"In the third year of Lothar, emperor of the Romans, in the twenty-eighth year of King Henry of the English … on Saturday, 8 December, there appeared from the morning right up to the evening two black spheres against the sun," Worcester wrote.Ī page from Thomas Harriot's notebook. The earliest known drawings of solar activity appeared many years later, in 1128, in John of Worcester's chronicle. However, there are no known early illustrations of such observations. Chinese and Korean astronomers frequently observed sunspots, according to the Chandra X-ray Center. According to the Chandra X-ray Center, the earliest records of solar activity are from Chinese astronomers around 800 B.C. There is some debate about who discovered sunspots. To see what sunspots look like today, check out this observing page from the Solar and Heliospheric Observatory (SOHO). The sun is experiencing solar cycle 25, in which solar activity is currently on the rise, resulting in a greater emergence of sunspots. This period of severely reduced solar activity came to be known as the "Maunder minimum," after British astronomer Edward Walter Maunder, who - along with his wife, Annie - discovered the lack of activity from the records in 1890, according to The Times. For comparison, during a "normal" solar minimum there are usually 12 to more than 100 sunspots per year. Between 16, fewer than 50 sunspots were recorded, according to Physics World. Though the 11-year solar cycle is fairly consistent, between 16, very few sunspots were observed. Sunspots and the solar cycleĭuring solar maximum a large number of sunspots are visible at mid-latitudes and during solar minimum a very small number (sometimes zero) of sunspots are visible at the equator. Then a few years later, the poles start to flip again, everything gets reconfigured, and the number of sunspots starts to to dwindle once more. Once the flip completes, then there is a good few (4-5 years, sometimes more, sometime less) of stable global magnetic field and during that time it is much easier for more bigger sunspots to form. During that flip (it takes about a year to complete the flip), the magnetic field throughout the sun is reconfiguring itself, and so sunspots are very rare. The sun flips its magnetic poles every 11 years or so (north becomes south, and south becomes north). Why are there sunspot minimums and maximums? In terms of confirmation by telescope (so beginning around 1600), there are independent cases to be made for Galileo, Thomas Harriot, Christoph Scheiner and Johannes Fabricius, among many others. There are records of dark features on the sun, as observed by eye, in ancient writings (some in ancient Chinese texts all the way back to 400 BC). It's very hard to give a definitive answer. This magnetic field partially blocks some energy from getting though the surface.Īnd so the temperature at the surface is actually lower for sunspots than for other parts of the surface.Ī lower temperatures means it appears darker. The sunspots are large concentrations of strong magnetic field. James McAteer is a Professor of Astronomy at New Mexico State University and Director of the Sunspot Solar Observatory. We asked Dr James McAteer a few commonly asked questions about sunspots. According to the University Corporation for Atmospheric Research (UCAR), if you could cut out a standard sunspot from the sun and place it in the night sky, it would appear as bright as a full moon. The strong magnetic field inhibits the influx of hot, new gas from the sun's interior, causing sunspots to be cooler and appear darker than their surroundings, relatively speaking. The magnetic field in active sunspot regions can be some 2,500 times stronger than Earth's, according to the NWS. A group of sunspots is known as an active region. This disturbance in the sun's magnetic field forms pores that can grow and join together to form larger pores, or proto-spots, that eventually become sunspots. Eventually, the magnetic fields "snap," rise and break the surface. Sunspots are, on average, about the same size as Earth, though they can vary from hundreds to tens of thousands of miles across, according to Cool Cosmos.Īs the sun rotates, these magnetic loop "rubber bands" get more wound up (both tighter and more complicated).
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