13 January 2007

I was out at the NY Hall of Science today for my amateur radio license upgrade class and stopped off in the museum store to buy an ant farm. While they no longer have an astronomy program at the Hall they do have a couple of astronomy items in the store.

The first is a planetarium projector that needs some more investigating. I have seen it operating in a dimly lit area of the store and it throws a pattern of dots of light onto the wall but I didn’t study them to see if I could recognize any constellations. The stars seem to move very quickly and I don't know if there is a real time mode. I also would like to find out its limiting magnitude. I didn't get a manufacturer's name so can't research it on the Web until after my next class in two weeks.

The other product is a planisphere made from nested bowls. The bowls are probably about a foot across and nine inches deep. The bottom bowl has the celestial sphere painted on it and the dates of the year printed around its margin. The top bowl has an opaque horizon painted on one half with a transparent window for the sky above and the hours of the day around its rim. The nested bowls spin freely together to make it easy to adjust the planisphere to the current date and time. Having the stars painted on a bowl should remove most of the spatial distortion you get with flat planispheres. The plastic looks like it would be scratched if not handled with care. The planisphere is not as practical for taking into the field as a traditional flat planisphere due to its three dimensional form factor. It is the most expensive planisphere I have found ker-chinging the cash register to the tune of $65. I need to get a manufacturer name on this one also so I can point to a picture.