Solar cycle 2 was the second
solar cycle
The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...
since 1755, when extensive recording of
sunspot activity began.
The solar cycle lasted 9 years, beginning in June 1766 and ending in June 1775. The maximum
smoothed sunspot number
The Wolf number (also known as the relative sunspot number or Zürich number) is a quantity that measures the number of sunspots and groups of sunspots present on the surface of the Sun.
History
Astronomers have been observing the Sun recordin ...
observed during the solar cycle was 193.0 (September 1769), and the starting minimum was 18.6.
[SIDC Monthly Smoothed Sunspot Number.]
Sunspot observations by
Alexander Wilson (astronomer), Alexander Wilson during this period established the
Wilson effect
In astronomy, the Wilson effect is the perceived depression of a sunspot's umbra, or center, in the Sun's photosphere. The magnitude of the depression is difficult to determine, but may be as large as 1,000 km.
Sunspots result from the blockag ...
.
See also
*
List of solar cycles Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to start in 1755 when Rudolf Wolf began extensive reportin ...
References
{{DEFAULTSORT:Solar Cycle 02
2