Aurora

A frozen lake, a black spruce shore, and the northern lights going off overhead like nobody is watching. One sky, stretched across every monitor you own.

How it works

• The curtains are simulated, not looped. Each band is a thin sheet about a hundred kilometers up, so it folds, sags and leans the way the real thing does, with green at the hem and violet at the top.
• The ice is a mirror with opinions. Bare patches reflect the sky, dim and blurred. Snow drifts do not. The shoreline blocks its share of the reflection.
• The sky actually turns. Stars and the Milky Way rotate about the pole if you want them to. They twinkle more near the horizon, where there is more air in the way.
• Every so often a substorm rolls through, and it travels the length of the world, one monitor after another.

Things you can do

• Release a lantern: click the ice. It lifts off, glows, flickers in its own reflection, and drifts away on the wind.
• Wish on a meteor: click the sky to fire one. The bright ones leave a faint train that hangs around for a few seconds.
• Conjure a surge: click anywhere and a wave of brightness runs out both ways from that spot.
• Light a fire or lamp: click the shore for a campfire, or click a cabin to switch its lamp. Click a fire again to put it out.
• Customize: aurora color (classic green, violet storm, rare crimson, teal), activity, star density, moon phase with moonlight on the snow, time-lapse speed, snowfall, and lanterns that release themselves.

Every monitor

• In Chrome or Edge, open Customize and click Every monitor. The browser asks to manage windows on your displays; say yes, then click once per extra screen and once inside each new window. Meteors, satellites, lanterns and substorms all cross from one screen to the next.
• A portrait monitor just sees more of the lake: a cabin, some tracks, and someone out there with a tripod who has clearly been standing in the cold for a while.
• Add #embed to the address for just the sky with no controls, handy for kiosk and web-screensaver setups.