PITTSBURGH—A meteor that caused an earthshaking boom over suburban Pittsburgh on New Year’s Day exploded in the atmosphere with an energy blast equivalent to an estimated 30 tons (27,216 kilograms) of TNT, officials said. NASA’s Meteor Watch social media site said late Sunday a “reasonable assumption” of the speed of the meteor at about 45,000 mph (72,420 kph) would allow a “ballpark” estimate of its size as about a yard in diameter with a mass close to half a ton (454 kilograms). If not for the cloudy weather, NASA said, it would have been easily visible in the daytime sky—maybe about 100 times the brightness of the full moon. A nearby infrasound station registered the blast wave from the meteor as it broke apart, enabling the estimates. National Weather Service meteorologist Shannon Hefferan told the Tribune-Review that satellite data recorded a flash over Washington County shortly before 11:30 a.m. Saturday …