NOTE My question is different from this previous one. What could be the physics behind witches flying on broomsticks?
- It is different because the phenomena in my question are not actually witches - they only have that appearance when seen in silhouette. They are not human or magical at all.
On arriving at a far-off planet, space explorers see what appear to be witches flying around on brooms. These seem to be of the traditional type as shown in the picture. However they are not human, but some kind of local phenomenon. The silhouette looks like a witch by pure coincidence.
Without using magic and on a roughly Earth-like planet, that has never seen humans before, what could these things be and how can they fly? I'm assuming that what look like arms, legs and hat are not actually that but some other types of appendage. For some reason they only fly at night.
Any scientific explanation is acceptable. No magic is allowed. A rough sketch of the actual anatomy or mechanism of these things would be greatly appreciated.