NASA project manager Andy Driesman said: "We will fly by Venus seven times throughout the mission".
Nicky Fox, project scientist at the Johns Hopkins University Applied Physics Lab, said: 'The sun is full of mysteries.
It is the first space craft to be named after a living person - astrophysicist Eugene Parker, 91, who first described solar wind in 1958. Saturday morning's launch attempt was foiled by last-minute technical trouble.
"The Parker Solar Probe will help us do a much better job of predicting when a disturbance in the solar wind could hit Earth", said Justin Kasper, a project scientist and professor at the University of MI. Liftoff took place from Space Launch Complex 37 at Cape Canaveral Air Force Station in the USA early today.
The corona holds the answers to many of scientists' outstanding questions about the Sun's activity and processes.
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. Parker watched the launch at Cape Canaveral and said it was his first time seeing a rocket blast off in person.
"I really have to turn from biting my nails in getting it launched, to thinking about all the interesting things which I don't know yet and which will be made clear, I assume, over the next five or six or seven years", Parker said on NASA TV.
"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.
The car-sized spacecraft will speed through space at 430,000mph - coming within four million miles of the Earth's nearest star by 2024.
At those speeds, the spacecraft will reach the sun by November, and scientists hope to have early data back from the probe by the end of the year.
To reach its target, the Delta 4 Heavy and a solid-propellant upper stage had to supply enough energy to counteract Earth's 18-mile-per-second orbital velocity around the sun, allowing the spacecraft to fall into the inner solar system.
Zurbuchen considers the sun the most important star in our universe - it's ours, after all - and so this is one of NASA's big-time strategic missions. "Why is the corona hotter than the surface of the sun?"
The probe is guarded by an ultra-powerful heat shield that can endure unprecedented levels of heat, and radiation 500 times that experienced on Earth. With a communication lag time of 16 minutes, the spacecraft must fend for itself at the sun.