The temperature of the Sun’s surface is 5500º C. But the solar corona, which lies about 2,000 km above the surface, rages at a few million degrees celsius. We don’t know why.
These images from February 24, 2014, show the first moments of an X-class flare in different wavelengths of light – seen as the bright spot that appears on the left limb of the Sun. Hot solar material can be seen hovering above the active region in the sun’s atmosphere, the corona. The images were captured by the Solar Dynamics Observatory. Caption and credit: gsfc/Flickr, CC BY 2.0
Sarah Iqbal is a senior research fellow at the department of biochemistry, Aligarh Muslim University, India.
The Sun’s atmosphere is hotter than its surface, and physicists have been baffled by this for seven decades. Nuclear fusion occurring at the Sun’s core produce all the star’s heat and light. So scientists naturally assumed that the surface closer to the core would be hotter. However, while the temperature of the photosphere – the starstuff that sits around the core – measures 5500º C, the solar corona, which lies about 2,000 km above the surface, rages at few million degrees celsius.
“This is against ...