Most Recent Solar Max Information

The 11 Year Sunspot Cycle

A sunspot is a cooler and darker spot that appears periodically on the Sun’s photosphere (the Sun’s surface); it is a product of magnetism. Sunspots often appear in groups and posses a specific magnetic polarity that indicate electromagnetic origins. In fact, the making of a sunspot is due to a strong magnetic field that inhibits the transport of heat through convective motion (movement of molecules) in the Sun, which makes it cooler and darker than the surrounding area. The magnetic field forms below the Sun's surface, generated by the Sun’s inner fusion dynamics, and extends out into the Sun's corona. And, if you ask how big are sunspots, some are as big as a planet.

The average length of solar max occurs in 11 year cycles. The German Astronomer Samuel Heinrich Schwabe first discovered this cycle in 1843. However, the length of the cycle varies; some have been as short at 9 years and some as long as 14. The most recent solar max occurred in 2001 and it was cycle number 23. One thing of interest here is that on January 2008, cycle number 24 started, but cycle number 23 had not ended.This occurred due the fact that a high-latitude, reversed-polarity sunspot appeared, and this typically signals the start of a Solar Cycle.

The Sunspot Number

You compute the "sunspot number" by counting the number of sunspot groups and then the number of individual sunspots. On average, most sunspot groups contain ten spots, so the formula for counting sunspots delivers reliable numbers even if the observing conditions are less than ideal.

In 1848, a Swiss astronomer named Rudolf Wolf came up with a way to count sunspots. The sunspot count using Wolf's formula, is known as the Wolf sunspot number, and it is in use today. It is also known as the daily "Boulder Sunspot Number."

The formula is R = k(10g +s ) where s is the number of individual spots, g is the number of sunspot groups, and k is a factor that varies with location. Wolf used data from earlier astronomers to reconstruct sunspot counts as far back as the 1755-1766 cycle, which he called "cycle 1".

The second sunspot number is the International sunspot number. It too uses the same Wolf formula. The Boulder number is typically 25% higher than the International sunspot number. The difference is that they incorporate data from different astronomical observatories.

The Maunder Minimum

Part of the reason to study Sunspots is to see what effect they have on Earth's weather. Early records of sunspots indicate that the Sun went through a period of inactivity in the late 17th century from about 1645 to 1715, also known as the Maunder Minimum (recognized by astronomer E. H. Maunder in 1890). Astronomers saw very few sunspots, and this result is well-known and documented. Consequently, this period of solar inactivity corresponds to a climatic period known as the "Little Ice Age" when frozen rivers appeared that were normally ice-free in the winter and snow fields appeared year-round at lower altitudes.

The Butterfly Diagram

Since 1874, the Royal Greenwich Observatory has made observations of sunspots. They include information on the sizes and positions of sunspots as well as their numbers. The interesting thing that developed is that the data shows that sunspots do not appear at random over the surface of the Sun. Instead, they are concentrated in two latitude bands on either side of the equator. A butterfly diagram shows the positions of the spots for each rotation of the Sun since May 1874. It shows that these bands first form at mid-latitudes in the Sun, then widen, and finally move toward the equator as each cycle progresses.

Sources

Science-News Author Unknown, https://science.nasa.gov/science-news/science-at-nasa/2006/10mar_stormwarning/

https://www.dailymail.co.uk/sciencetech/article-1300874/Solar-tsunami-First-picture-Sun-middle-storm.html

The 11-year Sunspot cycle

Image https://www.exploratorium.edu/sunspots/research4.html (Website contains the image)

"The Sunspot Cycle" https://www.windows2universe.org/sun/activity/sunspot_cycle.html (Website contains image).

The Sunspot Number

Windows to the Universe, "The Sunspot Number," Author Unknown: https://spaceweather.com/glossary/sunspotnumber.html ("Image courtesy of Windows to the Universe").

Nasa Science News, "Solar Cycle 24 Begins", Author Dr. Tony Phillips, https://science.nasa.gov/science-news/science-at-nasa/2008/10jan_solarcycle24/

The Maunder Minimum

Maunder Minimum, Author Jeffery Hall, https://science.jrank.org/pages/4184/Maunder-Minimum.html