Weird blur when firing projectile 2D

I'm creating a small infinite sidescroller space game, and it's working quite well. The only thing is, that whenever the 2D projectile the spaceship fires is going faster than a certain speed. It creates a weird kind of blur, which is so bad that it looks like there are two projectiles, and sometimes even four. I can't really take a screenshot of it, because when the game is paused, it shows only one projectile.

I believe it is called ghosting, and I'm clueless on what to do about it.