NASA has launched its $ 1.5 billion spacecraft designed to "touch the Sun."
"Three, two, one and take off!" said a NASA commentator as the Parker Solar probe soared into the sky aboard a Delta IV-Heavy rocket from Cape Canaveral, Florida, at 3:31 a.m. (0731 GMT).
The planned takeoff yesterday was delayed when a red flag appeared during the final checks.
The unmanned spacecraft aims to get closer than any human-made object in history to the center of our solar system.
NASA says the historic mission will help protect the Earth by revealing the mysteries of dangerous solar storms.
The probe is designed to immerse itself in the Sun's atmosphere, known as the corona, during a seven-year mission.
It is protected by an ultra-powerful heat shield that can withstand unprecedented levels of heat and radiation 500 times greater than that experienced on Earth.
NASA has announced that the mission was the first spacecraft to "touch the Sun."
Actually, it should be 3.83 million miles (6.16 million kilometers) from the surface of the Sun, close enough to study the curious phenomenon of the solar wind and the Sun's atmosphere, known as the corona, which is 300 times hotter than its surface.
The car-sized probe is designed to help scientists better understand the solar wind and geomagnetic storms that risk causing chaos on Earth by knocking out the power grid.
These solar outbursts are little known, but they have the potential to eliminate the energy of millions of people.
A worst-case scenario could cost up to two trillion dollars in just the first year and take a decade to fully recover, experts warned.
"Parker Solar Probe will help us do a better job of predicting when a solar wind disturbance could impact the Earth," said Justin Kasper, project scientist and professor at the University of Michigan.
Knowing more about the solar wind and space storms will also help protect future explorers from deep space as they travel to the Moon or Mars.
The probe is protected by an ultra-powerful heat shield that is only 4.5 inches (11.43 centimeters) thick, allowing the spacecraft to survive its closest shave with the fiery star.
Even in a region where temperatures can reach more than one million degrees Fahrenheit, sunlight is expected to warm the shield to about 2,500 degrees Fahrenheit (1,371 degrees Celsius).
If everything works as planned, the interior of the spacecraft should remain at only 85 degrees Fahrenheit.
The goal of Parker Solar Probe is to make 24 passes through the crown during its seven-year mission.
"The sun is full of mysteries," said Nicky Fox, project scientist at the Applied Physics Laboratory at Johns Hopkins University.
"We're ready, we have the perfect payload, we know the questions we want to answer."
Namesake of 91 years of age
The spacecraft is the only NASA probe in history that bears the name of a living person; in this case, the 91-year-old solar physicist Eugene Parker, who first described the solar wind in 1958.
Parker said last week he was "impressed" by Parker Solar Probe, calling it "a very complex machine."
The director of the scientific mission of NASA, Thomas Zurbuchen, said on Saturday that Parker is an "incredible hero of our scientific community", and qualified the probe as one of the "strategically important" missions of NASA.
Scientists have wanted to build a spacecraft like this for more than 60 years, but only in recent years has thermal protection technology advanced enough to be able to protect sensitive instruments.
The tools on board will measure the high-energy particles associated with the eruptions and coronal mass ejections, as well as the changing magnetic field around the sun.
A white light camera will take pictures of the atmosphere right in front of the sun.
When it approaches the Sun, the probe will travel quickly enough to go from New York to Tokyo in one minute, some 430,000 miles per hour, which makes it the fastest man-made object.