Handling collision between the same objects

I have a space game where asteroids crash into each other. I want to place a particle effect between the two asteroid 1 and 2, but I don't see anyway to get the other asteroid's information. Is there a way to do this, or do the objects have to be different types?

Ok, I found a way to do it. I added two variables and a sub event.

sub event does For Each Asteroid: add x and y to variables.

then there is another sub event with no condition that creates the particle at X/2 Y/2.

Is that the best way to do it, or is there a more compact way?

<img src="http://i.imgur.com/iQl8S6k.png" border="0" />