May 30, 2009: Titan's shadow

Albert Highe

I looked forward to seeing Titan's shadow on Saturn - an event I've never observed before. The Clear Sky Clock indicated it might be clear at Foothills Park in Palo Alto, where the PAS public star party was being held. I loaded the 13" f/4.5 grab-and-go into the van and left home around 7:30PM. Sure enough, the fog was coming in heavy over the local hills but the skies looked clearer further south.

Before leaving HWY 280 at Page Mill Road, I saw another cloud bank moving in from the East. I kept my fingers crossed that the window between clouds and fog would remain open until at least 10PM.

Initially, skies were clear at Foothills Park. Early visitors were treated to views of the Moon and Saturn before dark. However, by 9:30PM, fog and clouds began moving in. Saturn soon disappeared to the unaided eye. By 10PM, Saturn couldn't be found in the 50mm finder either. It was very dim in the main eyepiece. Most people packed up and left. By the time I left the lot at 10:30PM, even the Moon was fully obscured. No one saw the shadow transit.

However, on the way home, as I approached the Edgewood Road exit, the skies cleared overhead. I could see fog and clouds everywhere else. Would my luck hold? Yes. Skies were still clear when I arrived home.

Very little sky is visible from my driveway. Typically, seeing is also quite poor. By another stroke of luck, the Moon and Saturn were well-placed between the trees. The fog that had been streaming over the hills when I left home a few hours before had completely disappeared. I quickly pulled the 13" from the van and set up in the driveway. I plopped in the 7mm Nagler T6 (212X) and focused on the Moon. Uncharacteristically, seeing seemed pretty good. I slewed over to Saturn, and there was Titan's shadow - a minute ink spot. The shadow was barely visible with the 9mm Nagler T6 (165X), so I returned to the 7mm. Seeing was steady enough that I could see the shadow about 80% of the time. After 15 minutes, the shadow disappeared as seeing degraded. Fog was quickly drawing a veil across the sky. I packed up. Mission accomplished.

Albert