Context
In a recent event, the sunspot AR2929 erupted, producing a powerful M5.5-class solar flare, which has been recorded by NASA's Solar Dynamics Observatory in an extreme ultraviolet flash.
- During the flare, a pulse of X-rays ionized the top of Earth's atmosphere, causing a shortwave radio blackout around the Indian Ocean.
What is Solar flare?
- A solar flare is a tremendous explosion on the Sun that happens when energy stored in 'twisted' magnetic fields (usually above sunspots) is suddenly released.
Coronal mass ejections (CMEs)
- Solar flares are different to 'coronal mass ejections' (CMEs), which were once thought to be initiated by solar flares.
- CMEs are huge bubbles of gas threaded with magnetic field lines that are ejected from the Sun over the course of several hours.
- Although some are accompanied by flares, it is now known that most CMEs are not associated with flares.
Classification of solar flare
- Solar flares are classified into three categories according to their brightness in the x-ray wavelengths.
- X-class flares are big; they are major events that can trigger radio blackouts around the whole world and long-lasting radiation storms in the upper atmosphere.
- M-class flares are medium-sized; they generally cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow an M-class flare.
- C-class flares: Compared to X- and M-class events, C-class flares are small with few noticeable consequences here on Earth.
