I built Zenith: a live local-first fixed viewport planetarium

This is very cool! Will definitely project on the ceiling.

I am struggling a bit with this explanation though:

> ZenithTrack shows a strip of the sky, a thin ribbon, one rice-grain tall, about 2,500 rice-grains long.

What does it mean to say "one rice-grain tall"? Is that angular diameter at arm's length?

I did a show and tell for an elementary school class of my astronomy hobby with a tracking telescope and sunfilter. One of the best things happened accidentally when the tracking died, but the kids ended up really amazed by just how fast the sun was moving out of view, and getting to manually chase it; otherwise it would have been a cool but fairly boring view

This is an interesting concept. I also like the idea of projecting onto a ceiling of a room. It is always surprising the first time you try using an non-tracking telescope to see how fast the earth is turning. This gives you that without a telescope being necessary.

I block location requests, so it's just showing me the default location as Stonehenge. It would be interesting to allow the user to manually add location coords.

This is fantastic. I love how it makes Earth’s rotation feel immediate and visceral with zero equipment. The controls and overlays are really well thought out. It would be cool to have a search box to jump to a specific star or coordinate, even if most things in the ribbon are obscure.

Very cool!

You can do this with the naked eye in an area with tall sharp mountains such as the Alps, Rockies, Andes, etc. at times when the moon is low in the sky.

Move to a position where the moon is partially obscured by a mountain across the valley, and watch. It is surprisingly easy how little walking it can take to find a useful alignment. Then just stand and watch. The effect is amazing, even more powerful than watching it drift out of frame the telescope — it really shifts one's perspective to feeling how the earth moving.