use our new 2.3 mm Lanthanum Eyepiece for a steady 265X moon look. Our 6 inch reflector was out for a while too, until a neighbor/teacher took it away to use at a school star party tomorrow night.

The moons Io and Europa were on one side of Jupiter this evening. As I write this, it is 09:00 UT on 11/8. That's 1:00 AM PST 11/8, and the Great Red Spot has been visible for a couple hours now. Watching it rotate into view, slowly spinning as it has for hundreds of years was mesmerizing. This was one of the best views of the Great Red Spot that I've had through a scope of my own. We spotted some white ovals trailing the GRS, too. We watched the entire transit of the Great Red Spot tonight. But I was in a mooning mood and concentrated on the four Galilean moons of Jupiter for some of the night.

I was amazed at the color and contrast of Io and Europa. These two moons have distinguishing differences you can spot when they are so close to each other. I'm new at this moon color business. The other night I got myself all mixed up by observing these moons with both reflector and refractor. So I am getting to know the moons by their color and size. Like everything else, practice makes perfect. This is Jupiter season, so I know I'll get lots of practice.

Io and Europa were round disks through the Traveler. No doubt about it, these were moon marbles. The color of Io was a ruddy red. Europa was further away from Jupiter and looked a little lighter and bluer red/orange to me, but still a pastel orangey-blue. I know Io is larger, but Europa appeared to be a tiny bit bigger and brighter to me tonight. In between Jupiter and Io was a star, TYC 1277-1299-1 - a mag 8.73 star. I mention it in case others saw it and thought it might be an inner moon. No way!

On the other side and out of view through my eyepiece stood lone Callisto. Callisto was big and dark and dull -- a blue-grey shade of moon. These three moons were joined at 12:21 (08:21 UT) by Ganymede. Appearing first as a little "bump" on the North Polar Region, it stood separate ten minutes later. Close to the planet, the color of Ganymede appeared orange next to the grey/blue color of the NPR.

There's more to observing Jupiter than Jupiter itself. I like to think about Galileo seeing these same moons on January 7, 1610 through his homemade telescope. Tonight I watched the emergence of Ganymede, just like in January of 1610 when Galileo observed this same fourth moon appear after seeing the three "stars" which moved the wrong way. His observations were bold discoveries. Tonight, for me they were just another great night out mooning.