NASA is set to launch a spacecraft designed to give its scientists their closest-ever view of the star and the mysteries of its corona.
The probe was scheduled to launch at 8.53am UK time on the back of a United Launch Alliance Delta IV Heavy rocket, the second most powerful rocket in operation globally.
Just minutes beforehand, however, NASA announced the launch had been delayed, saying the probe was "in a no-go status as we await further details".
"Teams are investigating a condition," they added on Twitter.
As the Parker Solar Probe probe orbits the sun, it will experience extreme radiation and temperatures as high as 1,377C (2,510F) – close to the melting point of steel.
To handle the heat it has been covered with a special 4.5 inch (11.3 cm) thick carbon-composite shield capable of withstanding temperatures up to 1,650C (3,002F).
It will get more than seven times closer than the current record holder for a close solar pass, a record set by the Helios 2 spacecraft in 1976.
"The primary science goals for the mission are to trace how energy and heat move through the solar corona and to explore what accelerates the solar wind as well as solar energetic particles," explained NASA.
"Scientists have sought these answers for more than 60 years, but the investigation requires sending a probe right through the 2,500 degrees Fahrenheit heat of the corona.
"Today, this is finally possible with cutting-edge thermal engineering advances that can protect the mission on its dangerous journey.
"Parker Solar Probe will carry four instrument suites designed to study magnetic fields, plasma and energetic particles, and image the solar wind."
After it launches, the probe will travel at 430,000mph, the fastest speed ever achieved by a spacecraft.
NASA stated: "Parker Solar Probe will provide unprecedented information about our sun, where changing conditions can spread out into the solar system to affect Earth and other worlds."
The probe is going to fly directly into the sun's atmosphere and trace the movement of energy and heat with the particles that form solar winds.
It will take six years for the probe to reach its closest point to the sun, in 2024, by using Venus' gravity to bring itself nearer and nearer to the star.
The probe will help scientists understand more about the nature of the sun by taking measurements of solar winds, a flow of ionised gases.
If scientists understand more about solar activity, they could use it to predict large solar eruptions that pose a threat to satellites orbiting the Earth.
Scientists also hope the probe can help them to answer why the corona, the outermost layer of the sun's atmosphere, is 300 times hotter than its surface.
This is a phenomenon that has baffled NASA scientists because the sun's atmosphere "gets much, much hotter the farther it stretches from the sun's blazing surface".
The probe, which will launch from Kennedy Space Centre in Cape Canaveral in Florida, is named after the American astrophysicist Eugene Parker.
It is the first time that NASA has ever named a spacecraft after a living researcher, and NASA said it was making history by honouring Dr Parker, the American astrophysicist who first developed the theory of the solar wind.
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The probe will be controlled from the Mission Operations Centre based at the Johns Hopkins University Applied Physics Laboratory (JHU APL), which is where NASA handles its unmanned missions.
Manned missions, such as the Apollo moon landings, were run from the Christopher C Kraft Mission Control Centre in Houston, from where it earned its famous radio call sign.