Discoveries in the Physics & Astronomy shop | Science, curiosities, and surprises
In 1963, one could purchase a Standard Astro-Dome with a 17′ inside diameter for the low, low price of $14,667. It must have been a worthwhile investment, because we’re still using it 60+ years later with no plans to update or replace it anytime soon.
Adjusted cost in 2023 dollars: $144,932.41.
When you need to keep things cold, you have options, depending on your temperature needs and what’s available. Carnot cycle refrigeration is handy, effective, and reversible when you need to supply heat (think a heat pump or household refrigerator). You can use the thermoelectric effect via a Peltier device, in which electric current through dissimilar materials causes heat energy to flow in one direction. Or you can just huck a bunch of cold stuff at your target and wait for thermal equilibrium.
Cool running water is remarkably effective in this case. Even colder: ice, though a slurry of ice and water is often faster because of the increased convection and heat transfer through the cold liquid. Sometimes that sizable dollop of energy required for phase transition is really handy! Salt/ice/water slurry gets you colder still, and it’s a great way to make ice cream in the backyard.
Colder still: dry ice, or solid carbon dioxide. (We’re now at the point where you really don’t want this stuff to get on your bare skin.) It has some limited cooling potential, as it sublimates directly to gas at atmospheric pressure, and so good contact and heat transfer can be slow. You can get it to liquid form – the correct cold temperature range and high pressure – which is how we make dry ice when we need it. If you need a suitable liquid for extra-cold chilling, you’re probably looking at liquid nitrogen.
At -77°C, it’s very cold. Your chilling rate becomes limited by the Leidenfrost effect – that thing where a layer of insulating gas forms between the hot and cold materials, thermally and spatially separating them. Same thing happens when you dip a wet finger into a vat of molten lead, or the slippery skitter of a water droplet across the surface of griddle heated just right for pancakes. But, still, cold. Very cold. We use it as a backup for a freezer that’s supposed to hang out at -80°C as long as the power’s on. The stuff inside can handle slightly “warmer” temperatures for the time it takes to repair a power outage.
If you need even colder? Really dedicated folks dial it up to 11 and use liquid helium. That’s a whopping -269°C, which sounds intense. Or, if you prefer, about 4 K. It gets used here at the University, just not in Physics. (Astronomers might study it, but at the safe distances used for telescopic observation.)
All of these extra-cold normally-gases need special handling and care, not only for the temperature concerns, but also for what happens when they warm up and expand and displace all of the breathable air around. (Bad.) We all have some sense of the too-much-carbon-dioxide/monoxide symptoms – sluggishness, blue lips, etc. – but those of us not trained as fighter pilots aren’t as readily aware of the distinct symptoms of too much nitrogen, not enough oxygen. If you are one of the lucky few, you get to undergo normobaric hypoxia training, which can lead to roughly 18 seconds earlier awareness of hypoxia, which sounds like an awful lot in a plane that can travel a third of kilometer in that period at Mach 1.
As for the the dangerous effects of breathing a sudden roomful of now-gaseous helium? We assume your final words are hilariously high-pitched.
Among the stacks and stacks of old records and books at the Observatory, we have a substantial text discussing best practices for astrophotography from…
1895. Sweet.
You may read a scanned version online if so inclined. Fun to note that, broadly speaking, the difficulties remain. With every improvement in technology comes an increased ability to explore and a growing expectation of quality, so there’s always opportunity to do better. From page 2:
“In order to appreciate the accuracy with which the mechanical adjustments
must be made, and the care with which they must be used, we should recollect
that in a telescope of sixteen feet focal length, a second of arc is rather less than
.001 of an inch, — a quantity quite invisible to the naked eye. We are required,
therefore, to keep a mass of metal weighing several hundred pounds following the
star with such accuracy, for perhaps an hour, that it shall not for any length of time
shift to one side of the other from its true position by this amount.“
No one expects an antique box of chocolate bars – a Boston-based brand which went out of business in 1981 – to contain those candies anymore. We reuse boxes all the time, and the key factors are size and durability. D-cell battery boxes are in relatively high demand, for example; good size and sturdy. Chocolates boxes, it seems, were once just right for storing lots of glass plates. This was so long ago, though, that the original use has become somewhat obscure. (The glass plates. No one’s confused about the eventual fate of the chocolate bars.) Now the boxes are more intriguing than their contents.
Idle thoughts bubble:
For those nights at the Observatory when the temperature drops and it gets fiercely cold, we have a little extra insulation from the weather. You might not be able to do much with these on, but you can’t do much when your fingers cramp up, either.
Suitably sized for holding a coffee or hot chocolate while appreciating how a clear, dry night can really bring out the stars.
It’s not uncommon for any place to collect things and never quite discard them, and it only grows worse when there’s no single person in charge of them. On some old shelves at the Observatory, we have no shortage of 19th-century astronomical observations from all around the world. A few select favorites recently spotted: Havana, Cuba; Hyderabad, India; Tachkent (now Tashkent), Uzbekistan.
Oldest so far spotted: Washington Astronomical Observations, 1848.
Part of the library collection since 1856. Wonder if the library knows? (We’ve put in a call to the proper folks, so no worries.)
“Library of University Lewisbg. Dec. 1856″
Neat!
We have a whole range of “old” telescopes at the Observatory which, depending on context, can mean state-of-the-art for the 1990s or the 1890s. This, most likely, is our oldest. It’s a lovely old brass refractor set on a fine wooden tripod, and with a properly-fitted eyepiece might work just fine. Not that we’re setting it outside anytime soon. It’s a showpiece!
How old is it? The acquisition date is currently unknown – probably recorded someplace in all of these stacks of papers – but certainly prior to 1886, because it wasn’t given to Bucknell University, but rather to the Lewisburg University, which is what this school was up until that point. That particular bit of information does confirm that it’s older than our big Clark refractor (1887) and our wee Ertel & Sohn transit telescope (1889).
“Presented *to the* LEWISBURG UNIVERSITY by Benj. Pike Jr. Optician 294 Broadway New York”
Second point of interest: Benjamin Pike, Jr. was located at 294 Broadway during 1843-44, as near we can tell. But the University at Lewisburg was founded in 1846. Benjamin Pike, Jr. lived from 1808 to 1864, giving us a reasonable last-possible year. So, um, wave your hands and call it circa [insert whatever]. It’s old, brass, and pretty cool.
It’s unclear who made the telescope, too. Pike (like his papa before him) was an optician by trade, and so would have known his way around lenses. None of the quickly-searchable web sources mentions telescopes, though, so maybe he just knew the right sort of gift for ol’ William Bucknell? It’s entirely possible another department on campus has a set of his award-winning surveyors’ tools. We’ve got theodolites in the closet – as one does – but none quite so vintage.
The-o-do-lite. It’s a word with some chew to it.
Cool. So very cool.
And not that we’d be willing to part with it, though it’s not like these don’t show up on the market from time to time. It’s a conversation piece!
Disassembling some old wooden equatorial wedges – a means of adapting an altitude-azimuth telescope for sidereal tracking at a specific latitude – and look what’s scribbled on the inside!
“PAT MULLIN RULES <– HE ALSO DROOLS”
Two different sets of handwriting. Appears to be two different ballpoint pens. Not clear if Pat had any input on any of this, or even who Pat is.
It should be noted that one can both rule and drool. Perhaps there isn’t a great deal of overlap in that Venn diagram, but they aren’t mutually exclusive.