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.
| 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) |
History
editLarge 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
editOne 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
editAnother 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
editIn 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
editReferences
edit- ^ 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
- ^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
- ^ "Sun's 'quiet period' explained". BBC News. 13 August 2010. Retrieved 20 October 2024.
- ^ "SIDC Monthly Smoothed Sunspot Number".
- ^ "Spotless Days".
- ^ Dr. Tony Phillips (11 July 2008). "What's Wrong with the Sun? (Nothing)". NASA. Archived from the original on 14 July 2008.
- ^ "Solaemon's Spotless Days Page".
- ^ "Brushfires in the Sky". nasa.gov. 25 April 2000. Retrieved 18 November 2010.
- ^ "Minor Damage Reported from Geomagnetic Storm" (PDF). Retrieved 2 January 2021.
- ^ "A Solar Radiation Storm". nasa.gov. 14 July 2000. Archived from the original on 24 June 2021. Retrieved 18 November 2010.
- ^ "Hotshot". nasa.gov. Retrieved 18 November 2010.
- ^ "Hotshot". nasa.gov. Retrieved 18 November 2010.
- ^ "Biggest ever solar flare was even bigger than thought". spaceref.com. 15 March 2004. Retrieved 18 November 2010.
External links
edit- "The Most Powerful Solar Flares Ever Recorded". spaceweather.com. Retrieved 18 November 2010.
