From the days before planetarium software was readily available, we have an intense glut of celestial globes, which show the positions of the stars and constellations on the night sky. Also the day sky, of course, but unless you’re watching a total solar eclipse they get lost in the bright blue light scattered by our atmosphere. They get little use except as office decorations.
We have two Earth globes – one is a giant, inflatable beach ball – which still get regular use in Astronomy classes. Unsurprisingly, visualizing the movement of an Earthbound observer on a tilted, rotating, orbiting planet around the sun isn’t always intuitive. Having a mini-Earth to look at helps immensely.
We also have a very nice lunar globe, which really should see more use. It’s highly detailed, including on the side of the moon that only a handful of humans have ever seen. (More craters, fewer mare.) If you dig maps, it’s a very cool map.
Scale 1 : 8,533,150.
And when did this charming item come into being? 1969, of course.
S’mores! Pretty much everyone likes s’mores, and they’re a great excuse to get outside and be social. And to make a cozy fire on an October evening.
Of course, if you also attempt to do this with physicists, the discussion is bound to turn to fluid turbulence and vortices and all of that…
In case you were wondering: there is a version of this which involves watching the fluid flow with lasers, because of course they have another way to play with lasers…
Considering that our course offerings cover the full range of classical mechanics, it should come as no surprise that we have many, many objects useful for demonstrating motion. Balls, cylinders, carts with low friction, blocks with high friction, carts which glide, carts which propel themselves, carts students can ride, etc. Also, just in case: a Jurassic Park-branded pickup truck.
It comes with a driver – currently leaning to their right, as if to call to someone on the passenger side of the vehicle – and a cage for the lion velociraptor. Complete with said velociraptor in the back.
For the most part, the light accumulation of dust, pollen, and other stuff on the objective lens of your telescope is a thing you live with and ignore. The damage you can do to the lens and its optical coatings is far more severe than the minor loss of image quality from tiny flecks. Known and accepted trade-off.
Here, however, we have a classic TeleVue Renaissance that’s still in good shape. Aside from the dust and dead spiders, anyway. Exact age is unclear, but we can roughly place it between TeleVue’s founding in 1977 and the construction of the “Halley’s Comet” models in 1985. Serial number 1100, for anyone keeping track at home. Even dust-covered, the optics appear good at a quick glance, and they have a reputation for remaining in good shape for a long time.
There’s a bit of chromatic aberration when you look closely, an issue which has been resolved in their current models. (Optics = hard.) The design type is called a Nagler-Petzval, which uses a pair of lens doublets to correct numerous distortions caused by refraction. Every design has its pros and cons; this one’s quite nice. Our version has – we think – an air-spaced doublet (two lenses utilizing different curvatures) as the objective, and a cemented doublet in the rear.
At least, that how the Halley’s Comet edition was made. The current optics update utilizes two air-spaced doublets – see the diagram for the NP101is – so it’s reassuring to see that the improvements are incremental. Good sign for the one we have.
Okay, the brass could’ve aged better, but it’s got character!
Needs polish.
Black on brass looks good.
Nice touch.
Even the knurled knobs on the focuser are brass. We don’t want to leave this for display, however. We want to see the stars!
Eesh.
That dust, though.
Speckly.
Yeah, definitely a problem. A cleaning is in order.
Can’t make it worse, right?
Not pictured: the dead spiders removed with air from a bulb blower. Dead spiders do not improve optical quality.
Red goo.
Here, we’re applying a coat of First Contact polymer cleaner, an expensive but effective treatment for safely removing gunk from precision optics. Comes in a wee bottle like it’s nail polish and smell like nail polish remover. Because it’s got acetone and other solvents in it.
Drying before removal.
Once it dries, that little tab lets us pull away the pink film with all of the dust and debris stuck in it. A good time to wander away from the stink of volatile solvents and get a cup of coffee.
Much improved.
And, well, that’s a substantial improvement.
Water spots. No dust.
It’s not perfect. The polymer is very good at removing particulates, but less so at water-soluble stuff. Once we evaluate this with a camera setup, we can see if a follow-up cleaning with deionized water is necessary.
Big improvement.
Problem there, of course, is that we run the risk of introducing tiny scratches in the process. Could be worthwhile if the effects are still visible, but we’re still erring on the “do a minimum of harm” side of things.
Despeckled.
Will it live up to its potential as an imaging ‘scope? Maybe. There’s a fair chance. If not, we’ll keep it around as a stylish yet usable throwback for visual observation. The best telescope, as they say, is the one you use.
