Our angry star
The Sun interacts with the Solar System in many different ways
magnetic structures than near the Earth. “In particular, we believe that the gamma-ray emission is produced several hundred kilometres deep within the Sun’s photosphere, which is a region that’s particularly hard to probe,” Linden says.
Finally, from the photosphere we go all the way out to the Sun’s extended outer atmosphere, the corona, for the strangest features of all. The fact that the corona is up to 500-times hotter than the Sun’s surface isn’t new. The coronal heating problem has been known about since the 19th century, and many theories try to explain it. The eerie-looking corona, which can be viewed from Earth during a total solar eclipse, or by spacecraft such as NASA's Solar and Heliospheric Observatory (SOHO), is a million-times dimmer than the Sun’s surface, but because Earth’s surface atmosphere is around two billion billion-times as dense – the corona being up to only ten atoms per cubic centimetre – there’s very little heat in the corona, despite its temperature.
What hasn't been known until now is that the Corona has a hidden structure. Dr Craig DeForest from the Southwest Research Institute and his team ‘denoised’ images of the upper, cooler parts of the solar corona using NASA‘s Solar Terrestrial Relations Observatory (STEREO). He adds, “The work we did involves the corona at quite high altitudes, well above where most of the coronal heat is.” By looking at this region the team uncovered something.
“By revealing that the outer corona is very highly structured, we believe we’ve found an energy reservoir large enough to explain a related heating problem – the solar wind heating problem.” The solar wind near the Earth can be between 100,000 to 1,000,000 degrees Celsius (180,032 to 1,800,032 degrees Fahrenheit) when it should be closer to 2,500 degrees Celsius (4,532 degrees Fahrenheit). DeForest says that the most exciting thing will be seeing how this large-scale structure will compare with the fine detail that will be measured by NASA's Parker Solar Probe, which launched on 12 August.
“We believe we’ve found
an energy reservoir large enough to explain a related heating problem”
8. The outer boundsAt about 120-times the Earth-Sun distance, the solar wind stops abruptly. Detected by NASA’s Voyager 2 probe, this termination shock is considered the start of interstellar space. 5. Shine bright like a flare Solar flares are bursts of electromagnetic activity that may be accompanied by coronal mass ejections. If one occurs in a coronal hole there’s nothing to stop the material firing into space. 7. Cause a conundrumAs the closest planet to theSun, Mercury’s orbit can’t be explained by Newton’s physics. It takes Einstein's general theory of relativity to offer a solution. 3. Mangled magnetic mix The Sun’s magnetic field traps plasma, but can also contort until it ‘snaps’, sending charged material flying into space as a coronal mass ejection. This causes aurorae.
6. WindsweptA constant stream of supersonic, charged particles from the corona – the solar wind – gives comets their tails, and once eroded away Mars's atmosphere. 2. Source of all lifeThe Sun, as a stable source of heat and light, keeps Earth’s oceans liquid and makes the vast majority of life possible (the exception being life around deep sea vents). 1. Know your placeThe Sun’s heat initially determined what types of planets formed and where. Rocky planets like Earth are close by, while gaseous ones like Jupiter (made of volatile molecules) are more distant. 4. There’s a hole in my outermost layerThin regions of the solar corona, with open magnetic lines, look black in X-rays, looking like 'holes'. These coronal holes let ionised material stream out into space.
Data from Fermi showed an unusual pattern of gamma-ray emissions produced by the Sun