Last night I did­n’t get to bed until 4 am. Along with a cou­ple hun­dred oth­er peo­ple, I hung out at the Chabot Obser­va­to­ry, watch­ing the Earth slide in between the Sun and the Moon. One of the Obser­va­to­ry’s tele­scopes was open, and sev­er­al peo­ple brought their own ‘scopes, some home­made. The view­pieces were big enough to allow me to take some pic­tures through the telescopes.

The focus is a bit off there, but you can see the craters and plains of the Moon’s sur­face, and at the low­er right cor­ner, you can see the sur­face start­ing to dark­en as the penum­bra of the Earth­’s shad­ow begins to cross it.

It’s astound­ing what you can do with just a tri­pod, a mid-range dig­i­tal cam­era, and a tele­pho­to exten­der. The tele­scope spins the image around, so the shad­ow in this image is at the upper left, instead.

Below the fold, more pho­tos of a late night, high above Oakland.

Here are a few of the enthu­si­asts, includ­ing one high school astron­o­my class, on a field trip the first day of school, and a bunch of ama­teur astronomers with their telescopes. 

Because of the size of the sun, the Earth blocks only some of it at first. That par­tial shad­ow (seen above the fold) is called the penum­bra. The total shad­ow, seen here, is called the umbra. The cur­va­ture of the shad­ow makes it pos­si­ble to cal­cu­late the rel­a­tive size of the earth and the moon, allow­ing ear­ly astronomers to esti­mate dis­tances between the Earth and the Moon.

Once the Moon enters the umbra, the eclipse is total. The Moon typ­i­cal­ly turns red dur­ing this phase, though the par­tic­u­lar shade of red varies from eclipse to eclipse. It varies because, as one per­son at Chabot put it, the red is the reflec­tion of every sun­set and sun­rise on Earth. Just as every sun­set is dif­fer­ent, every reflect­ed sun­set differs.

It was won­der­ful to see that there are so many peo­ple will­ing to stay up until 4 am to watch an event like this, and it was great to see Chabot work­ing so hard to edu­cate those peo­ple who showed up. A local TV news affil­i­ate was film­ing, and hop­ing to put togeth­er a pack­age for nation­al dis­tri­b­u­tion. I hope the peo­ple watch­ing at home enjoyed it as much as I did.