Sep. 4th, 2017

mmcirvin: (Default)
 On Saturday I took my daughter to one of our favorite places to go, the Boston Museum of Science, and probably the highlight of the trip was that I finally got her to see a show at the Hayden Planetarium (not to be confused with New York's Hayden Planetarium--this one was funded by the same guy's charitable foundation). She'd refused to see these shows for years, initially out of fear that they might be too dark or an overwhelming experience, then probably just out of stubbornness.

This time she finally agreed, and I made sure to pick a certain specific show. Basically all museum planetariums these days have high-definition digital projection systems, and most of their shows are just a movie played on the dome. These shows can be spectacular and even impart some information, but they're not proper planetarium shows, to my mind. The one you want for your first visit usually has a name like "Your Sky Tonight" or "Wonders of the Night Sky", and it has a live lecturer who will show you what you can see this time of year if you go outside on a clear night. It does what a planetarium is supposed to do: train the general public to observe the sky for real.

And, best of all, if the planetarium has an old-school opto-mechanical projector, generally a hulking machine with a strange insectoid appearance, they'll haul it out.

I was kind of afraid these things were going extinct, and they may well be, but they're not dead yet. Boston's is actually relatively new, a Zeiss Starmaster, which seems to be their mid-range model (New York uses the top-end Universarium Model IX, a machine that I gather costs close to 4 million dollars). Instead of the classic "dumbbell" appearance, with two spheres of star projectors connected by a cage containing mobile projectors for the planets, this looks more like a single ovoid ball with the planets and such projected from separate units on the base--probably mechanically simpler in an age of computer control.

These analog projectors are more expensive and less flexible than digital projection systems--they can't send you flying through interplanetary or interstellar space--but for showing the starry sky as seen from Earth, they're still just better. Don't get me wrong, I'm a big fan of digital planetarium software, but the analog star images are much brighter and sharper than you get from a single pixel of the digital systems. At one point, the lecturer for the show we saw switched from the Zeiss to the digital projector so she could send us to Saturn (for a poignant bit including a short NASA video about the impending end of the Cassini mission). Before it hurled us through the solar system, the digital system started out displaying the same starscape the Zeiss had been showing, as seen from Massachusetts on an evening in early September, but it was striking how much fuzzier the picture suddenly got, with less black blacks. 

This guy has a stupendous collection of old planetarium projectors that he is apparently trying to sell. If you want one, I guess this is the place to go. When I was at the Thomas Jefferson High School for Science and Technology, I remember the school had its own planetarium (dating from its older days as plain old Thomas Jefferson High, I'm pretty sure) with a small projector resembling some of these--I suspect it might have been a Spitz.

Here's a Japanese company selling a projector that they claim can show over a million stars. I don't know how it works. They say they're working on other tech, like the ability to combine the analog projection with a digital image with some sort of masking to put them together seamlessly.

A few years ago I went to a show at the Albert Einstein Planetarium at the National Air and Space Museum in DC, but the show I saw was just the movie-on-a-dome type--I was disappointed to see that their grand old insectile Zeiss Model VI stayed retracted into its pit in the middle of the dome. I remember seeing that thing work when I was a kid and it was called the "Albert Einstein Spacearium". It'd be interesting to compare it to the Starmaster or Universarium to see how Zeiss's tech has evolved.

May 2025

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