recently on c-span's q&a, nancy cabot -- chabot from johns hopkins discussed this recent mission. >> i heard there is a comment you do not like the look of. tell me about it. you have 20 minutes. >> is five to 10 km across. >> that is a clip from don't look up. it is a disaster movie senator and meteors striking earth but now science is catching up with art and you are involved in a project called dart revolving around this. tell me about it. susan: we have seen news reports of the past about meteors striking. what is the difference between an asteroid and meteor? >> when they get bright in the atmosphere, you can look up and see meteors come in. some make meteorites, which are the rocks that survive here on the planet. it really depends on the size when talking about objects. a meteor hits the earth once every year, roughly. i got my phd studying meteors. i love them. they are like free samples from space. it's not all bad. there is quite a lot of good about it. it's just when it gets bigger that you can have devastation. so it is important to distinguish between the size and object

recently on c-span's q&a, nancy cabot -- chabot from johns hopkins discussed this recent mission. >>s a comment you do not like the look of. tell me about it. you have 20 minutes. >> is five to 10 km across.