U.S. lawmakers have increasingly used the debt ceiling to re-litigate congressional spending, risking default and sparking debate over whether to abolish the ceiling.

U.S. space exploration inspired a generation of students and innovators, but NASA’s role has diminished, and the number of global space competitors is growing.

As Europe has weathered a succession of economic crises, the European Central Bank has responded with an aggressive set of monetary policies that have redefined the bank’s original mandate.