The first planetarium projector was unveiled 100 years ago
planetarium100.orgI was once the CTO for a small educational startup/company that was trying to make small (10ish people) portable planetariums. The goal was to install them in schools or other children/family friendly areas and serve the edu-tainment market.
It's actually quite interesting how many design and technical problems we had to solve to make the planetarium a "breathtaking" experience. Some interesting ones.
* Projection optics for a curved surface are a whole other ball game to a flat cinema screen. Pixel sizes change radically across the surface, and you have to use a combination of optics, clever encoding and film making to keep the perceived quality uniform across the entire surface.
* The gold standard for planetariums is that when each person looks at the "center" of the screen, no part of their visual field extends past the edge of the screen. That ensures the complete immersive experience. I ended up diving into biology and medicine literature to understand the size of the human visual field across age. At the same time, spent far too much time playing with the geometry of the planetarium.
* Air change. I found out that commercial spaces (concert halls or airplanes etc) change the entire air several times an hour. I then went about trying to min-max the number of air changes while keeping the exhaust fan noise levels imperceptible in this very small planetarium.
And many more. I also found interesting ideas. One publication claimed that if you played a loud sound, along with some sudden air flow changes just before starting your show, the audience would relax more. I wasn't able to implement or experimentally test this.
Special shoutout to the European Space Agency, who released many high quality full length planetarium shows under open licenses.
"* Air change. I found out that commercial spaces (concert halls or airplanes etc) change the entire air several times an hour. "
With good reason - spaces that don't are terribly uncomfortable within ten minutes.
It sound's a bit odd this is even notable.
This is the minimum standard for any new construction commercial/institutional building according to recent building codes in Ontario, and probably many other jurisdictions.
Maybe it's unusual for these building code standards to actually be enforced without special exemptions where the writer lives?
I was in a developing country where such things are rarely if ever enforced by law. Though, because many HVAC systems are imported, they automatically satisfy reasonable standards.
Our company had ethics enough to try and enforce such reasonable standards without any external pressure.
> Though, because many HVAC systems are imported, they automatically satisfy reasonable standards.
Not necessarily, because it's trivial to turn down HVAC systems to a smaller, code violating, number of air exchanges per hour.
I lived the first 25 years of my life without going to a planetarium. I even experienced VR before having been to one.
My first visit was a mind-blowing experience that felt akin to an acid trip. It wasn't just the night sky being projected but also a documentary that leveraged the projection medium. If you haven't been to one, I'd certainly recommend it.
I went to one with school as a kid, and this projector in the middle was the most science fiction looking thing I'd ever seen in real life
It probably was one like this: https://upload.wikimedia.org/wikipedia/commons/b/bb/ZeissPla...
BH Photo has a nice page on planetarium projection systems. They are eye-wateringly expensive.
https://www.bhphotovideo.com/explora/photography/features/pl...?
All I see on the Zeiss website for price is a "contact" button. How expensive are we talking about? :)
From the 2019 BH Photo article whose link I posted above:
"Cost has long been a factor in the acquisition of an OM projector. The Zeiss Model II cost $75,000 in 1926—more than $1 million in today’s dollars. Modern OM projectors can cost well over $2 million."
A 2011 Sky and Telescope article about Boston's Planetarium says, "Costing $2 million, the Zeiss Starmaster installed at Boston's Charles Hayden Planetarium uses fiber optics and its lens-covered 30-inch ball to project up to 9,100 stars."
https://skyandtelescope.org/astronomy-news/bostons-planetari...
I thought these were more ubiquitous. Yeah it's definitely worth checking out if you haven't been. The shows offered can be a bit on the cheesy side, what you really want to see there is a good tour of the night sky.
I love planetariums but it seems like most of the shows now are just films projects spherical screen. I’d really love to see one using an old-school star projector but it seems like they’re very hard to find now.
The word I love is "star ball". My local museum has one of these. They're apparently difficult for upkeep, since they've been produced such low volume. There's only a handful of specialists who travel around the country servicing them.
There's actually a Wikipedia page [0] (no doubt lovingly curated by beautiful nerds) that has a long list of planetariums with Zeiss star projectors.
But there's still the problem of finding shows where they are actually used...
0: https://en.wikipedia.org/wiki/Zeiss_projector#List_of_planet...
For the Pink Floyd fans: For the 50th anniversary of their album The Dark Side of the Moon, they're doing Planetarium shows of their album on multiple locations in Europe and North America: https://www.pinkfloyd.com/tdsotm50/planetarium-shows/
These are good traditions. I hope I’m alive to see the 100th anniversary of the first Pink Floyd laser light show.
I heard about it from previous generations, I’m not that old! Says me ;)
I'll just leave this here for the interested https://web.archive.org/web/20230408013446/https://www.plane... (archive link to not hug it to death)
It was very weird to see germany's president in the thumbnail.
It's pronounced Plane'arium. The 't' is silent.
So glad to see this cited.
At least three people weren’t happy about it! But it needed to be said :)