Some of the universe's most extreme explosions leave behind almost no trace. The original explosion is unseen, but our observations can capture the long-lived echo it leaves behind as the shock front ...

United Launch Alliance was hoping to ramp up its new Vulcan rocket launches this year, but won't be launching any national security missions until it solves a recurring issue of booster nozzles ...

Several leaders voiced support for the operation — but most, including those who stopped short of condemning it, called for restraint moving forward.