We are looking from our point of view to the asteroids who can destroy life on a big part on the crust of the earth. But what if too many big asteroids hit the sun and thereby making the sun to burp the stuff out that it does not really need. I am thinking at dust that was gathered in or out our solar-system. 

There are theories that propose solar-bursts in big time-frames that could do minimum as much damage to earth as big asteroids. Like i could understand it, we could be not far away from such possible event due to big asteroids passing by or impacting on the sun or just an event that returns every same amount of time which could create as an after-event a solar-dust-shell-burst also known as micro-nova's.

This would be heat, matter and radiation coming at great speed towards us with possible side-effects like crust-movements with additional ocean-water displacement around the whole earth. And as reaction to the heat and energy income we would have a very big ice-time. This would be in conjunction with the dieing of many life-forms and altering the dna/rna structures from life that survived the event due to deep radiation.

Grtz, Dirk.