Earthwalk Day 1250 (25 June 2025), 12,460 km: Big Bear Solar Observatory

Another leg done; I arrived today at Big Bear Solar Observatory on Big Bear Lake. This is an observatory built for study of the Sun, and it contains what was until 2019 the highest resolution solar telescope in the world (and is still the largest such telescope outside Hawaii and China).

I say it’s on Big Bear Lake, but it might be more accurate to say the main building is in Big Bear Lake, or at least pretty much surrounded by the lake. It’s built on the end of a causeway about 200 meters long extending from the northern lake shore. Putting the observatory in the lake helps cool the atmosphere near the building and reduces heat radiation waves that would disturb the path of light reaching the telescope.

The observatory was established in 1969 and formerly was operated by Caltech; since 1997 it has been run by the New Jersey Institute of Technology.

The sun’s been visible lately from Syracuse too. It’s presumably partly to blame for temperatures up to about 34°C (94°F) and heat index up to 39°C (102°F) yesterday and the day before. In Syracuse, that’s more than warm enough, and I curtailed my outdoor activities. So leg 47 ended a couple days later than it otherwise would have. Leg 48 is under way. Heading south, about 7 km covered so far.

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: 34.237°N, 116.867°W.