Sunspots are the most prominent feature associated with the sun.
The Chinese Chronicles documented numerous sightings of dark spots on the sun's face long before the inventions of the telescope. These were seen when the sun's light is significantly dimmed by clouds or haze, particularly around sunrise and sunset. These dark areas were often called "flying bird" by the Chinese.
Galileo was blinded by the sun in 1610 when he looked through his crude telescope. His eyesight was permanently impaired. He came up with a solution. He dimmed the room and placed his telescope at the shutter of the window. The image of the Sun was projected onto a sheet. This allowed him to capture the image and was able then to track the sunspots' path. They moved around the sun's disk for several days, disappearing at one end and reappearing at the other. Evidently, the sun was moving on the same axis as Earth.
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Scientists have discovered that the sun rotates faster at the equator than near the poles. This is based on observations of sunspots. It takes 25 days to complete one full turn, whereas it takes 29 days close by the poles.
Contrast
Initial impressions of sunspots are dark, sculpted holes in the face of the sun. The temperature at the photosphere's surface is approximately 11,000 F (6,100 C). A sunspot, however, is much cooler at 8,000 F (4.400 C). Because it is cooler than the rest of the area, the spot appears darker.
However, it is clear that if you were able to lift a sunspot from the sun's surface, and then place it in the sky, it would shine as bright as a hundred full Moons!
A sunspot's umbra is a dark, irregularly-shaped center that can be approximately 900 miles (1.400 km) wide and over 50,000 miles (80,000km) in diameter. The umbra is enclosed by a smaller, more dark area known as a penumbra. This can increase the size of the sunspot and make it more difficult for more than 20 Earths to disappear. They swim in pairs or in clusters through the sea of incandescent gas; they then slow down and decline.
Magnetic tempests
Astronomers have been studying sunspots over hundreds of years. However, it is not known what caused them. These spots have strong magnetic fields, and they can be seen as giant solar storms. This could be due to deeper, more frequent changes. Richard C. Carrington, an English astronomer, was charting sunspots every day on Sept. 1, 1859. His telescope's solar image was filtered to decrease its blinding brightness. But suddenly, in one sunspot group, two bright spots of light appeared.
Carrington initially thought that there was a gap between his filter and the sun, but then the spots got brighter. Carrington was the first to see a solar flare, a rapid release of energy that causes hot gases to rise from the surface of sunlight. In a matter of minutes, the magnetic needles at every observation station around the globe began to gyrate in a wild dance.
Since then, there has been a strong correlation between sunspots and solar flares. The likelihood of big flares is higher if there are more spots. The aurora borealis or northern lights is a bright, colorful display of diffuse shifting and glowing light that can be seen in space shortly after a flare explodes.
The majority of auroral displays are found in the arctic region around Earth's magnetic poles. However, on rare occasions, a large sunspot/solar flare can push their visibility zone through Canada and into the central or southern United States. Carrington witnessed a flare that caused the northern lights in the Caribbean to reach as far south as the Caribbean. These magnetic disturbances can also cause surges of electricity to enter the Earth's atmosphere. This can disrupt radio communications and cause utility companies circuit breakers trip, cutting off power. In March 1989, a similar outburst shut down power in Quebec, Canada for nine hours.
Cyclical spottiness
Heinrich Schwabe, a German scientist who discovered the solar cycles, was the one who did it. In 1825, Heinrich Schwabe of Dessau, Germany, began daily observations of the sun in the hopes of finding a planet in the orbit of Mercury. Schwabe didn't find the planet, but he did draw the sun's disk 17 years ago, keeping track of all dots and spots, small or large, on every sunny day. Gradually Schwabe noticed a distinct cycle: an 11-year span of decreasing and increasing sunspot activity. Since then, every possible aspect of life has been linked to the 11 year sunspot cycle. This includes the stock market, wars and epidemics, as well as the price of whiskey.
Are sunspots affecting our weather?
Scientists believe so. Two astronomers Edward Maunder (late 19th century) published papers that suggested that there was a time period in the 1715-1745 years when sunspots were extremely rare. This 70-year period coincided, interestingly, with the middle of the "Little Ice Age", during which Europe and North America experienced significantly colder temperatures than average.
Astronomers have noticed that the sun has been going through unusually long periods without sunspots over the past decade. Even at the latest solar maximum in 2014, the sunspot number was 36% lower than normal. Many believe we are heading towards another extended sunspot minimum similar to that of 375 years ago. This could lead to another spell of unusually cold temperatures, which some call "global cooling".
However, many environmental scientists strongly disagree. They believe that the Little Ice Age of the late 17th and early-18th centuries was likely due to an unusually high level volcanic activity, which emitted large amounts of ash and dust into our atmosphere. NASA states that aerosol clouds functioned as an atmospheric shade, reducing the amount of sunlight entering the atmosphere, and this was the primary cause of the Little Ice Age.
It is still a contentious matter.
New tool to forecast solar energy
The Space Environment Center was renamed the Space Weather Prediction Center in 2007. It recently added a brand new space weather forecast model to its toolbox to enhance forecast capabilities and protect the U.S. against space weather hazards.
The Whole Atmosphere Model - Ionosphere Plasmasphere Elektrodynamics (WAMIPE) space weather forecast tool will help predict the Earth's response to solar and geomagnetic thunderstorms. It will also predict the total electron content, which is crucial for navigation and communication systems. The new neutral density field product can be used to aid satellite operators and ground tracking system ground trackers in their orbit prediction and space situational awareness.
You can view the latest output of the model through Space Weather Prediction Center's (SWPC) website.
Jake Bleacher (chief scientist, NASA's Human Exploration and Operations Mission Directorate), stated that there is no bad weather. "Space weather is what our job is to prepare for."
Forecasts that are not in line with reality
The end of the solar activity cycle number 25 signaled that it had reached its lowest point in December 2019. Current expectations are that the maximum will be reached around mid-2025. However, even with this expectation, not all solar scientists agree on how strong it will become. Solar cycle 25 will have a slow start, but peak with sunspot ranges of 95 to 130. This is a significant decrease from the usual 140-220 sunspots per solarcycle.
A forecast published in Solar Physics, November 2020, showed the exact opposite. It predicted that Sunspot Solar Cycle 25 would have a magnitude comparable to the highest since records began.
It seems that we will have to wait to see what happens in the months and years ahead. Even if the solar cycle is below average, it doesn't mean that there's no chance of extreme space weather. "The sun's effect on our daily lives, is real, and it is there. SWPC is open 24/7/365 because the sun can always give us something to predict," Doug Biesecker (a solar physicist at Space Weather Prediction Center), noted.
Joe Rao is an instructor at the Hayden Planetarium in New York. He is a writer on astronomy for Natural History magazine and the Farmers' Almanac, among other publications. Follow us on Facebook and Twitter @Spacedotcom
