Miniature flares that scientists are calling “campfires” dot the surface of the sun in the first images returned to Earth by the $1.5bn Solar Orbiter spacecraft.
The pictures, released by the European Space Agency on Thursday, give astrophysicists the closest view they have had of the sun. They were taken from 77m km away, a point halfway between Earth and its parent star.
The campfires are millions of times smaller than the large solar flares that can be observed from Earth.
David Long, a Solar Orbiter researcher at University College London, said they “might play an important role in a mysterious phenomenon called coronal heating, whereby the sun’s outer layer, or corona, is 200-500 times hotter than the layers below”.
The corona is the outermost layer of the sun’s atmosphere, extending millions of kilometres into space. Its temperature reaches 1m degrees centigrade, while the solar surface is just 5,500C.
Solar Orbiter is a partnership between Esa and its US counterpart Nasa, which launched the UK-built spacecraft from Cape Canaveral last February. The mission is designed to last for seven years, during which the craft and its 10 scientific instruments will follow an oval orbit coming as close as 42m km to the sun.
During this period the sun will become more active as the longstanding but still mysterious 11-year solar cycle proceeds.
One objective of the mission is to discover more about the conditions that trigger vast explosions of energy and particles from the sun. If these “coronal mass ejections” reach Earth, they can cause geomagnetic storms destabilising electric grids and telecoms networks.