Before JavaScript ate the browser, one good way to make a website interactive was to submit a form and let the server do the math.
John Walker’s Your Sky calls itself the interactive planetarium of the Web. It can generate a sky map for a chosen date, time and observing location, produce horizon views, or aim a virtual telescope at coordinates and catalog objects.
The page can also accept orbital elements for an asteroid or comet and plot the object’s position alongside an ephemeris for the Sun, Moon and planets.
That is a lot of astronomy packed into ordinary forms and server-generated images.
A web application before everything was called an app
Your Sky is useful partly because the interface exposes the astronomy instead of hiding it.
Latitude and longitude matter. Right ascension and declination matter. Magnitude limits, projection choices and observing direction are visible controls. The user is not merely shown “the sky tonight.” They are given the knobs that define the calculation.
The site offers three main views: a whole-sky stereographic map, a horizon view pointed in a chosen azimuth, and a virtual telescope that can be aimed at coordinates or catalogued objects.
The virtual telescope can even be bookmarked with custom settings encoded in the request, a very old-web solution to saving application state.
Your Sky is dated April 2003 and lists an update in February 2019, but the underlying style is older than the modern single-page application. The server does useful work. The URL and form parameters carry meaning. The result can be saved, linked and revisited.
For astronomy students, it remains a practical visualization tool. For web developers, it is a reminder that interactivity existed long before enormous front-end bundles became mandatory.
This site was found in CacheRat’s broader Ancient Web research corpus.
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Your Sky still does the job with forms, coordinates and a server that knows where the stars are.