Although scientists have discovered that Sun‘s atmosphere is so much hotter than its surface long ago, they couldn’t show any strong evidence of that statement. But now, scientists at NASA has produced a strongest evidence that explains why the Sun’s atmosphere is several hundred times hotter than its surface.
The Sun is the star at the center of the Solar System. It has a diameter of about 1,392,684 km (865,374 mile), around 109 times that of Earth, and its mass (1.989×1030 kilograms, approximately 330,000 times the mass of Earth) accounts for about 99.86% of the total mass of the Solar System.
The Sun’s surface is called “Photosphere.” It has a temperature of around 5,505 °C (9,941 °F). But the Sun’s external atmosphere known as Corona regularly reaches temperatures of several million degrees Celsius.
In order to find an acceptable and a logical explanation of such huge difference of temperature, NASA launched a rocket towards the Sun in April 2013. The rocket was equipped with a super-sensitive spectrograph, which could gather information about what material is present at any given temperature based on the light it emits.
However, scientists looked at six minutes of data from the rocket, which is designed to record a snapshot of the solar atmosphere once every 1.3 seconds. The rocket scanned one of the ‘active regions’ of the Sun – which are special, highly magnetic regions where sunspots, solar flares and coronal mass ejections are common occurrences – for light emissions.
As light from this active region streamed into the rocket’s spectrograph, the instrument separated it into various wavelengths. The wavelengths were plotted out on what’s known as an emission line, which allowed the researchers to identify the atoms present in the region. From this, they identified the presence of material with a temperature of 10 million degrees Celsius.
According to NASA scientists, this report is “the strongest evidence “that tiny nanoflares “heat the plasma up 10 million degrees to keep the corona hotter than the Sun’s surface.” The team has published the results in the Astrophysical Journal, and you can watch a video about the discovery below: