My wife and i were driving north on highway 54. approximately 10 miles s. of jefferson city. she brought to my attention this black ring in the sky in front of us. i was driving so she grabbed her phone to take a photo. after the snapshot, she took it upon herself to start recording video. good move. after discussing it and trying to understand what we just saw, i wish we would've stopped to study it closer. we did check the review mirrors as we drove out of sight. the object was still there as we drove away. at first we thought it was a smoke ring. but as we approached it, the black ring looked dense. it definitely was not smoke. if i had to guess it was approximately 500 feet high. and 30 to 50 feet in diameter. the object was stationary as we passed by.