Recent content by Andy Resnick

Next up: Altered Tinguaite/Phonolite (QAPF field 11), Fen complex. Similar appearance as Fen 253. Blocky phenocrysts of cancrinite, likely as pseudomorphic altered nepheline. Phenocrysts of sanidine heavily altered (dusty appearance, perthic texture). Groundmass is disordered, consisting...

I'm glad I had a helpful suggestion, I hope I can continue to do so :) One critical point I am unclear on is what is meant by 'thin' in this context. Optical thickness? Density of free charges? Something else? The book I mentioned covers propagation/reflection from an ionized slab, which...

Plasma optics is quite specialized, I was still surprised to see no discussion in the 'standard' textbooks. The basic complication is that the plasma has free charges and currents, so the Maxwell equations are inhomogeneous. Perhaps a thin film allows you to make certain simplifying...

Next up: Altered Tinguaite/Phonolite (QAPF field 11), Fen complex. This rock has an appearance very similar to Fen 252. Trachytic groundmass of sanidine laths, aegerine needles, and small aggregates of anhedral granular mineral, likely paragonite replacing groundmass nepheline. Small...

Altered Phonolite (QAPF field 11), Fen complex. Groundmass primarily consists of trachtytic sanidine laths and aggregates of anhedral grains of a mineral, likely cancrinite replacing groundmass nepheline. In addition, minor amounts of aegirine needles, and opaques are present. Blocky...

The sapcicle grew overnight:

At higher magnifications, you can use targets designed for electron microscopy (that's what I use), for example: https://www.tedpella.com/calibration_html/MRS-3_Magnification_Calibration.aspx https://www.tedpella.com/Calibration_html/MRS-6_Magnification_Reference_Standard.aspx

Took this a few weeks ago, forgot to share. I've forgotten the camera settings (400mm @f/4 lens, tho...): Jupiter (visible as a tiny dot in the lower right) was at closest approach to the moon; this is a single shot @ 400mm. The surprising thing (to me) is that both the moon and jupiter are...

Pine tree sap icicle (sap stalactite?) [Edit] Up close, it really looks like an icicle-icicle:

Thumbs-up for the photo, thumbs-down for the snow :)

Had a few clear nights during the past week, here's M44 (Beehive cluster/Praesepe): Definitely happy with the outcome, especially the jewel-toned stars. Astrometry.net picked up 6 galaxies, but there are another half-dozen that it missed (for example, the imaginatively named Z 89-66, 2MFGC...

Next sample: Tinguaite. Altered phonolite (QAPF field 11), Fen complex. Trachytic groundmass of sanidine laths, aegerine needles, and small aggregates of anhedral granular mineral, likely muscovite/paragonite secondary to groundmass nepheline. Small phenocrysts of biotite, large...

If it wasn't 1) during the workweek and 2) effing freezing cold, I would probably give it a try- thanks for the maps!

A couple of years ago, one of my Physics I students was a graduate of US sniper school- he knew that the Coriolis force had to be corrected for when long-distance shooting, but (prior to class discussion) didn't understand why or what.

https://apnews.com/article/meteor-cleveland-fireball-astronomy-89d1cd3e060774ff897512cb811710d7 Made for interesting discussions in class today! Nearly everyone heard it, hardly anyone knew what caused it.