for a "naturally occurring" process to create something we could suspect as a lightsail, I wonder about something, perhaps a comet, blowing a bubble. That is

for a "naturally occurring" process to create something we could suspect as a lightsail, I wonder about something, perhaps a comet, blowing a bubble. That is a layer of something what could form a membrane over something that could off gas. Both triggered by heat. Bubble is created and pops or deflates and the skin blows around for ever.