Friday, March 25, 2011

Hunting for meteorites

Inspired by stuff on the web (e.g., here), I went hunting for micrometeorites. I wrapped a magnet with plastic wrap, and ran it through the dirt under one of our house's downspouts. Apparently meteorites have high iron content so magnets capture them. There was some magnetic dust. I then transfered a couple of pieces of it to a microscope slide and had a look. I saw black chunks of stuff with transmitted light, unsurprisingly, but they became pretty and shiny when I shone a flashlight on them. The two largest ones had rough edges. Micrometeorites are supposed to be smoother due to their hot passage through the atmosphere. But moving the slide around, I cam on a smaller piece with smoother edges and interesting texture that matched what one would expect a meteorite to look like. There was some shiny bumpiness, some small pit-like spots and some interesting rod/wave like areas.

I tried to save the tiny piece for future observations. I tried to stick it to some sticky tape, but the goo made it very hard to observe under the microscope. So I ended up dissolving the goo with acetone to recover the piece. As a side-effect, the piece became cleaner and was brightly metallic under the microscope. Unfortunately, I eventually lost it. It was very small, about four or five times longer than wide, and the width was about that of a hair or maybe a touch more. I lost it when I tried to transfer it with the tip of a needle from a dirtier cover glass to a cleaner one, but somehow it just disappeared--I used a powerful loupe to try to find it, but couldn't. Oh well.

At least the kids got to see it. I don't know it was a meteorite, of course. Too bad I lost it before taking a picture.

Thursday, March 3, 2011

70mm refractor project just about finished

And we've almost finished the 70mm refractor.  I may still add some sort of sight for aiming it more effectively, though.

The tripod is made of cherry from a recalled crib that I picked up for scrap wood for free on Craigslist, together with some 1/2" Baltic birch plywood.  I glued two cherry slats side-by-side to form each leg.  The mount is a miniature Dobsonian mount.  The big round cutouts on the mount are to accommodate the oversize focusing knobs.  The azimuth bearing rides on PTFE pads and an old CD.  The altitude bearing uses PTFE pads and a plywood circle.

I had some trouble focusing a GSO 32mm Plossl in it--there wasn't enough focuser in-travel.  I suppose if I want to use that eyepiece with it, I can trim the top of the diagonal a little.

The moon

Here is a great zoomable image of the moon from NASA.