The sun’s otherworldly landscape, including coronal moss, solar rain and 6,000-mile-tall spires of gas, is revealed in footage from the Solar Orbiter spacecraft.
The observations, beamed back by the European Space Agency probe, reveal feathery, hair-like structures made of plasma and also capture eruptions and showers of relatively cooler material falling to the surface.
Scientists say the observations of the sun’s complex surface dynamics could help resolve the question of why the sun’s atmosphere is so much hotter than its surface – a longstanding paradox in solar physics.
The brightest regions are about 1,000,000C, while cooler material, which dips below 10,000C, appears darker. The footage was recorded on 27 September 2023 by the Extreme-Ultraviolet Imager (EUI) instrument, when the spacecraft was roughly a third of the Earth’s distance from the sun.
The annotated video highlights delicate lace-like patterns across the sun, which is called coronal moss. These structures appear around the base of large coronal magnetic field loops. On the horizon, spires of gas, known as spicules, reach up from the sun’s chromosphere to heights of about 6,000 miles (10,000km).
In the centre of the field of view, a small eruption is visible, with cooler material being lifted upwards before mostly falling back down. Although small relative to the largest events, this eruption is still larger than Earth.
The footage also reveals coronal rain, which at less than 10,000C looks dark against the bright background of large coronal loops (about 1,000,000C). The rain is made of higher-density clumps of plasma that fall back towards the sun under the influence of gravity.
“It’s really gorgeous when you see it happening,” said Dr David Long, a solar physicist at Dublin City University and Solar Orbiter scientist. “It kind of comes and goes – you see showers of it around solar flares.”
The observations could help explain why, at more than 1,000,000C, the sun’s outer atmosphere (known as the corona) is more than 150 times hotter than its surface.
The corona would be expected to be cooler because the sun’s energy comes from the nuclear furnace in its core, and things naturally get cooler the further away they are from a heat source. One explanation is that miniature flares, called campfires, are pumping energy into the atmosphere to cause causing coronal heating.
“It’s still a bit of an open question,” said Long. “These campfires that Orbiter observed for the first time are just going off constantly.
“It’s working out how much energy they’re producing and whether it’s enough to heat the atmosphere to what we’re seeing. It’s the combination of all these different features.”
The $1.3bn (£1bn) mission was launched in 2020 and next year will begin to climb out of the planetary plane to provide the first glimpses of the sun’s uncharted north and south poles.
Source: theguardian.com
