What causes Asteroids to break free and attack planets?

Where do Asteroids come from? Could an Asteroid hit Earth without warning? How many Asteroids are there in our Solar System? And for today's awesome 5 Minute SMARTYQUIZ - check out the SMARTYQUIZ email. If you're not getting our free SMARTYQUIZ email, you are really missing out on making fun memories & locking in the learning with our research-backed gamification - it's our gift to you 3 times a week! Sign up here. For free home activities sign-up at www.WhoSmarted.com See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.