Day 85: Orbital Geometry


September 21

Distance: 12.9 | Ascent: 2930′ | Descent: 1950′

Mile marker: 1575.3

Lunch: J – chili and rice (B+), A – green bean orzo (A)

Dinner: J – Thanksgiving (B-), A – spaghetti mac (B)


Today was the solar equinox, right? It falls on either September 20th or 21st based on how the Earth’s orbit orbits. Our watches said that sunrise was at 6:46 am and sunset was 7:00 pm. If it’s the equinox, shouldn’t it be an even split? Twelve hours of both sun and dark? Or if not an even split, fourteen minutes seems too large a difference for the equinox.

This rambling thought launched into a long and sometimes playfully heated discussion about the Earth’s orbit and rotation. We even stopped to draw diagrams in the dirt of the trail with our poles. We talked about the axis and its gyration. Maybe that explains this uneven equinox. This also isn’t the first time we’ve talked about planetary orbits and celestial things. During the last full moon, we had a big discussion about how moon phases happen and would would happen if the moon orbited around the Earth faster or slower.

Our lives these days are dictated by the sun and daylight. The moon is also cool. We get why ancient peoples would be so curious about these things and come up with theories explaining seasons and moon phases. We know enough now to explain it from the orbital geometries, but visualizing in 3D is still challenging and gives us things to think about on trail.

Also, the trail was nice today. We enjoyed our hotel to its fullest extent, checking out at the last possible minute, and got a ride back to the trail from a trail angel we found online. She was proud to tell us all about the area and its geology as we drove out of town.

Back on trail, we had some climbing right away. We always climb out of cities. Just once, we’d love a city at the top of a hill. We had loaded up with food in town, so our packs were heavy. Jason is trying to eat as many calories as possible over the next stretch before we have our long carries through the Sierras where he’ll surely be at a massive calorie deficit.

Despite the heavy packs, we made good time and got spectacular views, including our first glimpse at the true High Sierras. We also got our last look at Lake Tahoe.


Leave a comment