Astronomy Night, 7.9.2016

Mt. Tamalpais

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It can be very difficult to find dark skies in the Bay Area, but climbing high can certainly help. Mt. Tamalpais rises to about 2500 feet and the all-volunteer Friends of Mt. Tam runs an astronomy night program from April to November. While the mountain is too close to the bay to be free of light pollution, when the conditions are right, there’s still a lot to see.

The astronomy program promises a topical speaker and a night sky tour in the Cushing Memorial Amphitheater, with a ‘star party’ to follow in the parking lot where volunteers have set up their telescopes. When I arrived at Rock Springs parking area, the lot was already divided into an area for cars and an observation are for the telescopes. I got one of the last parking spots before people were redirected to the overflow lot.

sun setting behind trees
tamalpais sunset with boulder in foreground

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 the wide range of environments in our solar system and beyond. The slides took us on a tour of planets and moons that may satisfy habitability conditions. Of particular interest was Mars, which lost its magnetic field, allowing its atmosphere to be stripped away by solar activity; the mooons of gas giants that are imbued with energy thanks to tidal forces; and the fact that distant Pluto has an atmosphere and active glaciers of its own. Meanwhile, our probes and telescopes in space are gathering 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. Could this type of environment harbor life? We just don’t know. Dr. Cabrol has an easy manner of speaking and made the information very understandable. Not since the latest Cosmos series aired have I felt such a sense of wonder.

The sky darkened as Dr. Cabrol spoke, and when her presentation was complete, a volunteer gave a sky tour. Using a green laser, he pointed out notable objects in the sky and the direction in which we might find them. Afterward, the audience began to clear out of the amphitheater. I had my red headlamp in hand and used it to follow the path back toward the parking area. I chatted with another first-timer on the way, who had heard about the astronomy night through a friend of his. We talked about the presentation and then parted ways at the parking lot. I wasn’t headed straight for the telescopes. There was a lot of activity (and bright lights) as people got in their cars to leave, so I figured I’d try to get some night sky photos, then come back to the telescopes later.

I dashed across the road and followed the path to a hilltop. I felt I should try to get something in the foreground, so I set up 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 bright, but it was in the west, away from the direction I was shooting. I fired off a test exposure and was shocked to see the Milky Way was visible! For the next hour or so, I took as many shots with different settings as I could, planning to stack them later when I got home (stacking multiple exposures can help reduce noise and clarify details). As the moon got lower and lower, and a light layer of fog blanketed San Francisco, I was able to make out the cloudy ribbon of the Milky Way with the naked eye.

I met a guy up there who had just returned from Tahoe. He showed me his Milky Way shots, which were great, and I asked some questions about his equipment and settings. Another lady walking along the path stopped to see what I was doing and I couldn’t resist showing her some of the photos.

astronomy observing rock springs tamalpais
milky way above mt. tamalpais with hiker's headlamp

I would have stayed up there 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, let alone the Milky Way. It’s awesome to have this program relatively nearby and I can’t wait to return and refine my photography technique.