Sunday, August 28, 2011

Micrometeorite candidates

The kids and I took apart a defective hard drive yesterday, and I used one of the magnets (in a plastic bag, which I then inverted) to fish for micrometeorites in the soil near a downspout.  I found a few plausible candidates, as well as a bunch of surprisingly pretty microscopic ferrous dust.

Here is a particularly pretty area.  The pointer is pointing to a round micrometeorite candidate.  It's stuck to some probably earth-origin stuff--the hard drive magnet magnetized all the samples, so they stick together.  There is also a pretty piece of glass or crystal closer to the top edge.

I ended up preparing a slide with four candidates (one a bit dubious) mounted under a glass coverslip.  It's hard to grab pieces as they are very tiny--though big enough to see naked eye as a tiny dot--and stuck magnetically to other things.  In particular, I lost the round one in the first photo, as it just shot away when I tried to grab it with a toothpick (which looked like a big blunt log under the microscope).  Here's one that didn't get away.  It's about 60% of the size of the ball in the first picture.  You can't tell in the photo, but if you shine the light on this, it's very metallic--a nice silvery object.

I ended up perfecting a method for extracting them.  First, I use the toothpick to sweep the area around it clean, looking in the microscope most of the time.  It's confusing, since the miscroscope reverses the view, but eventually the brain gets used to it.  Then I wet the toothpick with acetone.  The micrometeorite candidate sticks to the toothpick.  I then transfer it to a clean piece of glass.  Because the acetone evaporates so quickly, it's easy to just wipe the toothpick on the glass and the micrometeorite drops off.  I lost two promising samples--especially that nice big round one in the first photo--before I got the above two.

From what I've read, rounded things that look like they were partly melted are good candidates.  Here is a less rounded item that ended up on the slide of the four that I saved.  I don't know how it got there, as I only intentionally transferred three to it, if memory saves.  Maybe it accidentally got carried there.  It looks too rough-edged to be a micrometeorite.  However, I've also read that they can avoid atmospheric melting by being small, so maybe rough-edged things count as candidates, too.  It, too, has a nice shine to it, though the photo doesn't show it.

If you try to view this with bright-field microscopy, of course you just get black silhouettes.  What I did is I taped a bright LED flashlight to the microscope, pointing at the sample, and then I took timed exposures, holding the camera to the eyepiece (sometimes with some sort of adapter to keep the camera in place).  For the second two photos, I found a way of adding more light.  I took the microscope outdoors, and then reflected sunlight onto the slide with a mirror (actually, a hard drive platter--they make lovely mirrors).

The photos were taken with point and shoot cameras hand-held to microscope eyepieces, with some loose-fitting adapters to make it easier. The first photo was with a Sony P100 through the 10X Huygens eyepiece that the microscope came with. The second and third photos were with a Canon G7 through a Rini 30mm telescope eyepiece, using my home-made telescope-to-microscope eyepiece adapter.

Update: I wish I knew how to better identify micrometeorites. The very round one may not be one--see this article.

Thursday, August 25, 2011

Paper craft sundial

Here are instructions for a paper craft sundial I built last night.  The hard part was doing the trigonometry for getting the gnomon to be at the right angle after folding--I hadn't done much trigonometry for a while, especially in regard to laying out a three dimensional object (the gnomon is wider at bottom than at the top).  With the script complete, construction takes about fifteen minutes.

Monday, August 22, 2011

Fix for balance issue on 70mm F/4.3 refractor

My son's 70mm F/4.3 refractor had too easy movement, and couldn't balance with a 32mm Plossl eyepiece (it balanced fine with a light Kellner).  We added a tension adjuster on one side.

The second photo shows the right altitude bearing.  The nut is superglued in place.  If it ever comes unglued, I'll glue something on top of it to keep it in place, or replace it with a threaded insert, or think of something else.  The nut actually was a locknut, but I cut out a lot of the locking plastic, so its locking action is very mild.

And the last photo shows the inside of the mount.  The black ring is a superglued fiberglass washer.  On the other side, under the knob (you can kind of see it in the first photo) there is a superglued washer made from milkjug plastic (rough side facing the wood) so the knob doesn't come undone.

Friday, August 19, 2011

Sundial completed

It's done now, and I made an Instructable with detailed instructions.

Now, can I persuade my kids' school to have it painted somewhere?

Monday, August 15, 2011

Working on sundial

I'm planning to draw a large analemmatic sundial with the kids, with chalk on the driveway. But that's not as much fun as writing a perl script to generate a pdf file with all of the dimensions. The beta version of the script is now running here. Source is also available, of course.
Update: Just executed it in sidewalk chalk. That's the best I can do in terms of permanence, since we rent our house from the University.

Friday, August 5, 2011

Another telescope instructable

And another one of my telescope instructables has been put on the home page of Instructables. This is my 8" F/4 travel scope.

Wednesday, August 3, 2011

Observing on the Gulf Islands

In July, I visited one of the Gulf Islands in British Columbia, where my parents have a sea-side cottage. I brought my airline-portable 8" F/4 scope. The usual curiosity from airport security about the eight pound wooden box in my backpack, but no problems (I just need to allot an extra five minutes).

From my parents' front porch, I looked at and showed them M13, M27, M31/32, M51, M57, NGC 457, the Double Cluster and Albireo. The views were excellent. M27 had a very nice brighter squarish middle, with wings sticking out. I think that's tied for my nicest view of M27 (I've had a good view of it through my 13", too). When looking at M31, I couldn't see M110, perhaps because the M31 area was (a) low in the sky, and (b) that was the direction of Vancouver. NGC 457 (Owl/E.T./Airplane) always pleases people. We also saw a meteor and several satellites.

Once my parents went in, I went after the North American Nebula (NGC 7000). I have never had much luck with it. I saw it in my 68mm refractor with an O-III filter in a past year from the same location, but it was a very faint fuzzy with no structure. This time, still with an O-III filter, it was better due to better aperture: the edges were defined, and I could pan around it with the approximately two degree view of the Rini 30mm in the scope. (I should consider putting in a 2" focuser and using an even wider eyepiece in it.) I kind of got an impression of a shape reminiscent of North America, too.

I had heard that one can see the North American Nebula naked-eye with a filter if the sky is dark, and so I stared at the sky through the O-III filter. And I think I did in fact see it. I think I could also see M13 naked-eye with averted vision (no filter of course). It was almost directly overhead, so that helped no doubt.

The next time we went to a peak in the middle of the island, where I did an unofficial star party. We had almost thirty people show up, unofficially invited by email. We started with Saturn at around 10:15 pm. The rings were sharply defined, though I was using a low magnification due to the scope being fast and there being wind. (I also discarded the light shield due to wind.) I thought that it would be dark by 10:15 pm, but I didn't reckon with northern summer. It was closer to 11 pm before it was nice and dark. However, the party went very well. I showed the same objects as I had shown my parents, plus the Lagoon and Swan nebulae.

I always like it when deep sky objects are naked-eye visible. Overall, on the island, I naked-eye bagged North American (if O-III is allowed for naked-eye; but a filter only blocks light!), M8, M13, M31 and the Double Cluster. Only North American and M13 were particularly special to see naked-eye. M8 is naked-eye from my home, and M31 and Double Cluster are naked-eye from my regular observing location. I think sometimes I can see M31 naked-eye from home, too, but it's hard with the streetlights to the north.

Tuesday, August 2, 2011

My smaller Dobsonian instructable

Looks like my smaller Dobsonian telescope instructable has been featured as an editor's choice and is on the front page of Instructables. Yay!

Monday, August 1, 2011

Instructables space contest

Instructables is running a space-related stuff contest with nice prizes. I posted photos of four of the projects I described in this blog, and I encourage any readers to post their own projects.