Solar cycle 23
{{Infobox Solar cycles
|image=Sun with sunspots.JPG
|caption=The Sun, with some sunspots visible, during solar cycle 23 (2003)
|cycle_num=23
|start_date=August 1996
|end_date=December 2008
|duration=12.3
|max_count=180.3
|max_count_date=November 2001
|min_count=11.2
|spotless_count=817
|prev_name=Solar cycle 22
|next_name=Solar cycle 24
|prev_dates=1986–1996
|next_dates=2008–late 2019
}}
File:SSN Predict NASA.gif 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.{{citation|doi=10.1023/A:1014296529097|year=2002|last1=Kane|first1=R.P.|title=Some Implications Using the Group Sunspot Number Reconstruction|journal=Solar Physics|volume=205|issue=2|pages=383–401|bibcode=2002SoPh..205..383K}}{{cite web | title=The Sun: Did You Say the Sun Has Spots? | url=http://www.spacetoday.org/SolSys/Sun/Sunspots.html | publisher=Space Today Online | accessdate=12 August 2010}} The solar cycle lasted 12.6 years,{{cite news|url=https://www.bbc.com/news/science-environment-10967292|title=Sun's 'quiet period' explained|date=13 August 2010|work=BBC News|access-date=20 October 2024}} 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.{{cite web |title=SIDC Monthly Smoothed Sunspot Number |url=http://sidc.oma.be/sunspot-data/}} During the minimum transit from solar cycle 23 to 24, there were a total of 817 days with no sunspots.{{cite web |title=Spotless Days |url=http://spaceweather.com/glossary/spotlessdays.htm?PHPSESSID=dli444kmrjgre0rjq6l86fv144}}{{cite web |url=https://science.nasa.gov/headlines/y2008/11jul_solarcycleupdate.htm|archive-url=https://web.archive.org/web/20080714032353/https://science.nasa.gov/headlines/y2008/11jul_solarcycleupdate.htm|url-status=dead|archive-date=14 July 2008|title=What's Wrong with the Sun? (Nothing)|date=11 July 2008|author=Dr. Tony Phillips|publisher=NASA}}{{cite web |title=Solaemon's Spotless Days Page |url=http://users.telenet.be/j.janssens/Spotless/Spotless.html}} 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.{{cite web |url=https://science.nasa.gov/science-news/science-at-nasa/2000/ast25apr_1m/ |title=Brushfires in the Sky |date=25 April 2000 |publisher=nasa.gov |accessdate=18 November 2010}} 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.{{cite web |url=http://www.solarstorms.org/NewsPapers/d2000b.pdf |title= Minor Damage Reported from Geomagnetic Storm|access-date=2 January 2021}} Auroras were visible as far south as Texas.{{cite web|url=https://science.nasa.gov/science-news/science-at-nasa/2000/ast14jul_2m/|title=A Solar Radiation Storm|date=14 July 2000|work=nasa.gov|access-date=November 18, 2010|archive-url=http://web.archive.org/web/20210624193028/https://science.nasa.gov/science-news/science-at-nasa/2000/ast14jul_2m/|archive-date=June 24, 2021}}
= 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.{{cite web |url=http://sohowww.nascom.nasa.gov/hotshots/2003_10_28/ |title=Hotshot |publisher=nasa.gov |accessdate=18 November 2010}} 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.{{cite web |url=http://sohowww.nascom.nasa.gov/hotshots/2003_11_04/ |title=Hotshot |publisher=nasa.gov |accessdate=18 November 2010}}{{cite web |url=http://www.spaceref.com/news/viewpr.html?pid=13844 |title=Biggest ever solar flare was even bigger than thought |date=15 March 2004 |publisher=spaceref.com |accessdate=18 November 2010}} 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
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References
{{reflist|30em}}
External links
- {{cite web |url=http://www.spaceweather.com/solarflares/topflares.html |title=The Most Powerful Solar Flares Ever Recorded |publisher=spaceweather.com |accessdate=18 November 2010}}
{{Solar cycles}}
{{Use dmy dates|date=September 2019}}
{{DEFAULTSORT:Solar Cycle 23}}