people reported there were sonic booms going on as well as it came through the atmosphere. >> how often does it happen? >> we go through it every year. they are rarely anything like that. most of the time we see small showers. this was an explosion. >> what's going on in iceland. there's a huge eruption. flights to europe are stopped. how long could it last? >> it could last a long time. this is a significant event for europe and plane travel. you cannot fly a jet plane through ash. i know it looks all compacted and you could fly around it. as it gets more diffuse, away from the volcano itself, there's ash in the sky and you can't see it. ash melts in the jet plane itself. it melts and becomes like lava glass. you don't want that in your jet plane because in the jet itself,