A solar flare is an intense burst of radiation coming from the release of magnetic energy associated with sunspots.
In other words, 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.
Image Credit: European Space Agency: A Solar Eruption
- A solar flare or solar limb is a sudden brightening observed over the Sun’s surface. It is a large energy release of up to 6 × 1025 joules of energy.
- Solar flares are thought to occur when stored magnetic energy in the Sun’s atmosphere accelerates charged particles in the surrounding plasma. This results in the emission of electromagnetic radiation across the electromagnetic spectrum.
- Solar flares affect all layers of the solar atmosphere such as the photosphere, chromosphere, and corona.
- Solar flares produce radiation across the electromagnetic spectrum at all wavelengths from radio waves to gamma rays.
- Flares occur in active regions and are often, but not always, accompanied by Coronal Mass Ejections (CME).
- X-rays and UV radiation that is released by solar flares can affect Earth’s ionosphere because these high energy radiation is absorbed by the ionosphere leading to ionization of the ionosphere which may interfere with short-wave radio communication. . Because of this, radio communications, radars and other devices may be disrupted for a short time.
Coronal Mass Ejections (CMEs)
Coronal mass ejections (CMEs) are large expulsions of plasma and magnetic field from the sun’s atmosphere — the corona.
Compared to solar flares — bursts of electromagnetic radiation that travel at the speed of light, reaching Earth in just over 8 minutes — CMEs travel at a more leisurely pace, relatively speaking.
Image Credit: Space.com
- 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.
- If a CME collides with the Earth, it can excite a geomagnetic storm. Large geomagnetic storms have, among other things, caused electrical power outages and damaged communications satellites.
- The energetic particles driven along by CMEs can be damaging to both electronic equipment and astronauts or passengers in high-flying aircraft.
- Sunspots are areas where the magnetic field is about 2,500 times stronger than Earth’s, much higher than anywhere else on the Sun. Because of the strong magnetic field, the magnetic pressure increases while the surrounding atmospheric pressure decreases.
- A sunspot is an area of high magnetic activity, on the surface of the Sun. Sunspots produce bright light, but not as much as the surface around them, so they appear dark by comparison. They are cooler than the rest of the sun. Some are small, and some are ten times bigger than Earth.
- Sunspots are phenomena in the Sun’s photosphere.
- Solar cycles last typically about eleven years. Over the solar cycle, sunspot populations increase quickly and then decrease more slowly. The point of highest sunspot activity during a cycle is known as solar maximum, and the point of lowest activity as solar minimum.
- Effect on earth: If there were more sunspots, the Earth might become hotter, and there could be less rain. Also, solar activity (and the solar cycle) have been implicated as a factor in global warming. The first possible example of this is the Maunder Minimum period of low sunspot activity which occurred during the Little Ice Age in Europe.