The closest-ever images taken of the sun have revealed mini solar flares called “campfires” dotted across its surface.
The images were captured last month by the Solar Orbiter, a European Space Agency (ESA) probe designed and built in the UK. Scientists say the pictures could shed light on the mysterious process that means the outer layer of the star is so much hotter than the layers below.
The spacecraft came within 47 million miles of the sun’s surface and passed between the orbits of Venus and Mercury.
David Berghmans from the Royal Observatory of Belgium said: “When the first images came the first thought was this is not possible, they cannot be that good, it was really much better than what we dared to hope for.”
Solar flares are sudden flashes 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”.
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.”
The mystery of why the Sun’s corona is so hot has been a mystery for years.
ESA's Solar Orbiter project scientist Daniel Müller: “The Sun’s corona is a little counter-intuitive because you would think if you had a body that was relatively cool at the centre it would be even cooler the further you go away but on the contrary, we have a hot core, a relatively cool surface of just about 5,500 degrees surrounded by a super hot atmosphere of more than a million degrees.”
The operation was a joint venture between the ESA and NASA.
“In mid-June, Solar Orbiter made its first close pass of the Sun following its Feb 9 launch, turning on all 10 of its instruments together for the first time,” NASA said in a statement on its website.
After launching on 9 February, Solar Orbiter made its first close pass of the sun in mid-June, despite the team facing setbacks due to the coronavirus pandemic.
As the spacecraft entered a critical stage of the mission in March, the ESA was forced to close operation centres that had vital measuring equipment and send staff home as the continent went into lockdown.
José Luis Pellón Bailón, Solar Orbiter Deputy Spacecraft Operations Manager at ESA said the whole team were worried for the mission when the lockdown began.
Bailón said “we had to stop the commission for almost 10 days and replan everything,” but he added, “it was challenging but we made it work.”
The images will be the closest images of the sun ever captured. "We have never taken pictures of the Sun from a closer distance than this," Müller said.
"There have been higher resolution close-ups, e.g. taken by the four-meter Daniel K. Inouye Solar Telescope in Hawaii earlier this year. But from Earth, with the atmosphere between the telescope and the sun, you can only see a small part of the solar spectrum that you can see from space."
Scientists now hope to find out more by monitoring the temperatures of these campfires using an instrument on the spacecraft known as Spectral Imaging of the Coronal Environment, or SPICE.
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.
They hope to be able to eventually make predictions on space weather much like we already do so on Earth.
Severe solar activity has the potential to damage satellites in orbit and disrupt the infrastructure on Earth that mobile phones, transport, GPS signals and the electricity networks rely on.
Dr Harper added: “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.
The images revealed today were taken more than twice the distance away from the final destination of the spacecraft.
When the spacecraft is in place it will begin to move towards the Sun’s poles, an area never seen by scientists before.
Sami Solanki, director of the Max Planck Institute for Solar System Research, said: “There will be a lot new of things to learn from the solar poles, one of the things that excites me the most is we know the magnetic field is responsible for all the activity the sun produces but we don’t know how the magnetic field itself is produced.
“But we do know that the poles play in a key role there.”
The Solar Orbiter was constructed by Airbus in Stevenage and blasted off from Nasa’s Cape Canaveral site in Florida on February 10.
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.
Dr Harper said: “It is really quite exciting to be involved (in the mission).
“We have leading roles on four of the 10 scientific instruments on board the Solar Orbiter.
“For me, it showcases the UK’s world-leading role in solar physics research and its capabilities in the industrial space sector.”