US space agency Nasa has launched its mission to send a satellite closer to the Sun than any before.
The Parker Solar Probe rocket lifted off from Cape Canaveral, Florida.
The probe is set to become the fastest-moving manmade object in history. Its data promises to crack longstanding mysteries about the Sun's behaviour.
It is the first space craft to be named after a living person - astrophysicist Eugene Parker, 91, who first described solar wind in 1958.
"Wow, here we go! We're in for some learning over the next several years," he said after watching the lift-off from the scene. The University of Chicago professor said he had been biting his nails in anticipation.
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Image caption Astrophysicist Dr Eugene Parker with a model of the Parker Solar Probe that he inspired
The Delta-IV Heavy rocket - which was carrying the probe - launched at 03:31 local time (07:31 GMT).
It came after a failed attempt the previous day, when a last-minute alarm caused the agency to miss its 65-minute weather window.
Just under an hour after the launch, Nasa confirmed that the spacecraft had successfully separated and the probe had been released into space.
