Delta 4 launch seen from press viewing site (members only)

The first months of observations of the solar system’s biggest planet from NASA’s Juno spacecraft have revealed huge swirling polar cyclones, previously-undetected structures and motions beneath Jupiter’s distinctive clouds, and the first evidence for what lies at the core of the gas giant, scientists said Thursday.

Successfully put through its countdown paces in a critical pre-flight test Thursday, America’s largest rocket currently in service moved closer to a June launch for the U.S. intelligence community.

Ground controllers pressurized the Juno spacecraft’s propulsion system Tuesday to prep for a July 4 rocket firing by the probe’s UK-made rocket engine that will steer the spinning, solar-powered robot into orbit around Jupiter.