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Sunspot AR3664 visible on the bottom right part of the Earth-facing side of the sun on May 9, 2024. (NASA/ Solar Dynamics Observatory) Millions of people who went out of their way to find eclipse ...
On 17 April, sunspot group 2994 released an X1.2 flare. [47] [48] However, the complex's activity subsided slightly in the next few days. [49] While crossing the solar limb, sunspot region 2992 emitted M7.3 and X2.2 flares, the latter being the strongest of the cycle up to that point. [49]
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]
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]
Reconstruction of solar activity over 11,400 years. Sunspot numbers over the past 11,400 years have been reconstructed using carbon-14 and beryllium-10 isotope ratios. [10] The level of solar activity beginning in the 1940s is exceptional – the last period of similar magnitude occurred around 9,000 years ago (during the warm Boreal period).
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 have started in 1755. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO. [1]
History of SDO patch, Facebook; Sunspot Database based on SDO (HMI) satellite observations from 2010 to nowadays with the newest data. Album of images and videos by Seán Doran, based on SDO imagery, and a longer (24 min.) YouTube video: Sun Dance; SDO 5-year timelapse video of the Sun; SDO 10-year timelapse video of the Sun
Solar minimum is the regular period of least solar activity in the Sun's 11-year solar cycle. During solar minimum, sunspot and solar flare activity diminishes, and often does not occur for days at a time. On average, the solar cycle takes about 11 years to go from one solar minimum to the next, with duration observed varying from 9 to 14 years.