Conchita said in August of 1980 that an event that will start the Warning would be an event in the sky that:

To me, it's like two stars... that crash and make a lot of noise and a lot of light but they don't fall".

In my opinion, it does not have to physically be 2 actual stars, but it only “looked like” that to her. ( best way to describe it ) Notice if 2 stars actually collided, there would be the debris falling to earth, but she mentions specifically" they don't fall ".

It might be possible that a nuclear missile could be intercepted in space by a anti-ballistic missile, causing the huge explosion, and that would also explain why there is no debris, as there would be if two real stars collided. Remember that the Warning comes “when things are at their worst”. (This could refer to God preventing a World War 3).

If it were Asteroids colliding there would be A LOT of debris ! It’s possible that God just makes a brilliant burst of light. (This way there is no harm from anything falling to earth). I guess we wait and see.