The famed astrophysicist was criticized Sunday for a tweet that downplayed the significance of the Dayton and El Paso mass shootings. On his Facebook page this morning, Tyson apologized. "My intent was to offer objectively true information that might help shape conversations and reactions to preventable ways we die," he wrote. "Where I miscalculated was that I genuinely believed the Tweet would be helpful to anyone trying to save lives in America. What I learned from the range of reactions is that for many people, some information –-my Tweet in particular -- can be true but unhelpful, especially at a time when many people are either still in shock, or trying to heal – or both. So if you are one of those people, I apologize for not knowing in advance what effect my Tweet could have on you."