Sunspots - The Solar Cycle, Sunspots And Weather, Why Sunspots Are Dark, Causes
spots time period
Sunspots are relatively dark, temporary spots that appear on the Sun from time to time. The largest of these spots are visible to the naked eye and have been noted by Chinese astronomers since antiquity, but their first mention in Western literature is in The Starry Messenger (1610) by Italian astronomer Galileo Galilei (1564–1642). Sunspot activity—the number of spots on the Sun at any one time—varies with a period of 11–13 years. This corresponds to the period of an overall solar-activity cycle whose other features include solar flares and prominences.
Additional Topics
At the beginning of an active period in the solar cycle, a few sunspots appear at the higher latitudes (i.e., near the poles). These are more or less stationary on the Sun's surface, but appear to us to move because of the Sun's axial rotation. Large spots—which may be large enough to sink many Earths in—may last for one or several solar-rotation periods of about a mont…
One suggestion of a sunspot-weather link comes from historical records. There was a curious period of about 75 years shortly after Galileo's discovery of sunspots when few were observed. This era is called the Maunder minimum after the astronomer who first noted its existence. Other phenomena such as the aurora borealis (northern lights) that are associated with solar activity are also miss…
The strong magnetic field in a sunspot, which is several thousand times stronger than that at the surface of the earth, accounts for the relative dimness of the spot. The hot atmosphere of the Sun contains a significant number of atoms having a net positive charge resulting from collisions between them (i.e., they are ionized, having each lost one or more electrons). Moving charged particles tend …
In the second half of the twentieth century a mechanism of sunspot formation was proposed which accounts for much of their observed behavior. To begin with, the Sun does not rotate as a rigid body; the polar regions rotate somewhat more slowly than the equator. (The reason for this is still not known.) Because the solar material is electrically charged, the Sun's overall magnetic field is d…
Citing this material
Please include a link to this page if you have found this material useful for research or writing a related article. Content on this website is from high-quality, licensed material originally published in print form. You can always be sure you're reading unbiased, factual, and accurate information.
Highlight the text below, right-click, and select “copy”. Paste the link into your website, email, or any other HTML document.
User Comments