Earthwalk Day 1375 (28 October 2025), 13,938 km: Fred Lawrence Whipple Observatory

I reached another observatory today: The Fred Lawrence Whipple Observatory on the summit of Mount Hopkins. I covered the last 34 km on my bike today, having replaced the leaking inner tube over the weekend. The real world route was a lot flatter than the virtual climb up the mountain; I wouldn’t have done that on a bike, I don’t think.

The observatory was built originally in the 1960s and named in honor of astronomer Fred Whipple in 1981, and it includes the MMT Observatory with its 6.5 meter telescope. “MMT” used to stand for “Multiple Mirror Telescope”, presumably because when it was constructed in 1979 the practice of combining light from multiple primary mirrors was novel; these days there are a number of multiple mirror scopes on Earth and in space. It no longer stands for anything because in 1998 the six mirrors (equivalent to a 4.5 meter telescope) were removed to be replaced with a single 6.5 meter primary. That’s a pretty hefty mirror, but at the time there were about eight larger telescopes in the world, and now a dozen or so.

Having gotten here, the end of Leg 53, I’ve started to retrace my path down the mountain. I’m about 3 km from the observatory — that’s road distance. As the crow flies, I’m only about half a km away. There’s a lot of switchbacks.

A map showing my progress is here, a spreadsheet with progress detail is here, and a Google Earth KMZ file is in this Google Drive folder. Present coordinates: 31.676°N, 110.881°W.