I’ve been noodling on a new app idea — nothing revolutionary, just something quietly beautiful: understanding the sun.
Not just sunrise and sunset, but all the little moments around them that most people don’t even know have names. If you’ve ever wondered why the sky starts to brighten long before the sun actually peeks over the horizon — or why your streetlights turn off a little after sunrise — well, there’s a name (and science) for that.
Here’s a quick and dirty guide to those solar events — without the math(s) (I’ll also provide an example of the time for each, using Sydney as a basis on the longest day of 2025—Sunday, 21 December 2025):
🌌 Astronomical Dawn
This is the very first hint of light — when the sun is still 18° below the horizon. To the untrained eye, it’s still dark. But if you’re stargazing, this is when the deepest part of night ends.
Time on 21-Dec-2025: 05:12am
🌊 Nautical Dawn
Now the sun is 12° below the horizon. If you were at sea, you’d just begin to make out the horizon line. Still a ways to go before your morning jog, though.
Time on 21-Dec-2025: ~05:25am
🌅 Civil Dawn
Sun is 6° below the horizon. You can see well enough to walk around without a torch. This is when the streetlights typically turn off. Birds start up. It’s the beginning of “usable” daylight. This also coincides with when a VFR pilot is allowed to fly.
Time on 21-Dec-2025: ~05:41am
☀️ Sunrise
The upper edge of the sun pops over the horizon. Day officially begins. You’ve made it.
Time on 21-Dec-2025: 05:41am
🕛 Solar Noon
The moment the sun reaches its highest point in the sky. It’s when shadows are shortest and the sun is directly north (in the Southern Hemisphere). It’s often not exactly at 12:00 — thanks to time zones, daylight saving, and your exact position on Earth.
Time on 21-Dec-2025: 12:53pm
🌇 Sunset
Same deal in reverse. The sun dips below the horizon — but daylight doesn’t disappear instantly.
Time on 21-Dec-2025: 8:04am
🌃 Civil Dusk
This is the moment it gets just dark enough that you’d want lights on. Streetlights flick on. VFR pilots need to land before this time.
Time on 21-Dec-2025: ~8:33pm
🌊 Nautical Dusk
Horizon? Gone. Sky’s still deep blue, but we’re halfway to night.
Time on 21-Dec-2025: ~8:45pm
🌌 Astronomical Dusk
The sun is 18° below again. True darkness. Ideal for telescopes, deep thoughts, or collapsing into bed.
Time on 21-Dec-2025: ~9:05pm
I’m thinking of putting this sort of information — starting with iOS — that plays with this stuff in a fun, visual, and maybe even useful way. Whether it’s for sleep, photography, rituals, or just curiosity, I think there’s something oddly grounding about tracking light this precisely.
Another idea for the app is the length of the day. At the solstices, the sun seems to linger. It’s not just the longest or shortest day of the year — it’s also the point where daylight changes the slowest.
I’m playing with ways to show that in the app — maybe a kind of “light curve” or daily delta visual. Still mulling it over.
The idea came to me because I’d like to showcase an app idea built with vibe coding. I’ll likely be using Claude Code. There’s no roadmap. No deadlines. Just following the light.
Stay tuned. 🌞