The sky above you

A construction-site page needs a picture. You take a gradient, scatter a few dots on it, call it a starfield, and you are done in an hour. We built a planetarium instead.

It does not show a starfield, it shows yours: 54 constellations, the band of the Milky Way, named bright stars and clickable galaxies, clusters and nebulae — computed for your place and your clock. If Orion stands over your city right now, Orion stands here. If he does not, the sky is empty where he would be.

The place comes from your timezone, not from a location prompt: no dialog, no permission. 77 cities are selectable, and a date and time control scrubs the sky forward and back. By day the same mechanics compute the sun's position and colour the twilight; the stars do not disappear, they are simply outshone.

It is operated like an instrument rather than a page: the mouse pans and tilts gently, the compass strip at the top spins the sky, scrolling zooms. Hold still and it gives you a tour — the view glides to the nearest constellation, fades in its name, and moves on. One click holds it, a second lets it go.

None of this sells an app. It shows how the work is done here: nobody writes celestial mechanics for a placeholder.