  When a granular material is impacted by a sphere, its surface deforms like a
liquid yet it preserves a circular crater like a solid. Although the mechanism
of granular impact cratering by solid spheres is well explored, our knowledge
on granular impact cratering by liquid drops is still very limited. Here, by
combining high-speed photography with high-precision laser profilometry, we
investigate liquid-drop impact dynamics on granular surface and monitor the
morphology of resulting impact craters. Surprisingly, we find that, despite the
enormous energy and length difference, granular impact cratering by liquid
drops follows the same energy scaling and reproduces the same crater morphology
as that of asteroid impact craters. Inspired by this similarity, we integrate
the physical insight from planetary sciences, the liquid marble model from
fluid mechanics and the concept of jamming transition from granular physics
into a simple theoretical framework that quantitatively describes all the main
features of liquid-drop imprints in granular media. Our study sheds light on
the mechanisms governing raindrop impacts on granular surfaces and reveals a
remarkable analogy between familiar phenomena of raining and catastrophic
asteroid strikes.
