From Twitter https://twitter.com/: Born #OTD 1934, astronomer Carl Sagan was one of the foremost science communicators of the 20th century http://physicstoday.scitation.org/action/cookieAbsent #histSTM https://twitter.com/PhysicsToday/status/928626991477215234/photo/1 https://chirp.cooleysekula.net/attachment/42498