Disclaimer: Copyright infringement not intended.

Context

• The High Energy L1 OrbitingX-ray Spectrometer (HEL1OS) payload, on board the Aditya-L1 spacecraft, has captured the first glimpse of solar flares.

Details

About Solar Flares

• A solar flare is an intense localized eruption of electromagnetic radiation in the Sun's atmosphere.
• Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other solar phenomena.
• Solar flares occur in a power-law spectrum of magnitudes; an energy release of typically 1020 joules of energy suffices to produce a clearly observable event, while a major event can emit up to 1025 joules.
• Solar flares affect all layers of the solar atmosphere (photosphere, chromosphere, and corona).
• The plasma medium is heated to tens of millions of kelvins, while electrons, protons, and heavier ions are accelerated to near the speed of light.
• Flares produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays.
• Most of the energy is spread over frequencies outside the visual range; the majority of the flares are not visible to the naked eye and must be observed with special instruments.
• Flares occur in active regions often around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior.
• Flares are powered by the sudden release of magnetic energy stored in the corona.
• The same energy releases may produce coronal mass ejections (CMEs), although the relationship between CMEs and flares is still not well understood.
• The frequency of occurrence of solar flares varies with the 11-year solar cycle.
• It can range from several per day during solar maximum to less than one every week during solar minimum.
• Additionally, more powerful flares are less frequent than weaker ones.

Impact of Solar Flares and CMEs on Earth

Not all solar flares reach Earth, but solar flares/storms, solar energetic particles (SEPs), high-speed solar winds, and coronal mass ejections (CMEs) that come close can impact space weather in near-Earth space and the upper atmosphere.

• Space-dependent services: Solar storms can hit operations of space-dependent services like global positioning systems (GPS), radio, and satellite communications.
• Radio communication: Geomagnetic storms interfere with high-frequency radio communications and GPS navigation systems.
• Magnetosphere: CMEs, with ejectiles loaded with matter traveling at millions of miles an hour, can potentially create disturbances in the magnetosphere, the protective shield surrounding the Earth.
• Astronauts: Astronauts on spacewalks face health risks from possible exposure to solar radiation outside the Earth’s protective atmosphere.
• Other: Aircraft flights, power grids, and space exploration programs are vulnerable.

Categories

• There are five categories of solar flare according to their brightness in the x-ray wavelengths which include A, B, C, M, and X; each class is at least ten times more potent than the one before it.
• X-class Flares (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 (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.
• The smallest ones are A-class (near background levels), followed by other flares.

Download PDF