Starfield Screensaver

What it does

Stars appear far off in the middle of the screen and stream outward as they come closer, growing and brightening until they slide past the edges. Press Start, or Go Fullscreen to fill the screen; until you do, it is a still picture of the same field.

Speed and Density each have three steps, and both can be changed while it runs. Slow and Calm make a quiet backdrop; Fast and Busy make the old "flying through space" screensaver.

Why the stars do not twinkle

Real stars twinkle because their light passes through moving air on the way to your eye. On a screen, a twinkle is simply a small flicker, repeated across hundreds of points — and flicker is something this site does not show. So each star holds a steady brightness. It starts far away, tiny and dim, brightens gradually as it approaches, and fades out if it passes close by, so nothing flashes into view or blinks out.

It is not a map of the sky

The stars are placed at random. They are not real stars, the view is not pointed anywhere, and the speed has nothing to do with light-years; it is a pattern for a screen, nothing more.

Using it

• On a spare monitor, full screen with Slow and Calm reads as a dark backdrop with a little movement in it.
• In a dark room, the black field keeps the light low. For no light at all, the Black Screen is simpler; for the time instead, the Fullscreen Clock.
• To leave it running, switch on Keep screen awake. It is off by default, held only while the stars move, and the status line says whether your browser agreed.