Changes

==History of Observation==

==History of Observation==

Large sunspots may be visible to the naked eye, when the Sun is observed through a cloud. However it is difficult to tell if what you see through the cloud is really due to a sunspot or something else. As a result, their existence was not generally accepted until the early 1600s, when people such as [[Galileo]], Thomas Harriot, Johannes Fabricus and Christoph Scheiner began studying them.<ref name=britannica/> Later in 1843, Samuel Schwabe discovered the [[sunspot cycle]], a cycle in which the number of sunspots on the [[Sun]] periodically increases and decreases roughly every 11 years.<ref>[https://www.nasa.gov/mission_pages/sunearth/news/solarcycle-primer.html Solar Cycle Primer] from nasa.gov</ref> The exact length of this cycle varies between 8 to 14 years. As part of this cycle, other solar phenomena such as [[solar flare]]s and [[coronal mass ejection]]s also change, occurring more frequently at the sunspot maximum.

Large sunspots may be visible to the naked eye, when the Sun is observed through a cloud. However it is difficult to tell if what you see through the cloud is really due to a sunspot or something else. As a result, their existence was not generally accepted until the early 1600s, when people such as [[Galileo]], Thomas Harriot, Johannes Fabricus and Christoph Scheiner began studying them.<ref name=britannica/> Later in 1843, Samuel Schwabe discovered the [[sunspot cycle]], a cycle in which the number of sunspots on the [[Sun]] periodically increases and decreases roughly every 11 years.<ref>[https://www.nasa.gov/mission_pages/sunearth/news/solarcycle-primer.html Solar Cycle Primer] from nasa.gov</ref> The exact length of this cycle varies between 8 and 14 years. As part of this cycle, other solar phenomena such as [[solar flare]]s and [[coronal mass ejection]]s also change, occurring more frequently at the sunspot maximum.

Since then, a record of sunspots on the Sun has been produced by various people over the last couple of centuries. Their number, size and shape has been recorded. The [[Maunder Minimum]], named after Edward Walter Maunder, was a period from 1645 to 1710 in which the number of sunspots dramatically decreased.<ref>[http://galileo.rice.edu/sci/observations/sunspots.html Sunspots] from galileo.rice.edu</ref> A large sunspot in 1710 was treated as a major astronomical event. In 1860, Richard Carrington used sunspots to measure the rotation speed of the Sun at different solar [[latitude]]s and found the Sun rotated faster nearer its [[equator]].<ref name=britannica/> Sunspots are now also observed from spacecraft such as the [[Solar and Heliospheric Observatory]] (SOHO).<ref name=esa>[http://sci.esa.int/soho/28320-soho-reveals-how-sunspots-take-a-stranglehold-on-the-sun/ SOHO reveals how sunspots take a stranglehold on the Sun] from sci.esa.int</ref>

Since then, a record of sunspots on the Sun has been produced by various people over the last couple of centuries. Their number, size and shape has been recorded. The [[Maunder Minimum]], named after Edward Walter Maunder, was a period from 1645 to 1710 in which the number of sunspots dramatically decreased.<ref>[http://galileo.rice.edu/sci/observations/sunspots.html Sunspots] from galileo.rice.edu</ref> A large sunspot in 1710 was treated as a major astronomical event. In 1860, Richard Carrington used sunspots to measure the rotation speed of the Sun at different solar [[latitude]]s and found the Sun rotated faster nearer its [[equator]].<ref name=britannica/> Sunspots are now also observed from spacecraft such as the [[Solar and Heliospheric Observatory]] (SOHO).<ref name=esa>[http://sci.esa.int/soho/28320-soho-reveals-how-sunspots-take-a-stranglehold-on-the-sun/ SOHO reveals how sunspots take a stranglehold on the Sun] from sci.esa.int</ref>