NASA says a fireball as heavy as an elephant caused the double boom that rang out over New England. The agency said Monday, the meteor was about 5 feet wide and travelling at an estimated 42,000 mph when it entered Earth’s atmosphere. NASA says when it broke up miles above New England on Saturday, the energy released was equivalent to about 230 tons of TNT, accounting for the booms. Initially, the event prompted widespread speculation. Some people in Massachusetts and Rhode Island posted that they thought there had been an earthquake or a tree had fallen on their home.