All Topics  
Solar flare

 
Solar Flare

   Email Print
   Bookmark   Link






 

Solar flare



 
 
A solar flare is a violent explosion in a star's (like the Sun
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
's) atmosphere releasing as much energy
Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
 as 6 × 1025 Joule
Joule

The joule is the SI derived unit of energy in the International System of Units. It is defined as:One joule is the amount of energy required to perform the following actions:...
s. Solar flares affect all layers of the solar atmosphere (photosphere
Photosphere

The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, f???- f?t??/photos meaning "light" and sfa????/sphairos meaning "ball," in reference to the fact that it is a ball-shaped surface perceived to emit light....
, corona
Corona

A corona is a type of Plasma "celestial body's 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....
, and chromosphere
Chromosphere

The chromosphere is a thin layer of the Sun's celestial body's atmosphere just above the photosphere, roughly 2,000 kilometers deep. The chromosphere is more visually transparent than the photosphere....
), heating plasma
Plasma (physics)

In physics and chemistry, plasma is a partially ionized gas, in which a certain proportion of electrons are free rather than being bound to an atom or molecule....
 to tens of million Kelvin
Kelvin

The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero ....
 and accelerating electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s, proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
s and heavier ion
Ion

An ion is an atom or molecule which has lost or gained one or more electrons, giving it a positive or negative electrical charge. According to the Bohr_model this will be from or in the outer shield 'n'....
s to near the speed of light
Speed of light

The speed of light in an free space is an important physical constant usually written as c, with a value of 299,792,458 metres per second....
. They produced radiation
Electromagnetic radiation

Electromagnetic radiation takes the form of wave propagation waves in a vacuum or in matter. EM radiation has an electric field and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy Wave propagation....
 across the electromagnetic spectrum
Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible electromagnetic radiation frequencies. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation from that particular object....
 at all wavelength
Wavelength

In physics, wavelength is the distance between repeating units of a propagating wave of a given frequency. It is commonly designated by the Greek language letter lambda ....
s, from radio waves
Radio frequency

Radio frequency is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves....
 to gamma ray
Gamma ray

Gamma rays are a form of electromagnetic radiation produced by atom particle interactions, such as electron-positron annihilation or radioactive decay....
s. Most flares occur in active regions around sunspot
Sunspot

A sunspot is a region on the Sun's surface that is marked by intense magnetism activity, which inhibits convection, forming areas of reduced surface temperature....
s, where intense magnetic fields penetrate the photosphere
Photosphere

The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, f???- f?t??/photos meaning "light" and sfa????/sphairos meaning "ball," in reference to the fact that it is a ball-shaped surface perceived to emit light....
 to link the corona
Corona

A corona is a type of Plasma "celestial body's 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....
 to the solar interior
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona.

X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere
Ionosphere

The ionosphere is the uppermost part of the Earth's atmosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere....
 and disrupt long-range radio communications.






Discussion
Ask a question about 'Solar flare'
Start a new discussion about 'Solar flare'
Answer questions from other users
Full Discussion Forum



Encyclopedia


A solar flare is a violent explosion in a star's (like the Sun
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
's) atmosphere releasing as much energy
Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
 as 6 × 1025 Joule
Joule

The joule is the SI derived unit of energy in the International System of Units. It is defined as:One joule is the amount of energy required to perform the following actions:...
s. Solar flares affect all layers of the solar atmosphere (photosphere
Photosphere

The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, f???- f?t??/photos meaning "light" and sfa????/sphairos meaning "ball," in reference to the fact that it is a ball-shaped surface perceived to emit light....
, corona
Corona

A corona is a type of Plasma "celestial body's 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....
, and chromosphere
Chromosphere

The chromosphere is a thin layer of the Sun's celestial body's atmosphere just above the photosphere, roughly 2,000 kilometers deep. The chromosphere is more visually transparent than the photosphere....
), heating plasma
Plasma (physics)

In physics and chemistry, plasma is a partially ionized gas, in which a certain proportion of electrons are free rather than being bound to an atom or molecule....
 to tens of million Kelvin
Kelvin

The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero ....
 and accelerating electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s, proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
s and heavier ion
Ion

An ion is an atom or molecule which has lost or gained one or more electrons, giving it a positive or negative electrical charge. According to the Bohr_model this will be from or in the outer shield 'n'....
s to near the speed of light
Speed of light

The speed of light in an free space is an important physical constant usually written as c, with a value of 299,792,458 metres per second....
. They produced radiation
Electromagnetic radiation

Electromagnetic radiation takes the form of wave propagation waves in a vacuum or in matter. EM radiation has an electric field and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy Wave propagation....
 across the electromagnetic spectrum
Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible electromagnetic radiation frequencies. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation from that particular object....
 at all wavelength
Wavelength

In physics, wavelength is the distance between repeating units of a propagating wave of a given frequency. It is commonly designated by the Greek language letter lambda ....
s, from radio waves
Radio frequency

Radio frequency is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves....
 to gamma ray
Gamma ray

Gamma rays are a form of electromagnetic radiation produced by atom particle interactions, such as electron-positron annihilation or radioactive decay....
s. Most flares occur in active regions around sunspot
Sunspot

A sunspot is a region on the Sun's surface that is marked by intense magnetism activity, which inhibits convection, forming areas of reduced surface temperature....
s, where intense magnetic fields penetrate the photosphere
Photosphere

The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, f???- f?t??/photos meaning "light" and sfa????/sphairos meaning "ball," in reference to the fact that it is a ball-shaped surface perceived to emit light....
 to link the corona
Corona

A corona is a type of Plasma "celestial body's 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....
 to the solar interior
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona.

X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere
Ionosphere

The ionosphere is the uppermost part of the Earth's atmosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere....
 and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb operation of radars and other devices operating at these frequencies.

Solar flares were first observed on the Sun by Richard Christopher Carrington
Richard Christopher Carrington

Richard Christopher Carrington was an England amateur astronomer whose 1859 astronomical observations first corraborated the existence of solar flares as well as their electrical influence upon the Electric Earth and its aurora ; and whose 1863 records of sunspot observations demonstrated differential rotation in the Sun....
 and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within 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
Solar cycle

The solar cycle, or the solar magnetic activity cycle, is the main source of periodic solar variation driving variations in space weather....
). At the peak of the cycle there are typically more sunspots on the Sun, and hence more solar flares.

Classification of flares

Solar flares are a fierce explosion in a stars atmosphere, which release enormous amounts of energy. Solar flares have an effect on all of the layers of the star and have the power to heat plasma to tens of millions of Kelvin and accelerate protons, neutrons and electrons to almost the exact speed of light. They bring forth radiation across the electromagnetic spectrum at all types of wavelengths. Flares are powered by the discharge of magnetic energy from the corona of the star. Rays that are emitted from solar flares can have a great effect on the Earth’s ionosphere and cut off long range communications. When the sun is active, it can have several solar flares, and when it is quiet, it will not have one for over the range of a week.

Hazards


Solar flares and associated Coronal Mass Ejection
Coronal mass ejection

A coronal mass ejection is an ejection of material from the Sun corona, usually observed with a white-light coronagraph.The ejected material is a Plasma consisting primarily of electrons and protons , plus the entraining coronal magnetic field....
s (CMEs) strongly influence our local space weather
Space weather

Space weather is the concept of changing environmental conditions in outer space. It is distinct from the concept of weather within a Celestial body atmosphere, and deals with phenomena involving ambient Plasma , magnetic fields, radiation and other matter in space....
. They produce streams of highly energetic particles in the solar wind
Solar wind

The solar wind is a Electric current—a Plasma —ejected from the stellar atmosphere of the sun. It consists mostly of electrons and protons with energies of about 1 electron volt....
 and the Earth's magnetosphere
Magnetosphere

A magnetosphere is a highly magnetized region around and possessed by an astronomical object. Earth is surrounded by a magnetosphere, as are the magnetized planets Mercury , Jupiter, Saturn, Uranus, and Neptune....
 that can present radiation
Radiation

In physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body....
 hazards to spacecraft and astronauts. The soft X-ray
X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequency in the range 30 Hertz to 30 Hertz and energies in the range 120 Electron volt to 120 keV....
 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.

Solar flares release a cascade of high energy particles known as a proton storm. Protons can pass through the human body, doing biochemical
Biochemistry

Biochemistry is the study of the chemistry processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
 damage. 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, taking only 15 minutes after observation to reach Earth, indicating a velocity of approximately one-third light speed.

The radiation risk posted by solar flares and CMEs is one of the major concerns in discussions of manned missions
Manned mission to Mars

A human mission to visit and land on the planet Mars has long been a subject for science fiction writers and a dream of space exploration advocates. Though various mission proposals have been put forth by multiple space agency for such a mission, the logistical and financial obstacles are considerable, and many critics contend that such a mission...
 to Mars or to the moon or any other planets. 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.

Flare Observations

The following missions have flares as their main observation target.

  • Yohkoh
    Yohkoh

    Yohkoh , known before launch as Solar-A, was a Sun observatory spacecraft of the Japan Aerospace Exploration Agency with NASA and PPARC collaboration....
     - The Yohkoh (originally Solar A) spacecraft observed the Sun with a variety of instruments from its launch in 1991 until its failure in 2001. The observations spanned a period from one solar maximum to the next. Two instruments of particular use for flare observations were the Soft X-ray Telescope (SXT), a glancing incidence low energy X-ray telescope for photon energies of order 1 keV, and the Hard X-ray Telescope (HXT), a collimation counting instrument which produced images in higher energy X-rays (15-92 keV) by image synthesis.


  • GOES
    Goes

    Goes is a municipality and a city in the southwestern Netherlands in Zuid-Beveland, in the province Zeeland. The city of Goes consists of approximately 27,000 civilians....
     - The GOES spacecraft have measured the soft X-ray flux from the Sun since the mid 1970s, following the use of similar instruments on the satellites. The GOES X-ray observations are commonly used to classify flares, with A, B, C, M, and X representing different powers of ten - an X-class flare has a peak 2-8 A flux above 0.1 W/m2.


  • RHESSI - RHESSI is designed to image solar flares in energetic photons from soft X rays (~3 keV) to gamma rays (up to ~20 MeV) and to provide high resolution spectroscopy up to gamma-ray energies of ~20 MeV. Furthermore, it has the capability to perform spatially resolved spectroscopy with high spectral resolution.


  • Hinode
    Hinode

    Hinode , formerly known as Solar-B, is a Japan Aerospace Exploration Agency Sun mission with United States and United Kingdom collaboration....
     - A new spacecraft, originally called Solar B, was launched by the Japan Aerospace Exploration Agency
    Japan Aerospace Exploration Agency

    The , or JAXA, is Japan national aerospace agency. JAXA was formed on October 1, 2003, as an Independent Administrative Institution through the merger of three previously independent organizations....
     in September 2006 to observe solar flares in more precise detail. Its instrumentation, supplied by an international collaboration including Norway, the U.K., and the U.S., focuses on the powerful magnetic fields thought to be the source of solar flares. Such studies shed light on the causes of this activity, possibly helping to forecast future flares and thus minimize their dangerous effects on satellites and astronauts..


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
Richard Christopher Carrington

Richard Christopher Carrington was an England amateur astronomer whose 1859 astronomical observations first corraborated the existence of solar flares as well as their electrical influence upon the Electric Earth and its aurora ; and whose 1863 records of sunspot observations demonstrated differential rotation in the Sun....
 and left a trace in Greenland
Greenland

Greenland is a member country of the Kingdom of Denmark located between the Arctic Ocean and Atlantic Oceans, east of the Canadian Arctic Archipelago....
 ice in the form of nitrate
Nitrate

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
s and beryllium
Beryllium

Beryllium is a chemical element with the symbol Be and atomic number 4.A Bivalent element, beryllium is found naturally only combined with other elements in minerals....
-10, which allow its strength to be measured today (New Scientist, 2005).

Prediction


Current methods of flare prediction are probabilistic, and there is no certain indication that an active region on the Sun will produce a flare. However, many properties of sunspots and active regions correlate with flaring. For example, magnetically complex regions (based on line of sight magnetic field) called delta spots produce most large flares. A simple scheme of sunspot classification due to McIntosh is commonly used as a starting point for flare prediction. Predictions are usually stated in terms of probabilities for occurrence of flares above M or X GOES class with 24 or 48 hours. The U.S. National Oceanic and Atmospheric Administration (NOAA) issues forecasts of this kind.

See also

  • Coronal mass ejection
    Coronal mass ejection

    A coronal mass ejection is an ejection of material from the Sun corona, usually observed with a white-light coronagraph.The ejected material is a Plasma consisting primarily of electrons and protons , plus the entraining coronal magnetic field....
  • Flare star
    Flare star

    A flare star is a variable star which can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection in the atmospheres of the stars....
  • Geomagnetic storm
    Geomagnetic storm

    A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere caused by a disturbance in space weather. Associated with solar coronal mass ejections , coronal holes, or solar flares, a geomagnetic storm is caused by a solar wind shock wave which typically strikes the Earth's magnetic field 24 to 36 hours after the event....
  • Aurora (astronomy)
    Aurora (astronomy)

    Auroras, sometimes called the northern and southern lights or aurorae , are natural light displays in the sky, usually observed at night sky, particularly in the Geographical pole....


External links

  • - D. Montes, UCM.
  • - D. Montes, UCM.
  • , lecture by Dr Stuart Clark on the discovery of solar flares given at Gresham College
    Gresham College

    File:Gresham College, 1740.jpgGresham College is an unusual institution of higher learning off Holborn in central London. It enrolls no students and grants no academic degrees....
    , 12 September 2007 (available as a video or audio download as well as a text file).
  • - NASA Astronomy Picture of the Day
    Astronomy Picture of the Day

    The Astronomy Picture of the Day website is a service provided by NASA and Michigan Technological University . According to the website, ?Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer.?...
  • An educational resource for teachers and students about the Sun and its effect on the Earth
  • NASA
    NASA

    The National Aeronautics and Space Administration is an agency of the Federal government of the United States, responsible for the nation's public list of space agencies....
     May 6 2008