Cycles of the Sun
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Updated June 01, 2013
The activity of our star knows a cycle of 11.2 years on average which can vary from 9.5 to 12.5 years.
The solar cycle is due to variation of internal magnetic field of the Sun.
It goes through a solar maximum, for which spots, coronal mass ejections and flares are the most frequent, to go to a minimum, where all these activities are at their lowest.
The last solar minimum occurred in 1997 and 2007, while the last maximum was in 2001.
The first recorded solar cycle is the cycle of years 1755 to 1766. The cycle ends in 2007, is number 23 (as labeled). It is Heinrich Schwabe (1789-1875) who discovered this cycle by observing the appearance of stains. The solar cycle has an important effect on the state of the ionosphere as it modifies the conditions of propagation of radio waves.
It also modifies the warming of Earth's atmosphere.
In association with the 11-year cycle, there is also a cycle of 22 years during which the polarity of the field reversed with each new cycle of 11 years.
It attributes many other rings from the Sun but more complex to determine: the cycle of Gleissberg a period of 80 to 90 years, the Suess cycle of a period of 150 to 200 years, the cycle of Hallstattzeit of period of 2300 years.
Image: A complete solar cycle observed by the satellite observation of the Sun (SOHO), which celebrated its 12th anniversary launch December 7, 2007. It shows the intensity of solar activity represented by the white spots.
Violent solar flare in 2011
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The easy observation of sunspots reveals not only the sun's rotation on itself, to equator, is in 27 days but that the activity of hot and cold zones of the Sun follow a cycle.
The solar cycle is the period during which the Sun's activity varies by up to another.
In absolute terms, solar activity is regulated by a cycle of an average period of 11.2 years but the duration can vary between 8 and 15. 15 February 2011, the Sun has produced one of its most violent eruptions, class X2. This is the most violent eruption of solar cycle that began January 8, 2008.
This eruption was observed in the active region AR 1158, located in the southern hemisphere of the Sun. We see in the picture, the intense burst of electromagnetic radiation that caused the bright vertical line on the camera SDO.
Solar flares are classified into different categories, named A, B, C, M and X, as the maximum of their flow.
Each class corresponds to a solar flare with an intensity ten times higher than the previous one. Class X is most intense.
Within the same class, the number corresponds to a linear scale. A solar flare of class X2 is twice as powerful as a rash of class X1.
The most powerful solar flares have been recorded by the GOES satellite program.
Those of 16 August 1989 and that of April 2, 2001, were class X20. That of November 4, 2003, the largest ever recorded, was estimated at X28.
Image: The solar flare of February 15, 2011, as seen by the satellite SDO. The eruption was captured in this picture, in the extreme ultraviolet.
Credit: NASA / Goddard / SDO AIA Team
Table of activity of solar cycles
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Schwabe cycles are numbered from the maximum of 1761 which is the cycle No.1.
Cycle No. 23 began in May 1996 and the cycle No.24 began January 8, 2008.
X-class eruptions result in a coronal mass ejection (CME), i.e. a big puff of gas ejected into space.
About one billion tons of material have been blown to Earth.
When these coronal mass ejections (CME) propelling a huge amount of material are in the direction of the Earth they can cause considerable damage to satellites and other electrical infrastructure land.
Fortunately, the planet's magnetic shield protects us in many of these solar storms.
Table of maximum activity of solar cycles.
Image: The solar flare of February 15, 2011. This eruption of class X was also accompanied by coronal mass ejection, a giant cloud of charged particles, traveling at nearly 900 kilometers per second towards the Earth. The eruption follows that of February 13, 2011, type M and several small outbreaks of type C over the previous days.
Solar flare of December 31, 2012
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Particles created in the core of the Sun will cross all layers of the Sun, the radiative zone of 300 000 km and the convection zone, the photosphere and finally the solar atmosphere.
December 31, 2012, a massive solar flare has risen above the solar corona.
The explosion could have caused a coronal mass ejection (CME) and dispersed high energy plasma through the solar system. But a large part of the ejected matter is settled, the magnetic forces that drive the plasma flow was not sufficient to overcome the enormous gravity of our sun.
In this picture below cons, solar fire flame extends about 250,000 km above the surface.
This relatively minor eruption is about 20 times the diameter of our planet (≈ 12,756 km).
This event lasted exactly four hours and it was captured by the Solar Dynamics Observatory (SDO) of NASA.
The images are taken in extreme ultraviolet light.
Image: This event occurred four hours from 10:20 a.m. to 2:20 p.m. December 31, 2012, it was captured by the Solar Dynamics Observatory of NASA in extreme ultraviolet light. Credit: NASA / SDO