How Afterglow's live screensavers actually work
Every 'live' screensaver on this site is either computed on your device from real orbital mechanics, or fetched by a small server-side pipeline from a genuine public API. No source is faked — here's how each approach works.
A lot of screensavers here claim to show real data — an actual planet position, an actual SEC filing, an actual earthquake. That's an easy claim to make and a very easy one to fake. So it's worth explaining exactly how it's done, because the two techniques behind it are genuinely different.
Technique one: computed on your device
Some of the most detailed savers — Orrery, Planetarium, Moon Phase — never make a network request at all. They compute real planetary and lunar positions locally, in your browser, from published orbital elements (the same low-precision formulas astronomers use for quick ephemeris work). Give the code a date and it hands back a real heliocentric position, accurate to a fraction of a degree, for any day in the past or future.
The Astrology category leans on the same math. Sky Chart Wheel plots every planet's real geocentric ecliptic longitude around the zodiac. Planetary Retrograde Tracker checks whether that longitude is moving backward day over day — real apparent retrograde motion, not folklore. Moon Sign Tracker and Planetary Hours Clock work the same way, the second one deriving its 'hours' from your city's actual computed sunrise and sunset.
Technique two: fetched by a small server pipeline
Everything else — SEC Filings Feed, GBIF Species Occurrence Feed, World Bank Indicator Explorer, El Niño / La Niña Index Tracker — is fetched by a small Python job that polls each source's own public API on a schedule, normalizes the response into a plain JSON file, and republishes it as static content. Your browser just reads that file; the fetching happens ahead of time, off to the side.
The rule for that pipeline has stayed the same across every batch of savers added to this site: real, key-less or free-key public APIs only. If a source turns out to be dead, rate-limited beyond use, or requires paperwork we can't get through, the idea gets dropped rather than faked. A few ideas from recent batches — a World Bank tourism indicator that hung on the server side, a defunct data.gov endpoint — were cut for exactly that reason instead of shipping with placeholder numbers.
Why it matters
It would be much easier to fake all of this with Math.random() — nobody would know the difference at a glance. But the point of a data screensaver is that it's actually looking at the world. A feed that's wrong is worse than a feed that admits it's unavailable, which is why every one of these savers shows a plain 'feed unavailable' message instead of quietly falling back to fiction. Browse the full catalog to see the rest.