Katie Colaneri reports Chevron Appalachia will be fined nearly a million dollars for a gas well explosion last year that killed one contractor. Elana Gordon explains contingencies in place in Pennsylvania and Delaware if the Supreme Court strikes down subsidies for insurance under the Affordable Care Act. Peter Crimmins files his first report from Europe, where he’s touring with the Philadelphia Orchestra. Franklin Institute Chief Astronomer Derrick Pitts joins us for a weekly look at the skies. And Chris Satullo considers the future of TV political advertising.