You can imagine meteors as lightning in the sky leading to lumpy-looking meteorites on the ground. But not all meteorites are lumps. A considerable population, like the remains of the Chelyabinsk puff of 2013, is particularly conical. A team of scientists believes to know why.
A group of New York University researchers are studying how things on Earth are shaped by forces such as erosion and eruption. They noted in their past experiments that a solid clay block formed into a cone shape as water flowed past it. You could apply this story to meteorites.
"We now have a self-contained story behind these conical meteorites," said study author Leif Ristroph to Gizmodo. "Erosion forms a cone and by lucky coincidence the cone, which it likes to carve, is also stable in flight." The team looked at the water flowing past the clay, which eroded the clay into cones. Meteorites moving through the air are more like this arrangement than you might think, as both objects are provided with a liquid-like force that passes them. But in one important respect they are different: the clay in their first experiment was in a fixed position as the water passed, but meteors fly through the air. Therefore, the researchers developed an experiment to study the formation of these conical meteorites.
In the latest phase of the experiment, researchers threw many small cones at different angles into a 2 foot tall water tank. Too thin spindles turned or fell over, and too-wide spikes fluttered and swayed like a falling leaf. But cones of just the right angle between 30 and 50 degrees maintained their landing direction, as shown by the paper published in the Proceedings of the National Academy of Sciences. These are cones that resemble the conical specimens found by meteorite hunters.
The experiment does not answer all the questions. For example, does the air erode the hot space rock into a stabilized conical shape that falls on the ground, or do these objects already reach the atmosphere as right-hand cones? These are questions the researchers want to answer next, the study's first author, Khunsa Amin, told Gizmodo.
Still, it's something that you appreciate about nature – somehow there are meteors that maintain the same orientation as they plunge to Earth, and we can thank Physics for that.