Solar cycle 9

{{Infobox Solar cycles

|cycle_num=9

| image = File:Fizeau Foucault-First Photo of Sun 1845.jpg

| caption = The Sun in 1845, during solar cycle 9

|start_date=July 1843

|end_date=December 1855

|duration=12.4

|max_count=219.9

|max_count_date=February 1848

|min_count=17.6

|spotless_count=655

|prev_name=Solar cycle 8

|prev_dates=1833–1843

|next_name=Solar cycle 10

|next_dates=1855–1867

}}

File:Edward Sabine 1860s.jpg and other scientists linked solar cycles to geomagnetic cycles.]]

Solar cycle 9 was the ninth solar cycle since 1755, when extensive recording of solar sunspot activity began.{{cite journal|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|s2cid=118144552 }}{{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 12.4 years, beginning in July 1843 and ending in December 1855. The maximum smoothed sunspot number observed during the solar cycle was 219.9 (February 1848), and the starting minimum was 17.6.SIDC Monthly Smoothed Sunspot Number. "[http://sidc.oma.be/sunspot-data/]" During the solar cycle minimum transit from solar cycle 9 to solar cycle 10, there were a total of 655 days with no sunspots.Spotless Days. "[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}}Solaemon's Spotless Days Page. "[http://users.telenet.be/j.janssens/Spotless/Spotless.html]"

Solar cycle 9 began in 1843, the year that Heinrich Schwabe discovered the sunspot cycle.Claudio Vita-Finzi. Solar History: An Introduction, p. 4, Springer, 2012 {{ISBN|9400742959}}. During this cycle, Edward Sabine, Rudolf Wolf, and other scientists recognized that solar disturbances affected the Earth's magnetic environment, so that solar cycles are identical to the Earth's geomagnetic cycles. Wolf also introduced the Wolf number during this period.

The phenomenon now known as geomagnetically induced current was seen for the first time during this cycle – it became apparent on the emerging electric telegraph network. Francis Ronalds, Honorary Director of the Kew Observatory and Sabine's colleague, received data from telegraph operators on the movements of their magnetic needles for comparison with his own photo-recordings of atmospheric electricity and geomagnetic intensity variations but had insufficient resources to study the causes of the unexpected currents in detail.{{Cite book|title=Sir Francis Ronalds: Father of the Electric Telegraph|last=Ronalds|first=B.F.|publisher=Imperial College Press|year=2016|isbn=978-1-78326-917-4|location=London}}{{Cite journal|last=Ronalds|first=B.F.|date=2016|title=Sir Francis Ronalds and the Electric Telegraph|journal= The International Journal for the History of Engineering & Technology|volume=86 |pages=42–55 |doi=10.1080/17581206.2015.1119481|s2cid=113256632 }}

Geomagnetic activity during solar cycle 9 followed a double-peaked distribution, with more magnetic storms during the rising (1847–48) and falling (1851–54) parts of the cycle.{{cite journal |last1=Nevanlinna |first1=H. |last2=Ketola |first2=A. |last3=Häkkinen |first3=L. |last4=Viljanen |first4=A. |last5=Ivory |first5=K. |date=23 April 1993 |title=Geomagnetic activity during solar cycle 9 (1844–1856) |journal=Geophysical Research Letters |volume=20 |issue=8 |pages=743–746 |doi=10.1029/93GL00836 |bibcode = 1993GeoRL..20..743N }}