Rendering "long exposure" star trails in the sky

Basically, I’m trying to reproduce a timelapse image of the stars rotating, like this image.

Right now, I have a separate “skybox camera” that sits inside a sphere mesh. The sphere faces inward to the skybox camera and has a starry texture applied. It can be rotated, thus giving the appearance of the stars rotating.

Now, I need to find a way to get those traced lines as the stars rotate. The effect can be cheesed/faked by setting the camera to “don’t clear”, but that would also mean that I would have to fix the player in place so they don’t mess up the rotation. It’s also potentially buggy.

The only other thing that would come to mind is duplicating the sphere mesh with the stars and offsetting the rotation multiple of each duplication, something like “onion skinning” the star-sphere. But that would quickly increase polycount, and may not be a perfect visual result.

Does anyone know an image effect or shader to get a ‘long exposure’ effect like this? Or a stable way to reproduce the trails left by a camera set to ‘don’t clear’?

Thank you!

  1. Use a line renderer as ozone said, or
  2. Use a trail renderer, or
  3. Use a particle system that produce none moving particles (use the same texture as your star, also make sure they die with the correct time, or you will have just circles in your sky)
  4. Use some magical method that I’m not aware of as of yet