A Short Great Night for Planets

by Randy Muller

It was only partly cloudy, and dry, so I decided to take a chance on a Saturday night, December 4 session at the Henry Grieb Observatory, the dark-sky and mile-high observing site of the Sacramento Valley Astronomical Society. I assumed there would be some snow, but I also knew that it hadn't snowed for at least a few days. I've never been up there during the winter for an observing session, and I was curious to see how it would be.

The drive up was uneventful and the traffic was light. I began seeing patches of snow at about 4000ft, and by the time I was driving into the observing area, snow was a few inches thick on the road. The tarmac was mostly clear, but I was surprised to see snow occupying parts of it.

I was also a little surprised to see Shneor Sherman, SVAS member and Davis TACo setting up his 18" dob - but I wasn't totally surprised. Given the cloudly conditions, the cold, the snow and ice on the tarmac, I grinned at him and asked him if he was crazy.

"As crazy as you are," he replied.

I set up my scope, casting an eye to the sky periodically. Clouds were occupying the western half of the sky, and seemed variable. There were both high and low clouds. I felt we would be lucky if the clouds remained where they were for the evening. Larry, who ground an absolutely exquisite 12" mirror and built a fine truss-tube dob around it, showed up a little later. At first, Larry wasn't sure if he was going to set up, but he went ahead and did it, as the clouds seemed to be stable in the west.

Before it got dark, I took a look at Jupiter, and noticed that the Great Red Spot Hollow was beginning to transit. I didn't see any color in the Red Spot itself, and I saw numerous belts, especially in the northern hemisphere. I only used 55x.

Callisto was just skimming the south pole. Io lay to the east and the other two moons lay to the west. It looked like Io might transit Jupiter in a short while, so I made a mental note to check later.

The clouds took this opportunity to cover the sky, although stars could be seen in gaps and even through the thin clouds. Throughout the short night, I hoped to get a clear view of Aquila in the west, to see the naked-eye nova, but it never cleared enough for me to be able to see it. During some clearer moments, I looked for a star of similar brightness to Delta Aquilae near Delta Aquilae, but I never saw anything there.

It was fairly cold, and ice was forming on the tarmac, but I never felt cold. The ice had two sources: Melting snow created a stream down the middle of the tarmac which froze, and heavy dew was freezing as we were observing. It was getting slippery in spots, and we had to be careful walking. There was no wind, and I had my Lassen cold weather gear on, which proved more than sufficient. In fact, I was actually colder at Lassen in July than I was at HGO in December, but that is mostly because I was ill prepared at Lassen in July.

In what seems to be a common autumn pattern in the Sierras, it was dewy at the beginning of the evening, but dried out within an hour. Shneor commented that it seemed warmer, and Steve, who had been doing some astrometry (measuring position angles and separations of selected double stars using a CCD camera) in his nearby observatory, commented that the temperature had risen 5 degrees in the last hour.

After the clouds cleared a little bit, we looked at Saturn, which was showing a retinue of moons swarming around it. In Shneor's 18", I could see and identify 5 moons: Dione, Enceladus, Titan, Tethys and Rhea. Titan showed a disk and was orange colored. I looked for, but could not see Mimas, which was very close to the edge of the ring. The seeing at this point prevented me from being able to see the Cassini Division.

I could see the part of the Crepe Ring in front of the planet, and the shadow of the planet on the ring. These features gave Saturn a dynamic 3-d look.

It appeared to be clearing a bit again, so I decided to try for some galaxies on the Andromeda/Pisces border. I started with M33, the Pinwheel Galaxy in Triangulum. These galaxies lie about 3 degrees northwest of M33, and include NGC 507 as its brightest member.

M33 showed as a large, featureless blur. As I was preparing to starhop to NGC 566, clouds covered the area. This was incredibly frustrating. The clouds were thin enough to let stars and planets shine through, but opaque enough to hide the dim galaxies I yearned for.

I took a look at Jupiter through Larry's scope, and was impressed with the detail I could see. Io was gone, and Callisto had moved further away from the South Pole. Jupiter's belts were showing a lot of detail. I decided to look for Io, so I scanned over to the south eastern rim of the planet and gasped when I saw Io transiting Jupiter's face. It looked like a bright yellowish-white spot, and I could actually see the terminator on the eastern side, as it contrasted nicely with the bright Jovian cloud-tops behind it.

It looked very 3-d: Like a tiny white marble in front of the chaotic and messy part of South Equatorial Belt following the Great Red Spot Hollow. Its bright whiteness also contrasted sharply with Jupiter's 'white' zones, which were distinctly tan by comparison.

"Wow! Io is transiting!" I shouted involuntarily. Larry was surprised and stepped up to the eyepiece as I described where it was.

"Oh yeah, so it is. I've never seen anything like that before!" he reported with the steely calm of one who tunes pipe organs for fun.

While waiting for this area to clear, I walked out on the snow. The snow reflected the starlight in a peculiar way, and provided an eerie experience as I seemed to be in a 'star spotlight' that followed me around. The snow directly below me was reflecting the most light, and it dimmed the further away it was from me.

This cloud cover seemed worse than the last, and after viewing some of his targets and testing a new eyepiece, Larry gave up and left. I waited a while, hoping it would clear in honor of Larry's telescope sacrifice, but it seemed to be staying about the same, so I gave up, too.

The drive home seemed a little odd, because I was wide awake and not tired at all. It was a short but great night for planets.

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