Zenith: a live local-first fixed viewport planetarium

petee•1 day ago

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

smorgasborg•1 day ago

exactly. this takes me back to the low-tech beginnings

buescher•about 20 hours ago

When I put together my telescope setup I got a manual equatorial thinking I’d add a clock drive and my next telescope would have a go-to mount. It’s been about 20 years now.

dylan604•1 day ago

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.

leetrout•1 day ago

I _LOVE_ watching the moon transit my view port in my telescope. Love being reminded of this movement. The bigger planets are fun too.

smorgasborg•about 24 hours ago

> It would be interesting to allow the user to manually add location coords

shouldn't be hard. one difference is moving to a much higher/lower lat. to see the difference in angular speed. Where would you want to see?

dylan604•about 24 hours ago

32°

smorgasborg•about 24 hours ago

https://smorgasb.org/zenith32/

was quicker to hardcode one, then add the feature

smorgasborg•1 day ago

I'm the dev. happy to answer questions.

meta-meta•1 day ago

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?

smorgasborg•1 day ago

yes. the Field of View is the size of a grain of rice at arm's length. the total "movie" you see is like 2500 of those rice-grains, end to end (earlier in the explainer, it mentions the FoV size)

a-kgeorge•1 day ago

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.

toss1•1 day ago

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.

dylan604•1 day ago

It's even easier to see twice a day with sunrise and sunset!

smorgasborg•1 day ago

exactly. that's the only other time you can get that sense. (or moonrise/set)

toss1•about 23 hours ago

Yes, I've seen that too, and you can get the sensation.

But it is not nearly as vivid a sensation as the moon against a sharp edge of an alpine slope a couple km across a valley (vs all the way to the horizon).

The difference is on the scale of imagining being traveling in a railway car vs actually being in one. Once I saw it, it wasn't unlike being on a smooth Swiss rail just starting to pull out of the station...

dylan604•about 22 hours ago

Well, not everyone lives in mountains, so it was a pretty specific example. You could say the same thing about someone living in a city with tall buildings. You can just stand there and watch the moon climbing from behind them. There's a popular spot in my city that is a good distance from downtown so you see the skyline where photographers will line up to capture the moon rise behind downtown. You can tell the newbies by how casual they are about what they are doing vs the experienced ones that know once it starts it's over in a matter of minutes.

Zenith: a live local-first fixed viewport planetarium

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