Discoveries in the Physics & Astronomy shop | Science, curiosities, and surprises
There’s a total solar eclipse coming across North America shortly. Weather permitting, make sure you take a little time to appreciate it!
With a little luck, we’ll be watching that little circle disappear, bit by bit, awaiting a little magic.
Copper-coated steel BBs, used in several different labs throughout physics and astronomy. Like many of the odds and ends we use for labs and demonstrations, these aren’t used as intended by the manufacturer. In this case, one can only imagine that off-label use is actually safer.
New semester, new classes, same old, same old around the shop. It’s not that we don’t notice the passage of time, just more that we’ve always got stuff to do. Things to sort out. Odd gizmos to tinker with.
Such as this wee little astronomy camera. (Much bigger than the camera portion of your phone, of course.) It’s a planetary camera, meaning it’s capable of a high framerate, even in low-light conditions. Unlike stars, which are effectively point sources, planets have visual size and even detail given reasonable magnification. Cool, right?
Of course, there’s this pesky but essential-for-life atmosphere in the way, and the visual wobbliness it produces – known as seeing – can make some photographs of Jupiter look like you’re peering at it from the bottom of a turbulent lake. Nicht so gut.
The simplest solution is to take a lot of pictures, sometimes compiled as a video, and select the very best ones, those moments in time when the seeing was perfect.
Of course, these cameras also work for other purposes, such as all-sky cameras to check for cloud cover at a remote location, or for meteor activity when you’d rather get some shuteye. Or, for kicks, to see one’s office through a fisheye lens.
“Observations of Variable Stars by the American Association of Variable Star Observers”
One would expect there’s no better-qualified group for the task.
We have several boxes of NASA press releases from the height of the space age, for the simple reason that it’s easier to pack things away than to sort and dispose of junk. None of them are worth much, really, but they can be entertaining. Take this, for example, a summary of the Ranger 4 launch. Not mentioned here, but interesting: Ranger 4 was the first US spacecraft to reach another solar system body.
By crashing into the Moon, as intended. You can read more in a brief summary by Leonard David, or by skimming Wikipedia.
Entertaining bits gleaned from the Space Activities Summary:
A surprise discovery on a hallway bulletin board at the Observatory: a push pin Big Dipper!
It’s good and charming and subtle, and we can forgive that this version has eight stars instead of the night sky’s seven. (Not counting the visual double of Mizar and Alcor where the handle kinks.) Someone did this on a whim, and now it’s hard to resist the idea of putting up others all over campus to see who notices.
Have a great semester break!
Making an ‘X’ across your telescope’s eyepiece is a handy thing, letting you mark the center instead of eyeballing it. There are all sorts of reasons you might appreciate that little bit of assistance, provided it doesn’t actively interfere with seeing things. So you use as fine a wire as you can. Which is going to break, of course, so keep some spares in the desk drawer.
How thin? This is AWG 53, all of 0.0007 inches thick (0.0178 mm). Enough to make even the finest human hair seem chunky in comparison.
An electronic buzzer buried inside a foam ball, on a long cable with a switch and handle at the end. Flick the switch, and a piercing 2,500 Hz signal begins. Whirled in a big circle around your own head, the tone persists. For everyone else in the room, it creates a cyclic Doppler shift, a repeating weeee-oooo, weeee-oooo that sticks in the brain even after it’s done, like when you see phosphene images behind your eyelids after catching a glimpse of something way too bright.
We can’t overstate the wonderful modifications to the original object, back in 2010, which added the cable and switch. Your bog-standard Doppler ball – available from several scientific apparatus purveyors – requires one to open up the ball, turn on the buzzer, then close it back up. Tossing it back and forth between students illustrates the concept.
Then, when you’ve had quite enough and just want it to stop, you have to pry it open and shut the whole thing off. (This vintage version, pre-mod, required full-on battery removal.) The Doppler ball: it teaches us all kinds of new lessons!
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.
And when did this charming item come into being? 1969, of course.
Both Physics and Astronomy courses do a lot of work with waves, and while light is one of the most important types for study, sound is exceptionally handy for demonstrations. There’s an immediacy, a feel, that can make sonic demos feel more intuitive.
We have a few of these about, metal bars with supports at the nodes of a standing wave, seated over a wooden box. The string goes where the bar doesn’t vibrate, and hence doesn’t dampen the sound, while the box helps it resonate louder. Ka-bong! They’re quite fun.
And, yes, Carl J. Ulrich of Minneapolis, Minnesota did some fine work here.