Astronomy Night on Mt. Tam

It can be challenging to find dark skies in the Bay Area, but climbing high can certainly help. Mt. Tamalpais rises to about 2,500 feet and while it’s too close to the bay to be free of light pollution, there’s still a lot to see when the conditions are right.

The all-volunteer Mt. Tam Astronomy Programs organization gives everyone an opportunity to observe the night sky from Marin’s iconic mountain, which normally closes after sunset. Each lecture is accompanied by a night sky tour, with telescope viewing afterward (in cooperation with the San Francisco Amateur Astronomers society).

I wanted to see what this was all about, and, if possible, take some night photos as well.

On the night I chose to attend, Dr. Nathalie Cabrol (Director, Carl Sagan Center, SETI Institute) gave a presentation on “Habitability and Life Beyond Earth.” She talked about the conditions for life and how those match up with the wide range of environments in our solar system and beyond. Her slides took us on a tour of planets and moons that may satisfy habitability conditions.

Of particular interest was Mars, which long ago lost its magnetic field, allowing its atmosphere to be stripped away by solar activity; the moons of gas giants that are imbued with energy thanks to tidal forces; and the fact that even distant Pluto has an atmosphere and active glaciers of its own. Our probes and telescopes in space continue to gather surprising information about other worlds – data that will be used by powerful computers to model environments and permutations of life.

The presentation highlighted just how much we have yet to learn. For example, Jupiter’s moon Titan has a methane (rather than water) cycle, complete with lakes. If this type of environment could harbor life, we don’t know it yet, but the possibilities are exciting.

By the time Dr. Cabrol’s presentation was complete, the sky had darkened considerably, and a volunteer used a green laser to point out notable objects in the sky and the direction in which we might find them. It was humbling to sit there in the dark with the rest of the audience.

When I returned to the parking area, I dashed across the road and followed the path to a hilltop. I set up my camera and tripod near a rocky outcrop. The light pollution was pretty strong, but a lot of stars were still visible, especially in the direction of the ocean. The moon was also bright, but it was setting in the west, away from the direction I was shooting.

I fired off a test exposure and was genuinely surprised to see the cloudy band of the Milky Way in the frame! This was my first time capturing it and I could barely contain my excitement. For the next hour or so, I took as many shots with different settings as I could. I wanted to find out which settings worked best for my setup and take enough images to stack them later (a post-production method that helps reduce noise and clarify details). As the moon got lower and lower, and a light layer of fog blanketed San Francisco, I was just able to make out the Milky Way with the naked eye.

I would have stayed longer, but I wanted to check out the telescopes before the volunteers cleared out. One volunteer showed me Saturn and I was impressed by the crispness of the image in the eyepiece. I could clearly see the rings. It’s a small thing, but to be actually looking at the real object is completely different from seeing photos secondhand. Your brain already knows, rationally, that Saturn exists – yet you really “get it” more when you see it with your own eyes. Another volunteer showed me the ‘False Comet‘ – a feature composed of several elements. The bright cluster of stars in the center is estimated to be 6,000 light years away.

Before I attended the astronomy night, I had no idea if I’d be able to see much in the Bay Area’s night skies, let alone the Milky Way. The Mt. Tam Astronomy Programs are a great resource for the community and I highly recommend it as a way to see our home from a new perspective.