A solar probe built by the European Space Agency and NASA has delivered the closest photos ever taken of the Sun's surface.
The images reveal a landscape rife with thousands of tiny solar flares that scientists dubbed "campfires".
They offer clues about the extreme heat of the outermost part of its atmosphere.
The images were captured last month by the Solar Orbiter when it came within 47 million miles of the Sun's surface.
The close pass, known as a perihelion, put the spacecraft between the orbits of Venus and Mercury.
Solar flares are brief eruptions of high-energy radiation from the Sun's surface, which can cause radio and magnetic disturbances on the Earth.
Dr Caroline Harper, head of space science at the UK space agency, said that scientists were excited by the presence of campfires that are "millions of times smaller than the solar flares".
#SolarOrbiter has made its first close pass by the Sun, studying our star and space with a comprehensive suite of instruments — and the data is already revealing previously unseen details. This is #TheSunUpClose. https://t.co/rVMjz45DoY pic.twitter.com/YLKBXRNQZb
— NASA Sun & Space (@NASASun) July 16, 2020
She said: "We do not really know what they (the campfires) are doing but there is speculation that they might play a role in coronal heating, a mysterious process whereby the outer layer of the Sun, known as the corona, is much hotter (around 300 times) than the layers below.
"These campfires may be contributing to that in a way we do not know yet."
To find out more, scientists will monitor the temperatures of these campfires using an instrument on the spacecraft known as Spectral Imaging of the Coronal Environment, or SPICE.
Aside from helping unlock the mysteries of coronal heating, the Solar Orbiter will also help scientists piece together the Sun's atmospheric layers and analyse the solar wind, the stream of highly energetic particles emitted by the star.
Understanding more about solar activity could also help scientists make predictions on space weather events, which can damage satellites in orbit and disrupt the infrastructure on Earth that mobile phones, transport, GPS signals and the electricity networks rely on.
Dr Harper said: "The science will allow us to start improving our operational capability to predict the space weather, just like you predict the weather here on Earth."
The spacecraft will make a close approach to the Sun every five months, and at its closest will only be 26 million miles away, closer than the planet Mercury.
It will use the gravitational force of Venus and Earth to adjust its trajectory, before getting into operational orbit in November 2021.
Dr Harper said: "At that point, it will send back much more data about the Sun's surface.
"It will also be flying over the poles of the Sun and take images."
The Solar Orbiter was constructed by Airbus in Stevenage in England and blasted off from Nasa's Cape Canaveral site in Florida on 10 February.
It has been designed to withstand the scorching heat from the Sun that will hit one side, while maintaining freezing temperatures on the other side of the spacecraft as the orbit keeps it in shadow.
Additional reporting Reuters
