Guys, How to make a Crack on a Planet?

The are many ways to make cracks, but if you are referring to like zig-zag and sharp cracks refer to @Zenithspeed ‘s comment. But if you want canyons, you need a noise mask, a remap curve, and the noise. I know how to make rivers, and you make them similar to canyons, but they are more complicated to make, because their noises are different and they don’t need a mask.

to make cracks, use noise type Cellular, there will be two settings next to it
the first one can be "Euclidean", "Manhattan", "Natural", and "Euclidean No Overlap" — out of those, the first three are all suitable, but Natural is probably going to be the best
for the second option, use "Distance 2 Sub", the rest work differently, though some may give similar results
for the noise itself, a frequency of 5 to 100 (or even beyond) usually work best, and adjust strength as needed
you may also need domain warps or a remap curve to make them look better, but those are more advanced things and for basic cracks they aren't really needed

currently it's only possible on earth. Though theoretically, you can make crack on other planet with sufficient materials.