Night Curtains: Aurora Borealis Simulator & Northern Lights Screensaver
Night Curtains is a free aurora borealis simulator and northern lights screensaver that renders procedural auroral curtains live in your browser. Set the KP storm level from a quiet arc to a full substorm, choose the landscape and palette, export any moment as a 4K wallpaper, or record an MP4 or animated GIF clip. The sky is generated in real time on your GPU, so it never loops and never repeats.
Built by: Chris Pirillo
Cost: free, no account required
Privacy: 100% client-side, nothing uploaded
Rendering: real-time procedural WebGL, never loops
Export: 4K PNG wallpaper, MP4 or animated GIF clips
NIGHT CURTAINS
The aurora needs WebGL to paint the sky, and this browser is not providing it. Try a current version of Chrome, Edge, Safari, or Firefox, and make sure hardware acceleration is turned on in your browser settings.
RECkeep this tab in front
RECORD CLIP
Format
Orientation
Resolution
Frame rate
Quality
Size
Frame rate
GIF is a 256-color format, so the aurora's smooth gradients will show some banding. For the cleanest clip, choose MP4.
Length6s
NIGHT CURTAINS
A live aurora borealis simulator and northern lights screensaver. The sky is generated on your GPU in real time, so it never loops. Tap the sky for a new scene, open the Field Station panel to dial the storm from KP 1 to KP 9, and export any moment as a 4K wallpaper. Built for anyone who wants the northern lights on a screen without flying to the Arctic.
Night Curtains is a free browser-based aurora borealis simulator and northern lights screensaver. It renders the aurora procedurally in real time on your GPU, so the sky never loops and no two minutes are ever the same. No signup, no install, no download.
Is Night Curtains free?
Yes. Completely free with no hidden limits, no account required, no watermarks, and no feature gates. The 4K wallpaper export is free too.
How do I use it?
Open the page and the aurora starts on its own. Click or double-tap the sky for a new random scene. Open the panel to tune the storm level, colors, landscape, and stars. From the panel you can save the current sky as a 4K wallpaper or record a short MP4 or GIF clip. Everything runs in your browser and nothing is uploaded.
Does it collect my data?
No. Everything runs locally in your browser using JavaScript and WebGL. Nothing you do here leaves your device. There are no servers, no uploads, and no tracking beyond basic anonymous page analytics.
What is the KP index?
The KP index is the real 0 to 9 scale scientists use to measure geomagnetic storm activity, and it is how aurora chasers decide whether tonight is worth staying up for. KP 1 to 3 is a faint arc near the horizon, KP 5 and up is a geomagnetic storm, and KP 7 to 9 can push the aurora overhead and far south of the Arctic. The storm slider here uses the same scale, from a quiet glow to a full KP 9 superstorm.
Why is the aurora green?
The classic auroral green comes from oxygen atoms about 100 to 300 km up, glowing when they are hit by charged particles from the sun. Higher-altitude oxygen glows red, which is why strong displays show red fringes above the green, and nitrogen near the lower edge can add a pink or purple border during intense storms. Night Curtains follows that same altitude-based color physics. For more procedural sky, try Cloudy Day or Cosmic Forge.
Can I put this on my TV?
Yes, that is one of the best ways to use it. Open the page in your smart TV's browser, or cast or AirPlay a browser tab from your laptop or phone, then tap the fullscreen button. Because the aurora is generated live, there is no loop point to spot. Fall Leaves works great on a TV too.
How is this different from aurora videos on YouTube?
Aurora videos on YouTube and Fire TV screensaver apps are pre-rendered loops. They repeat, they stream constantly, and you cannot change anything. Night Curtains generates the aurora on your own GPU, so it never repeats, works offline once loaded, and lets you control the storm intensity, colors, landscape, and stars. It is also an alternative to installed live-wallpaper software like Wallpaper Engine, with nothing to download.
Can I record a video of the aurora?
Yes. Open the panel and choose Record Clip to capture the live sky as an MP4 video (Firefox saves WebM instead) or an animated GIF, in landscape, portrait, or square, up to 15 seconds. Keep the tab in front while it records. GIF is a 256-color format best for short clips, so MP4 gives the smoothest gradients. For compressing or converting clips afterward, try Video Shrinker.
Does it show the southern lights too?
Yes, in the sense that the aurora australis, the southern lights, is the same phenomenon as the aurora borealis and looks identical. Whatever sky you build here is just as true to Tasmania or Antarctica as it is to Alaska or Norway.