200 inch Hale Telescope, Palomar Mountains, California - May 30, 2026

200 inch Hale Telescope, Palomar Mountains, California - May 30, 2026

200 inch Hale Telescope, Palomar Mountains, California - May 30, 2026

I attended a docent development day at Palomar Observatory — an introduction to what it's like being a guide there, with the goal of recruiting more volunteers. About 30 of us took part, joined by several experienced docents who walked us through the tour route and shared how they approach guiding visitors.

The guided tours started in the '90s, long after my last visit. Before that, the only public access was a visitor gallery on the main floor. With the tour, you actually get to go inside the dome and visit all three floors of the observatory.

We had two special treats that day. The first was riding along at the dome level as it made a full rotation — you can see that in the video below. It was a remarkably smooth ride, with barely noticeable starts and stops, and surprisingly quiet for a 1,000-ton structure on the move.

The second highlight was a visit to the 48-inch (1.2-meter) Samuel Oschin Telescope. We toured the dome and telescope, then headed down to the plate room below — the space where photographic plates were examined after development. These thin glass plates were loaded into a holder and inserted into the telescope, but with an interesting twist: each plate was pressed into a spherical curve to match the mirror's curvature, ensuring consistent focus across the entire image. Several plates that didn't meet quality standards were on display on the light tables, giving us a real sense of the craftsmanship involved.

Videos

Palomar Mountains, California

200-inch (5.1-meter) Hale Telescope, riding the dome as it turns