NASA has launched a spacecraft to the sun that will fly closer to our star than anything ever sent before.
The probe won't actually land on the sun, but it will make history - getting closer than any other man-made object.
The spacecraft has been named after 91-year-old astrophysicist Eugene Parker, who was one of the many spectators who arrived at the launch site to watch the historic moment.
Nasa has launched a satellite that will fly closer to the sun than any of its predecessors.
At a press conference last week, Parker said of his namesake mission: "I expect to find some surprises".
It eventually will get within 3.8 million of the sun's surface, staying comfortably cool despite the extreme heat and radiation, and allowing scientists to vicariously explore the sun in a way never before possible.
"The sun is full of mysteries", said Nicky Fox, project scientist at the Johns Hopkins University Applied Physics Lab.
A revolutionary carbon heat shield will protect it, while the tried-but-true practice of using water inside the craft to cool it down is also being utilised. But the probe's heat shield will still get hotter than lava while its instruments study the hellish environment in unprecedented detail.
The car-sized probe will give scientists a better understanding of solar wind and geomagnetic storms that risk wreaking chaos on Earth by knocking out the power grid.
If all goes well, the Parker Solar Probe will swing by Venus in about six weeks for a gravitational encounter that will help the spacecraft slow down still more.
It was the first rocket launch ever witnessed by Parker, professor emeritus at the University of Chicago. All I can say is: "'Wow, here we go.' We're in for some learning over the next seven years".
Finally, after two firings of the second-stage engine, the Parker Solar Probe and its Northrup Grumman solid-fuel upper stage were released from the Delta 4. On its very first brush with the sun, it will come within 15.5 million miles, easily beating the current record set by NASA's Helios 2 spacecraft in 1976.
"Until you actually go there and touch the sun, you really can't answer these questions", said Project Scientist Nicola Fox.
NASA hope the breakthrough journey will reveal why the sun's outer layer - the corona - is hotter than the surface.
"To me, it's still mind-blowing, " she said.
The spacecraft's heat shield will serve as an umbrella, shading the science instruments during the close, critical solar junctures.
Sensors will make certain the heat shield faces the sun at the right times and it will correct itself if it ends up at the wrong angle. "It's incredible to be standing here today".