A solar flare observed by Hinode in the G-band. It can be seen as two narrow, elongated, bright structures (ribbons) over the southern part of the sunspot.

A solar flare is a violent explosion in the Sun's atmosphere releasing up to a total energy of 6.298 × 10²⁵ Joules.^[1] Solar flares take place in the solar corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating electrons, protons and heavier ions to near the speed of light. They produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays.^[2] Most flares occur in active regions around sunspots, where intense magnetic fields emerge from the Sun's surface into the corona. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (1024 × 1024 pixel, file size: 819 KB, MIME type: image/png) A solar flare (not to be mistaken with Solar Prominence) photographed by Hinode. ... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (1024 × 1024 pixel, file size: 819 KB, MIME type: image/png) A solar flare (not to be mistaken with Solar Prominence) photographed by Hinode. ... SOLAR-B Hinode (ひので, Sunrise in Japanese), formerly known as Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. ... Sol redirects here. ... The joule (IPA: or ) (symbol: J) is the SI unit of energy. ... A corona is a type of plasma atmosphere of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... The chromosphere (literally, color sphere) is a thin layer of the Suns atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). ... For other uses, see Plasma. ... For other uses, see Kelvin (disambiguation). ... For other uses, see Electron (disambiguation). ... For other uses, see Proton (disambiguation). ... This article is about the electrically charged particle. ... The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. ... Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. ... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... For other uses, see Wavelength (disambiguation). ... This article is about electromagnetic radiation. ... For other uses, see Sunspot (disambiguation). ...

X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb operation of radars and other devices operating at these frequencies. Relationship of the atmosphere and ionosphere The ionosphere is the uppermost part of the atmosphere, distinguished because it is ionized by solar radiation. ...

Solar flares were first observed on the Sun in 1859 as localized brightenings in a sunspot group. Stellar flares have also been observed on a variety of other stars.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one each week when the Sun is "quiet". Large flares are less frequent than smaller ones. Solar activity varies with an 11-year cycle (the solar cycle). At the peak of the cycle there are typically more sunspots on the Sun, and hence more solar flares. It has been suggested that this article or section be merged with Schwabe-Wolf cycle. ...

Classification of flares

Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square meter, W/m²) of 100 to 800 picometer X-rays near Earth, as measured on the GOES spacecraft. Each class has a peak flux ten times greater than the preceding one, with X class flares having a peak flux of order 10^-4 W/m². Within a class there is a linear scale from 1 to 9, so an X2 flare is twice as powerful as an X1 flare, and is four times more powerful than an M5 flare. The more powerful M and X class flares are often associated with a variety of effects on the near-Earth space environment. Although the GOES classification is commonly used to indicate the size of a flare, it is only one measure. Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Goes is a municipality and a city in the southwestern Netherlands, in Zuid-Beveland. ...

Soft X-ray light curves showing solar flares of different sizes and durations. The red curve represents the total flux in the band 1 to 8 Angstrom, and the blue curve is the flux in 0.5 to 4 Angstrom. Basically, this means that the curves represent the evolution in time of the X-ray power emitted by the Sun in two energy ranges. Each one of the numerous spikes in the curves represents a temporary increase in the emission due to a solar flare.

Two of the largest GOES flares were the X20 events (2 mW/m²) recorded on August 16, 1989 and April 2, 2001. However, these events were outshone by a flare on November 4, 2003 that was the most powerful X-ray flare ever recorded. This flare was originally classified as X28 (2.8 mW/m²). However, the GOES detectors were saturated at the peak of the flare, and it is now thought that the flare was between X40 (4.0 mW/m²) and X45 (4.5 mW/m²), based on the influence of the event on the earth's atmosphere (see [1]). The flare originated in sunspot region 10486, which is shown in the illustration above several days before the flare. Image File history File links Size of this preview: 799 × 600 pixelsFull resolution (1384 × 1039 pixel, file size: 23 KB, MIME type: image/png) Plot made by me with public domain data. ... Image File history File links Size of this preview: 799 × 600 pixelsFull resolution (1384 × 1039 pixel, file size: 23 KB, MIME type: image/png) Plot made by me with public domain data. ... is the 228th day of the year (229th in leap years) in the Gregorian calendar. ... Year 1989 (MCMLXXXIX) was a common year starting on Sunday (link displays 1989 Gregorian calendar). ... is the 92nd day of the year (93rd in leap years) in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... is the 308th day of the year (309th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ...

The most powerful flare of the last 500 years is believed to have occurred in September 1859: it was seen by British astronomer Richard Carrington and left a trace in Greenland ice in the form of nitrates and beryllium-10, which allow its strength to be measured today (New Scientist, 2005). Richard Christopher Carrington (May 26, 1826 – November 27, 1875) was an English astronomer who discovered the differential rotation of the sun by means of sunspot observations in 1863. ... Trinitrate redirects here. ... General Name, symbol, number beryllium, Be, 4 Chemical series alkaline earth metals Group, period, block 2, 2, s Appearance white-gray metallic Standard atomic weight 9. ...

Hazards

Solar flares and associated Coronal Mass Ejections (CMEs) strongly influence our local space weather. They produce streams of highly energetic particles in the solar wind and the Earth's magnetosphere that can present radiation hazards to spacecraft and astronauts. The soft X-ray flux of X class flares increases the ionisation of the upper atmosphere, which can interfere with short-wave radio communication, and can increase the drag on low orbiting satellites, leading to orbital decay. Energetic particles in the magnetosphere contribute to the aurora borealis and aurora australis. A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... Aurora australis observed by Discovery, May 1991. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... For other uses, see Radiation (disambiguation). ... Aurora borealis Polar aurorae are optical phenomena characterized by colorful displays of light in the night sky. ... Aurora borealis Polar aurorae are optical phenomena characterized by colorful displays of light in the night sky. ...

Solar flares release a cascade of high energy particles known as a proton storm. Protons can pass through the human body, doing biochemical damage^{[citation needed]}. Most proton storms take two or more hours from the time of visual detection to reach Earth. A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured^{[citation needed]}, taking only 15 minutes after observation to reach Earth, indicating a velocity of approximately one-third light speed. Biochemistry (from Greek: , bios, life and Egyptian kēme, earth[1]) is the study of the chemical processes in living organisms. ...

The radiation risk posed by solar flares and CMEs is one of the major concerns in discussions of manned missions to Mars or to the moon. Some kind of physical or magnetic shielding would be required to protect the astronauts. Originally it was thought that astronauts would have two hours time to get into shelter, but based on the January 20, 2005 event, they may have as little as 15 minutes to do so. Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...

Hinode spacecraft

Filaments surrounding a solar flare, caused by the interaction of the plasma in the Sun's atmosphere with its magnetic field. ^[3]

The new spacecraft Hinode, originally called Solar B, was launched by the Japan Aerospace Exploration Agency in September of 2006 to observe solar flares in more precise detail. The device is meant to study the powerful magnetic fields that are thought to be the source of solar flares. Hopefully this will shed light on what exactly causes this activity, so that scientists might be able to forecast future flares and help minimize damage to satellite equipment and astronauts. See [2]. Image File history File links Solar-filament. ... Image File history File links Solar-filament. ... For other uses, see Plasma. ... SOLAR-B Hinode (ひので, Sunrise in Japanese), formerly known as Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. ... The Japan Aerospace Exploration Agency ), or JAXA, is Japans national aerospace agency. ...

See also

• Coronal mass ejection
• Geomagnetic storm
• 1 September 1859
• Aurora (astronomy)

A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... A geomagnetic storm is a temporary disturbance of the Earths magnetosphere. ... is the 244th day of the year (245th in leap years) in the Gregorian calendar. ... Year 1859 (MDCCCLIX) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Thursday of the 12-day slower Julian calendar). ... The Aurora Borealis, or Northern Lights, shines above Bear Lake Aurora Borealis as seen over Canada at 11,000m (36,000 feet) Red and green Aurora in Fairbanks, Alaska Aurora Borealis redirects here. ...

References

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 163rd day of the year (164th in leap years) in the Gregorian calendar. ...

External links

• Solar Cycle 24 and VHF Aurora Website (www.solarcycle24.com)
• Solar Weather Site
• STEREO Spacecraft Site
• BBC report on the November 4, 2003 flare
• NASA SOHO observations of flares
• Stellar Flares - D. Montes, UCM.
• The Sun - D. Montes, UCM.
• ASC / Alliances Center for Astrophysical Thermonuclear Flashes
• 'The Sun Kings', lecture by Dr Stuart Clark on the discovery of solar flares given at Gresham College, 12th September 2007 (available as a video or audio download as well as a text file).
• An X Class Flare Region on the Sun - NASA Astronomy Picture of the Day

Sir Thomas Greshams grasshopper crest is used as a symbol of the College Gresham College is an unusual institution of higher learning off Holborn in central London. ... The Astronomy Picture of the Day (APOD) website is a service provided by NASA and MTU (Michigan Technological University). ...

References

• Superflares could kill unprotected astronauts. NewScientist.com. Retrieved on 17 June, 2005.
• Mewaldt, R.A., et al. 2005. Space weather implications of the 20 January 2005 solar energetic particle event. Joint meeting of the American Geophysical Union and the Solar Physics Division of the American Astronomical Society. May 23-27. New Orleans. Abstract.
• Solar Flares NASA Video from 2003
• Solar Flares Solar & Heliospheric Observatory Video from 2002

v • d • e The Sun
Structure	Solar core - Radiation zone - Convection zone
Atmosphere	Photosphere - Chromosphere - Transition region - Corona
Extended structure	Termination Shock - Heliosphere - Heliopause - Heliosheath - Bow Shock
Solar phenomena	Sunspots - Faculae - Granules - Supergranulation - Solar Wind - Spicules - Coronal loops - Solar Flares - Solar Prominences - Coronal Mass Ejections - Moreton Waves - Coronal Holes
Other	Solar System - Solar Variation - Solar Dynamo - Heliospheric Current Sheet - Solar Radiation - Solar Eclipse - Spectral Class: G2