Milky Way

A composition, not a map

The band was laid on the real galactic plane for a day: honest, and useless as a cover. Tonight the plane is a steep line down one side of the screen, next week it’s somewhere else, and a cover needs a shape you can set type against. So the band stays across the page, tilted a little, on a long slow swell, and borrows the real sky where the sky helps.

Where the stars are

The clouds aren’t invented. The catalogue’s stars within twelve degrees of the galactic plane are counted per six degrees of longitude, and the flow slows where the count is high, so a traffic jam of points gathers where the real star clouds are: toward Sagittarius, where the galaxy’s centre is, and Cygnus. The band spans a stretch of the plane centred on the part of it you’d be facing right now, so the clouds slide along the band as the sky turns through the night. The bars below are that count.

0° Sagittarius, the centre · 80° Cygnus · 180° the anticentre, toward Auriga · the orange bar is the part of the plane the screen faces now

Points as stars

A point is written into the sky texture as a star: a magnitude for its brightness and size, a seed for its twinkle, its offset inside the cell so it moves smoothly. The core sits in the steady window and holds; the edges sit near the limit and twinkle with the old swell. By seed, a few points are the larger squares.

The flow

Points drift along the band a few cells a second, each at its own pace, riding a spring toward the plane so the swell moves them without a jolt. Core points keep close to the plane; halo points swing wide, so the density falls off the way a galaxy’s does.

Gravity letting go

On the homepage the band is tied to the scroll. At the top it’s gathered: a tight core along the plane with its clouds. As you go down, gravity lets go: the core and the halo spread wider, the clouds thin away, and the halo rises a little faster than the core so the two planes slide past each other. By “Say hello.” the points are dispersed across the whole field. Nothing eases; the band is a function of where you are.

A pointer held still

Over the band the pointer is the orange point, and pressing clears a pocket like everywhere on the site. Hold it still instead, and once the ring has rested the nearby points drift in and gather a small cloud around it, which lets go when you move on.

Day, cloud, and one planet

By day the band is fainter, blending over the forty minutes either side of today’s sunrise and sunset; under cloud it dims by the cover. The one orange point is the brightest planet above the horizon right now, where it really is, as on the star map.

From the lab

The band started on the field lab as one of nine rest states for the cover, a wave across the middle of the screen with gravity and clumping sliders. It won over the stars for a day, lost to them, and came back as a switch in the footer. Its own page came with the real clouds.

Care you don’t see

With reduced motion on, the flow and the twinkle stop and the band stands still. If the graphics context is lost, the 2D mirror takes over. The field is decoration to assistive technology, and the page reads without it. The whole band costs well under a millisecond a frame.