Making Comet Star Trails in After Effects

After watching a lot of how to videos on youtube, I though I would try to give back a little and share something I was playing with - and hadn't seen other people do.
I used Adobe After effects to combine a jpg sequence of star trails and using expressions was able to make comets using a custom slider.
Concept is to control the opacity of each layer in the comp as a function of its inPoint
Variables:
thisComp.frameDuration -- time duration for each frame
inPoint - time (on the comp timeline) when this layer becomes visible
outPoint - time (on the comp timeline) when this layer has ended
time - for the comp timeline
tframes = thisComp.layer("Variables").effect("DelayTime (frames)")("Slider")
tSecs = tframes / (1/thisComp.frameDuration)
linear(time,inPoint, inPoint + tSecs, 100, 0)

[@redswan6765]

love the tutorial, thankyou!

[@paulohstorch]

you saved my life, thank you!

[@BrentMantooth]

Post your results, love to see what you did!

[@luanmarques777]

How do I do to colorize the star trails?

[@BrentMantooth]

First don't over expose, then it is just saturation or vibrance

[@catydid2102]

Does this still work in AE ver 24.0.3? I can't seem to do the comet layer.