Scientists are planning a new mission to travel closer to the Sun than ever before.
The American space agency NASA says its Solar Probe Plus spacecraft will launch in 2018 and fly to within 6.5-million kilometres of the Sun's visible surface.
Astronomers hope to find out why our local star's outer atmosphere is millions of degrees hotter than its 6000°C surface temperature.
They'll also try and work out what actually generates the stream of charged particles, called the solar wind, which causes the space weather that impacts the Earth and baths the entire solar system.
The unprecedented project will involve a car-sized spacecraft plunging directly into the Sun's atmosphere.
Dr Dick Fisher, director of NASA's Heliophysics Division in Washington says: "Scientists have been struggling with these questions for decades and this mission should finally provide the answers."
To withstand the 1400°C temperatures and intense radiation during its final approach, the spacecraft will use a specially developed carbon-composite heat shield.
Finding the answers
Five science experiments aboard the probe will help scientists to better understand, characterise and forecast the Sun's radiation environment.
These include the Solar Wind Electrons Alphas and Protons Investigation, which will count the electrons, protons and helium ions that make up the most abundant particles in the solar wind. It will also try to catch a few and measure their properties.
Then there's the Wide-field Imager, a telescope capable of making 3D images of the Sun's corona or atmosphere. It will also image the solar wind and shocks as they approach and pass the spacecraft.
The Fields Experiment will make direct measurements of electric and magnetic fields, radio emissions, and shock waves that course through the sun's atmospheric plasma. It will also serve as a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna.
Finally there's ISIS, the Integrated Science Investigation of the Sun, which actually consists of two instruments designed to monitor electrons, protons and ions which accelerate to high energies in the sun's atmosphere.