Major sunspots photographed by NASA's Solar Dynamics Observatory spacecraft.
(Image Sources: NASA, Wikipedia.org, By NASA - http://www.dailymail.co.uk/sciencetech/article-2042428/Best-auroras-seen-Britain-thanks-huge-solar-flares.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=16800815)
By Glenn A. Walsh
Reporting for SpaceWatchtower
Will the Sun continue to propagate weak solar activity, or will the Sun suddenly become much more active, affecting the Northern Lights, radio reception, orbiting satellites, and the power grid?
Last September, NASA and the National Oceanic and Atmospheric Administration (NOAA) announced that a new 11-year sunspot cycle had begun on the Sun, and this cycle would likely be as weak as the previous cycle. However, in December, a new report issued by the National Center for Atmospheric Research (NCAR) contradicts the September report arguing that the new solar cycle could be one of the strongest in history!
Sunspots, which have been observed on other stars (hence, known as star-spots) in addition to our Sun, are complex and temporary phenomena caused by the twisting of magnetic fields in the photosphere of the Sun. They usually come in pairs, with each having an opposite magnetic polarity. Sunspots appear as black or gray spots on the Sun because they are cooler than the rest of the photosphere.
But, sunspots are far from cold.
Sunspots measure +4,892 to +7,592 degrees Fahrenheit / +2,700 to
+4,200 degrees Celsius, while the rest of the Sun's photosphere
usually has a temperature around +9,932 degrees Fahrenheit / +5,500
degrees Celsius. Hence, by comparison, sunspots appear black or gray because they are cooler.
When viewed on the surface of the Sun, sunspots appear as a black spot, known as the umbra, often surrounded by a gray area known as the penumbra. Great care must be taken when attempting to view sunspots, as eye-sight could be damaged if proper precautions are not taken anytime you look directly at the Sun. Galileo, who first used a telescope to view sunspots, was not aware of the danger, and his eye-sight suffered as a consequence.
Many people use special filters on telescopes to observe sunspots. These filters are safe, so long as they are from a well-respected telescope vendor, are specifically designed for solar observing, and are undamaged. Further, only use solar filters that are placed over the telescope objective (where the Sun-light enters the telescope). Solar filters produced many years ago, that are installed at the eye-piece of the telescope, are very dangerous and can fail, as the strength of the magnified Sun-light cracks the filter, allowing unfiltered Sun-light to enter a person's eye.
The best way to observe sunspots is to project the image of the Sun from a telescope onto a projection screen, where people can safely see the sunspots on the projection screen. From 1941 to 1991, this method was used to show the public sunspots, using the rather unique 10-inch Siderostat-type Refractor Telescope, at Pittsburgh's original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center).
Scientists now believe that Solar Cycle
24 ended in December of 2019. It takes several months to confirm the
ending of a solar cycle, hence scientists did not announce this until
September. Solar magnetic North and South Poles change or "flip" magnetic polarity as a solar cycle changes.
Solar Cycle 24 peaked in April of 2014, after beginning in 2011. While, on average, a sunspot cycle runs for 11 years, Solar Cycle 24 was also one of the shortest, running for less than 9 years.
Only a total of 116 sunspots were counted during that short time period, making Solar Cycle 24 one of the weakest in memory. Further, in 2019 there were more than 281 days (77 per-cent of the year) when the side of the Sun facing Earth had no sunspots at all! It has been more than a century since we have observed that long of a period without sunspots.
In September, NASA and NOAA predicted that the new Solar Cycle 25 would only have a total of 115 sunspots. However, NCAR scientists claim solar and sunspot activity could come roaring back during the new cycle, with sunspots totaling between 210 and 260! They note that the last time there was a 9-year cycle, in the 1950s, was followed by Solar Cycle 19, one of the strongest in the 20th century.
In a mathematical analysis, looking at 270 years of sunspot records (since 1755), NCAR determined that the shorter one solar cycle is, the greater the chance that the following solar cycle will be much stronger. This study, “Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude,” was published in the 2020 November 24 issue of the peer-reviewed journal Solar Physics.
If the new NCAR hypothesis turns-out to be true, this would be strong evidence supporting the NCAR theory that the 11-year sunspot cycle is produced by overlapping 22-year magnetic cycles on the Sun. From a series of papers published over the last decade, NCAR has been promoting this new theory. They believe that a better understanding of this 22-year Hale Cycle could lead to a more accurate prediction of the timing and nature of sunspot cycles.
NCAR Deputy Director and solar physicist Scott McIntosh told NCAR and UCAR News:
“Scientists have struggled to predict both the length and the strength of sunspot cycles because we lack a fundamental understanding of the mechanism that drives the cycle. If our forecast proves correct, we will have evidence that our framework for understanding the sun’s internal magnetic machine is on the right path.”
Study co-author Bob Leamon, a researcher at the University of Maryland Baltimore County adds:
“When we look back over the 270-year long observational record of terminator events, we see that the longer the time between terminators, the weaker the next cycle. And, conversely, the shorter the time between terminators, the stronger the next solar cycle is.”
In his previous works, Dr. McIntosh has found that magnetic field bands, which wrap around the Sun as part of the extended 22-year solar cycle, migrate from high latitudes toward the solar equator over a 20-year or-so period. As these magnetic field bands cross the mid-latitudes, often sunspots emerge. When these magnetic field bands, which have opposite polarities in the Northern and Southern Hemispheres, meet and destroy each other at the equator, a new magnetic cycle and a new sunspot cycle begin.
The National Science Foundation, NCAR's sponsor, and NASA's Living With a Star Program supported this new research.
Internet Links to Additional Information ---
Sunspots: Link >>> https://en.wikipedia.org/wiki/Sunspot
Solar Phenomena: Link >>> https://en.wikipedia.org/wiki/Solar_phenomena
Earth's Sun: Link >>> https://en.wikipedia.org/wiki/Sun
Additional Information Regarding NCAR Hypothesis:
NASA: Link >>> https://www.nasa.gov/
NOAA: Link >>> https://www.noaa.gov/
NCAR: Link >>> https://ncar.ucar.edu/
Related Blog-Posts ---
"Strong Solar Flare Seen, Although Approaching Sunspot Minimum." Sat., 2017 July 15.
"Largest Sunspot in 24 Years Returns for 2nd Month." Sun., 2014 Nov. 23.
Wednesday, 2021 February 10.
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Glenn A. Walsh, Informal Science Educator &
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Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>> http://www.planetarium.cc Buhl Observatory: Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc