This field astro class was more packed than usual with opportunities for astro-science adventure. We succeeded in many of them, missed on some, and all-in-all had an exciting weekend. We had good support from the astronomy club - Kirk Bender, CSU East Bay Professor Chris Kitting, and Eric Messick brought their scopes and donated their efforts, and Shahram Tarani came Saturday and gave a demonstration of astrophotography. Friday evening began with a pasta dinner and telescope study of Jupiter and its moons. At 11:20am the Delta Aquarid radiant was rising, and we set out our sleeping bags and did a 40 minute meteor count. I passed out paper and instructions to all, and how to log the important data without breaking their attention visually on the sky. I'll reduce the data and post it when I get a chance. Next morning I cooked our traditional French Crepes breakfast, and then prepared for a busy day.
Chris got this fine photo of the Sagittarius and Scutum star fields, and captured the brightest meteor of our count. |
At the scopes on Friday night |
Saturday (crepes!) breakfast lecture on the comet impact layer and what we will be looking for, as well as passing out supplementary material on planetary science, and maps for the day. |
First project for Saturday was to examine the Black Point ash deposit near Wilson Creek. This deposit is due to a period of eruptions 13,600 to 13,300 years ago. This happened beneath Pleistocene Lake Russell, the much larger progenitor of today's Mono Lake. The Firestone etal (2007) paper which I passed out onsite proposed a Pleistocene comet impact 12,900 years ago which produced a layer of dark material rich in charcoal, magnetic particles, carbon spherules and nanodiamonds. We hoped therefore to find a dark layer just above the Black Point ash deposit, which itself is a layer a couple of feet thick. Allowing for inaccuracies in age dating, the impact layer might be below the Black Point layer, or even mixed within it. Our plan was to search for dark layers near the Black Point ash layer at a road cut near Mill Creek, and at Wilson Creek nearby.
The Black Point eruptions were clearly episodic. Austen examines a bizarre feature: wildly contorted ash deposits... |
...overlying flat ash deposits. How could this happen? |
A dark layer just above the BP complex, and an animal burrow. Could it be...? |
We examine the upper layer under a microscope. No charcoal or carbon spherules like those seen at other impact layer sites |
Jason takes a look; no evidence of magnetic particles in that upper layer either. |
So we do a half mile hike to Wilson creek and walk up the stream bed till we arrived at the Black Point ash layer, near the top of the stream cut here. |
Farther up, we find a slope giving access to the ash layer. |
The Black Point ash layer above silt layers. |
A slightly darker layer beneath the Black Point ash deposit at Wilson Creek. Did not look promising but we took a sample back to examine it.
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This darkish layer was above the Black Point ash, but at nearly 30cm thick it was over 10 times thicker than the comet impact layer at its discovery locations. We gathered more samples to examine microscopically back at camp. |
Chris discovered these interesting "vinegar nematodes" in the stream, and impromtu'd a micro-lecture for us. |
A shady cove along the stream bed on the walk back |
Our group on the Wilson Creek hike |
At Mono County Park neaby, my lecture on planetary science with emphasis on crustal dynamics, comparing Earth to the other planets, and California geologic history. |
Our group, just before the lecture on geothermal hot springs and comparison with possible Martian springs. |
me...holding a rock. Always a good prop! |
Chris delivers a micro-lecture on the sulfide-metabolizing archeo-bacteria which inhabit Buckeye Hot Spring near the outlet. Hot springs are the most likely place to find life on other planets, since they can supply energy by this unique chemistry independent of sunlight |
The give-away that this bio-coating on the rocks is sulfur-based is the yellow color |
After returning to camp, while there's still daylight, we examined our possible comet impact layer material with a good compound microscope. No carbon spherules or magnetic material, alas. But lots of very angular volcanic dust. |
Chris - in his admiral's cap, as befits a professor of marine biology - brought his 130mm Takahashi, excellent for showing off planets like Jupiter, which was closest to the Earth this month and bright in the southern skies. |
Kirk captured this shot of our class gathered around the scopes. Chris, Eric, and Kirk helped show students the variety of objects in our Galaxy, and I described stellar evolution with examples. |
Sunday 5am - time for the tough ones to get up for some Big Science. I've got the video equipment rigged to the 8" f/4. |
Sunday at dawn was our big graze. You can see the star at center. It moved up and to the right, grazing the dark side at top where I've labelled with a yellow arrow. Students monitored the timings from a separate TV screen. |
Chris Kitting also video-recorded the graze with his Sony camcorder on the Tak. |
My Sunday breakfast - fresh cut hash browns and veges, sauteed in olive oil and a rich vegetable base |
Our final venue - Panum Crater, the youngest volcano in mainland U.S. We met up with the ranger who gave us an interesting lecture on the geology of the crater. |
Esther snapped this shot of our class, climbing the central plug of Panum Crater |
"Tears of Pele" - droplets of molten glass which pull themselves into roughly spherical shape and solidify, all while still in the air after being tossed up by the volcano. They're fairly rare at Panum Crater. |
Look out, he's got a bomb! A "breadcrust bomb" as described by the ranger. Formed by rapidly cooling wad of glass tossed up by the volcano. The rapid cooling causes a surface of criss-crossing cracks much like fresh baked bread crust. |
After the Panum experience, I distribute the final exams, remind them there's lots of useful info in the instructor-prepared handouts, and wish everyone a smooth ride home. |
On the way home, I drove by the Yosemite fire, right across the Merced River |
Chris Kitting's video record of our graze is far superior to that done with the department's PC 164c, which suffered due to the strong dawn light. He'll be sending it to me to post here by the end of August. The graze timings are here.
Esther has posted a nice gallery of pictures from our class as well. Enjoy them here.
And finally - Esther made this fabulous quilt, inspired by the Pleistocene Impact... |
