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Sunspot activity has been measured using the Wolf number for about 300 years. This index (also known as the Zürich number) uses both the number of sunspots and the number of sunspot groups to compensate for measurement variations. A 2003 study found that sunspots had been more frequent since the 1940s than in the previous 1150 years. [30]
One historical long-term correlation between solar activity and climate change is the 1645–1715 Maunder minimum, a period of little or no sunspot activity which partially overlapped the "Little Ice Age" during which cold weather prevailed in Europe. The Little Ice Age encompassed roughly the 16th to the 19th centuries.
Individual sunspots or groups of sunspots may last anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as they move across the surface of the Sun, with diameters ranging from 16 km (10 mi) [3] to 160,000 km (100,000 mi). [4] Larger sunspots can be visible from Earth without the aid of a telescope. [5]
"The World Set Free" is the twelfth episode of the American documentary television series Cosmos: A Spacetime Odyssey. It premiered on June 1, 2014, on Fox, and aired on June 2, 2014, on National Geographic Channel.
The monthly mean sunspot number in the northern solar hemisphere peaked in November 2011, while the southern hemisphere appears to have peaked in February 2014, reaching a peak monthly mean of 102. Subsequent months declined to around 70 (June 2014). [54] In October 2014, sunspot AR 12192 became the largest observed since 1990. [55]
The book treats historical and proxy records of climate change coinciding with the Maunder Minimum, a period from 1645 to about 1715 when sunspots became exceedingly rare. [10] From 2005 to 2015, Soon had received over $1.2 million from the fossil fuel industry, while failing to disclose that conflict of interest in most of his work. [11]
Orbit: Earth's Extraordinary Journey is a BBC documentary series presented by Kate Humble and Helen Czerski which aired in 2012. Running for three 60 minute episodes, the series focuses on Earth's orbit around the Sun and its effect on humans, the climate, and geological features.
There is, he said, a clear "divergence" between the sunspots and global temperatures after 1986, which shows that the present warming period cannot be explained by solar activity alone. [ 13 ] In 1997, Friis-Christensen and Henrik Svensmark revived suggestions of a possible link between galactic cosmic rays and global climate change assisted by ...