Why does the asteroid Dimorphos leave a trail after impact?

[tech99]

TL;DR

Dimorphos seems to be leaving a trail of debris after the spacecraft impact. But why should the debris be left behind?

Pictures have appeared showing the asteroid Dimorphos following its impact with a spacecraft and showing a trail being left behind. On further consideration, this is taking place in a vacuum, so there is no air resistance. Why is the debris forming a trail behind the asteroid?

 

[anorlunda]

Why is the debris forming a trail behind the asteroid?

Just a guess, solar wind and light pressure makes tails, just like the tails of a comet.