Future Space
Before talking about the invisible wall ( the Oort cloud) , let’s talk about what comets are. Comets are cosmic snowballs of frozen gases, rocks and dust, orbiting the sun. They are typically the size of a town.These comets while orbiting the sun, get close to it and in the process are heated. Upon heating, they emit dust and gases into a giant glowing head. The dust and gases form a tail that stretches away from these for millions of miles.
Credit Insane Curiosity