From Earth, it is 93 million miles to the sun (150 million kilometres), and the Parker probe will be within four percent of that distance. "Each time we fly by, we get closer and closer to the Sun".
The car-sized probe is created to give scientists a better understanding of solar wind and geomagnetic storms that risk wreaking chaos on Earth by knocking out the power grid.
It is the first time NASA has named a spacecraft after someone still alive.
The mission had been expected to launch on Saturday, but was delayed at the last minute due to a technical problem.
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The car-sized satellite was blasted into space from the Florida base at 3.31am eastern time (8.31am BST) on Sunday morning.
The Delta IV Heavy rocket thundered into the pre-dawn darkness, thrilling onlookers for miles around as it climbed through a clear, star-studded sky.
"The spacecraft must operate in the sun's corona, where temperatures can reach millions of degrees", Brown told ABC News via email. Seven Venus flybys are planned over the seven-year mission to fine-tune the trajectory, setting up the close-in aim points.
"Fly baby girl, fly!" project scientist Nicola Fox of Johns Hopkins University tweeted just before lift-off, urging it to "go touch the sun!" Parker was even there to see the launch - his first one ever. "What a milestone. Also what's so cool is hanging out with Parker during all this and seeing his emotion, too".
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.
"Wow, here we go!"
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It took one of the most powerful rockets in the world to get the mission moving - not because the probe is large or heavy, but because of the speed required to cruise through the solar system.
Scientists have been debating these questions for decades but NASA said technology has only come far enough in the past few decades to make the solar mission a reality. Among the puzzlers: Why is the corona hundreds of times hotter than the surface of the sun and why is the sun's atmosphere continually expanding and accelerating, as Parker accurately predicted in 1958? She urged it to "go touch the sun!" "We've looked at it".
Scientists have devised ways to ensure the automated and unmanned probe does not melt in the extreme heat and radiation. If there's any tilting, the spacecraft will correct itself so nothing gets fried. That's nearly 10 times closer than Mercury gets, and seven times closer than any previous probe.
"So we're already in a region of very, very interesting coronal area", Fox said. "It's incredible to be standing here today".
"We are going to be in an area that is so exciting, where solar wind - we believe - will be accelerating", said NASA planetary science division director Jim Green.
Bairstow & Woakes put England in strong position at Lord’s
Hosts England lost Keaton Jennings for 11 runs after a quick start, as Mohammed Shami provided the breakthrough for India . Chris Woakes hit his maiden Test century as England hammered home their advantage over India in the second Test at Lord's.