Solar cycle 23

Solar cycle 23
The Sun, with some sunspots visible, during solar cycle 23 (2003).
Sunspot data
Start date	August 1996
End date	December 2008
Duration (years)	12.3
Max count	180.3
Max count month	November 2001
Min count	11.2
Spotless days	817
Cycle chronology
Previous cycle	Solar cycle 22 (1986–1996)
Next cycle	Solar cycle 24 (2008-late 2019)

NASA sunspot number predictions for Solar cycle 23 and 24

Solar cycle 23 was the 23rd solar cycle since 1755, when extensive recording of solar sunspot activity began.[1][2] The solar cycle lasted 12.6 years,[3] beginning in August 1996 and ending in December 2008. The maximum smoothed sunspot number observed during the solar cycle was 180.3 (November 2001), and the starting minimum was 11.2.[4] During the minimum transit from solar cycle 23 to 24, there were a total of 817 days with no sunspots.[5][6][7] Compared to the last several solar cycles, it was fairly average in terms of activity.

History

Large solar flares and coronal mass ejections (CMEs) occurred on 7 September 2005 (X17), 15 April 2001 (X14.4) and 29 October 2003 (X10), with auroras visible in mid-latitudes.

2000

One of the first major aurora displays of solar cycle 23 occurred on 6 April 2000, with bright red auroras visible as far south as Florida and South Europe.[8] On 14 July 2000, the CME hurled by a X5.7 solar flare provoked an extreme (G5 level) geomagnetic storm the next day. Known as the Bastille Day event, this storm caused damage to GPS systems and some power systems.[9] Auroras were visible as far south as Texas.[10]

2001

Another major aurora display was observed on 1 April 2001, due to a coronal mass ejection hitting the Earth's magnetosphere. Auroras were observed as far south as Mexico and South Europe. A large solar flare (the second-most powerful ever recorded) occurred on 2 April 2001, an X20-class, but the blast was directed away from Earth.

2003

In late October 2003, a series of large solar flares occurred. A X17.2-class flare ejected on 28 October 2003 produced auroras visible as far south as Florida and Texas. A G5 level geomagnetic storm blasted the Earth's magnetosphere over the next two days.[11] A few days later, the largest solar flare ever measured with instruments occurred on 4 November; initially measured at X28, it was later upgraded to an X45-class.[12][13] This flare was not Earth-oriented and thus only resulted in high-latitude auroras. The whole sequence of events that occurred from 28 October to 4 November is known as the Halloween Solar Storm.

See also

• List of solar cycles

References

1. Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401, Bibcode:2002SoPh..205..383K, doi:10.1023/A:1014296529097
2. "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
3. "Sun's 'quiet period' explained". BBC News. 13 August 2010. Retrieved 20 October 2024.
4. "SIDC Monthly Smoothed Sunspot Number".
5. "Spotless Days".
6. Dr. Tony Phillips (11 July 2008). "What's Wrong with the Sun? (Nothing)". NASA. Archived from the original on 14 July 2008.
7. "Solaemon's Spotless Days Page".
8. "Brushfires in the Sky". nasa.gov. 25 April 2000. Retrieved 18 November 2010.
9. "Minor Damage Reported from Geomagnetic Storm" (PDF). Retrieved 2 January 2021.
10. "A Solar Radiation Storm". nasa.gov. 14 July 2000. Archived from the original on 24 June 2021. Retrieved 18 November 2010.
11. "Hotshot". nasa.gov. Retrieved 18 November 2010.
12. "Hotshot". nasa.gov. Retrieved 18 November 2010.
13. "Biggest ever solar flare was even bigger than thought". spaceref.com. 15 March 2004. Retrieved 18 November 2010.

External links

• "The Most Powerful Solar Flares Ever Recorded". spaceweather.com. Retrieved 18 November 2010.