Back in February 2013, the skies over Russia were lit by the fall and explosion of a large meteor. The scavenger hunt for meteorite pieces that followed turned up lots of conically-shaped chunks of rock, consistent with other meteors. Why do so many meteorites end up in this shape? There are a couple factors influencing it.
The first is that erosion during flight tends to shape initially spherical meteor chunks into broad cones. And that shape, it turns out, is remarkably stable in flight. By dropping cones of various geometries, researchers can test how stable they are in flight: do they change orientation, flutter back and forth, or drop straight down? Slender cones (below) tend to invert and tumble. Very broad cones flutter back and forth as they fall. But for an intermediate cone angle – similar to the one found in meteorites – the cones stay perfectly oriented, so once the rock erodes into that cone, it will keep that shape. (Image and video credit: K. Amin et al.)