In the Battlestar Galactica episode "Downloaded", there's a scene where Helo and Chief Tyrol are casting Hera's ashes into space. The ashes seem to float away to the rear as if carried by some gentle breeze.
Given that this is space, shouldn't the ashes keep pace with the Raptor since they'll be at the same speed on release?
There seem to be two (possibly three) factors that are causing the apparent motion of the ashes;
As you can see from the screengrab, the raptor is firing its engines to maintain position within the fleet. Any particles released from inside would therefore travel backwards, relative to the ship.
The fleet appears to be under power (we see several of the ships firing their engines) which would explain why the Raptor is needing to accelerate to maintain their own position. Since BSG vessels use reaction-based sublight engines and since the raptor is positioned dead-centre in the middle of the fleet, we can imagine that the exhaust gases and backwash from the fleet vessels nearby would create a wind-effect on any small particles.
To the left of the image, you can see that the fleet is passing some kind of gaseous nebula. Their position outside the cloud may not be enough to create a visible disturbance but the gases could easily have an effect on small particles. There may also be some gravitational effects if the nebula is large enough.
