You can create star trails in Photoshop in three easy steps. It’s really quite easy!

Star trails are magical. They show the celestial movements of the stars over a long period of time. And they’re easy to create.

You’ve taken some photos of the night sky in succession, one right after another, using a tripod to keep everything steady. And now you want to use Photoshop to “stack” them to make them into larger star trails. Photoshop has some nice advantages for “stacking”, and I’ll point some of these out near the end.

1. Stack your photos

Load files into stack screenshot.
Load files into stack. We’re gonna create some star trails!

Simply go to “File”. Select “Scripts”. Then select “Load Files into Stack” as shown above. 

2. Select which files you want stacked

Dialogue box for stacking for star trails
The dialogue box for selecting the files you want to “stack” into star trails.

This too is straightforward. Hit the “Browse” button. Then simply navigate to where your files are and select them and hit “OK”. You don’t need to check any of the boxes below assuming that your camera and tripod did not move.

3. Let the stars shine through!

Photoshop will stack all of your photos. If you had printed all of your individual photos, it would be as if they were all stacked on top of each other in one neat pile. Photoshop is just doing this digitally. Lean back and relax. If you have lots of photos and a slow computer, go get a drink.

Photoshop Layers lighten. Star trails
Hey, alright! Photoshop has stacked your photos! But now we need to change the opacity of the Layers from “Normal” to “Lighten”.

Once Photoshop is done, you’ll think, “Okay….I see all the layers of photos on the bottom right side….but I don’t see any star trails!” And you wouldn’t see them if you had stacked all your printed photos one on top of the other either. 

But here in Photoshop, we can turn our stacked “digital papers” (our layers, in other words) into “magic paper”. Cool, huh? 

First, highlight all the layers except the very bottom layer. 

Then go to the Layers Tab just above where all your images are stacked; You’ll see a pulldown menu that says “Normal”. Change that to “Lighten”. Wow! Let the star trails shine through!

Photoshop Layers lighten for star trails
Instant star trails! I never get tired of seeing how it all comes together. Where the red arrow is pointing, you change that from “Normal” to “Lighten”, then lean back and smile. Yeah. You just created some star trails!

If you look at this photo above, you can see some airplane trails and some lights from me mistakenly shining the light into the camera while illuminating the giant dragon sculpture. Next, we will discuss how to get rid of that.

Bonus Tip: Getting rid of airplane trails or unwanted lights

Some people don’t want airplanes in their star trails. Or maybe you mistakenly shine a light in the camera and you don’t want that. This bonus section is for you. This is one of the nice aspects of using Photoshop.

A lot of people choose not to do this. That’s okay. It’s your photo. You’re in charge. You do what you want.

Photoshop masks for star trails
The red arrow is pointing to Layer Masks. Here, I’ve created a lot of Layer Masks, one for each Layer, mostly to get rid of lots of airplane trails. There were probably ten airplanes that flew through while I created this image because this location is directly in the flight path of San Diego. I also got rid of some inadvertent lights while light painting and my ghostly shadow image from standing in place a little too long.

But if you want to try this, you can rid yourself of them by creating Layer Masks. Those are those white rectangles to the right of the layers in our example below. 

Creating Layer Masks so we can mask out unwanted stuff

Select one layer that has the airplane trails or unwanted light that you don’t want. You’ll create a Layer Mask that will block this out. Go to the top menu. “Choose Layer” > “Layer Mask” > “Reveal All”. This should produce a white rectangle to the right of your selected layer.

Then select the Brush tool. This is located on the left side of the image. Choose the black color. Make sure that the white Layer Mask is selected instead of the actual layer itself. Then simply start painting away on the area that you want to be concealed. You should see the unwanted item begin to disappear. The black color stops that one part of the image from shining through! It’s like magic!

Rattledragon star trails photo
The enormous rattledragon sculpture in Borrego Springs, California. The sculpture was created by Ricardo Breceda. This image is 28 minutes total exposure. Each individual photo was a two-minute exposure at f/6.3 and ISO 200. The star trails are relatively straight because I am zooming in from farther away and we are not facing directly north or south, so they tend to be straighter and longer when they are farther from the North or South Celestial Poles.

It’s really that easy. If you don’t like it, hit “Undo” (or paint over what you did after selecting a white color). 

Additional tips

Layer Masks can be used to get rid of “hot spots” from your light painting as well. Or shadows. Really, anything that only exists on one layer, you can eliminate non-destructively. If you don’t like it later, go back and change it.