Projection of the image of the moon as seen through my 6″ Newtonian onto the sidewalk.
If you’re like me, you’ve had the “outreach itch” for a while now, especially when the Comet C/2020 F3 (NEOWISE) streaked across the Northern skies. But setting up a telescope and inviting strangers to look through your eyepiece is not an option these days.
So what’s a sidewalk astronomer to do? Do some sidewalk astronomy, of course! And I mean literal sidewalk astronomy. All you need is a bit of equipment:
- Telescope
- Camera, smart phone, or anything that has a sensor and a video output.
- An adapter to mount the device to your telescope. For my iPhone, I use this adapter.
- A video projector. The smaller (and more portable) the better. Most have the ability to “keystone”, which removes the geometric distortion.
- Something on which to mount the projector. We used an A-frame ladder, but a smaller projector might fit on a tripod.
Video projector mounted onto an A-frame ladder.
The idea here is to take the view in the telescope, image it with your video device, and project that onto the sidewalk (or a wall, or portable screen, etc). Now folks can see what you’re looking at from a safe distance.
A little bit of sidewalk chalk and you can even advertise the day before. Let all the dog walkers and kids in the neighborhood know that they can take a walk on the moon tonight!
While the moon was certainly the best “wow factor”, we were also able to clearly see Jupiter and its moons. Saturn was a bit more of a challenge, but that was mostly due to the seeing.
We were also surprised how early you can setup. I figured we’d have to wait until it was really dark, but just a little past sunset and you could quite easily see the projected image on the sidewalk.
This shows the whole setup. My Newtonian is to the left of the A-frame ladder. The iPhone is connected to the projector with a lightning-to-HDMI adapter.