What causes a solar flare?
Solar flares originate from highly complex and unstable strong magnetic fields that arc out over sunspots. Flares are driven by the so-called magnetic reconnection process between oppositepolarity magnetic fields. The magnetic field lines can meet, fuse and also break apart to create new connections.
During the reconnection process, the released magnetic energy is converted into kinetic energy, thermal energy and particle acceleration that manifests in a burst of radiation across a wide range of the electromagnetic spectrum, from radio waves, through optical emission to X-rays and gamma rays.
Solar flares erupt outwards with speeds of up to a few million miles an hour, releasing massive amounts of energy. This can be equivalent to millions of nuclear bombs exploding simultaneously. Flares are categorised according to their brightness in X-ray wavelengths. The most powerful eruptions are X-class flares, which can trigger radio blackouts on Earth, and result in long-lasting radiation storms in Earth’s upper atmosphere. An M-class flare is about ten times weaker than an X-class one. These flares could cause brief radio blackouts that affect only Earth’s polar regions. The X- and M-class flares are often accompanied by coronal mass ejections (CMEs) that hurl enormous clouds of superheated plasma into space. Compared to X- and M-class events, C-, B- and A-classes are small, without any noticeable
consequences on Earth.