![]() An exception may lie in the earth's weather. This has led most astronomers to feel that the proper sunspot cycle should be reckoned as consisting of two 11 –13 year cycles, since two cycles must pass before conditions are duplicated and the full pattern can repeat.Īlthough there have been attempts to link the solar cycle to changes on Earth, most are still characterized as correlations (i.e., the events are associated but there is no established cause and effect relationship. However, during the following sunspot cycle the order will be reversed in both hemispheres. This order of polar progression for the leading and trailing spots is preserved throughout the entire 11 –13 year cycle. Thus, if spots-pairs formed in the northern hemisphere of the Sun have the lead spot behaving as a south magnetic pole, the leading spot of a pair formed in the southern hemisphere will have north magnetic pole. The order of polarity is reversed for sunspot-pairs formed in the opposite hemisphere. During a particular cycle, the leading spot of the pair will always have the same polarity for spots formed in a particular hemisphere. Similarly, each of the members of a sunspot pair will have the characteristics of either a north or south magnetic pole. The ends of the bar magnet are characterized as being north or south magnetic poles depending on how a magnetic compass is affected by the poles. Just as a bar-magnet placed under a sheet of paper will show a characteristic looping magnetic field when iron filings are scattered over the paper, so the sunspots making up the pair appear to be connected by a similar field. The end of the cycle is marked by a marked drop in the number of low-latitude sunspots, which is followed immediately by the beginning of the next cycle, as small numbers of spots begin to appear at high latitudes.Īstronomers now know that sunspots are essentially magnetic storms on the surface of the Sun. As the cycle progresses the number of spots increases and they tend to be formed at lower latitudes toward the equator. Large spots may last for several rotation periods of about a month in length. The sunspots then appear to move across the face of the Sun due to its rotation. This corresponds to the period of solar activity cycle involving solar flares, prominences and other phenomena associated with the outer layers of the Sun.Īt the beginning of the solar cycle a few sunspots appear at the higher latitudes on the Sun near the poles. Astronomers have found that the frequency of sunspots varies with a period of between 11 and 13 years. Sunspot occurrence has been carefully noted by astronomers ever since. ![]() The first specific mention of sunspots in modern scientific literature was by Italian astronomer and physicist Galileo Galilei (1564 –1642) in his Starry Messenger published in 1610. Large sunspots, visible to the naked eye, were noted by the ancient Chinese. Variations in the solar magnetic field impact the space environment of Earth (sometime termed "space weather" and therefore have at least a correlated effect on Earth's weather and climatic conditions. Sunspots occur in cycles and are associated with a strong solar magnetic field. Although very hot by any terrestrial standard, sunspot regions are cooler that surrounding solar surface. A sunspot is an area of the Sun's photosphere, appearing darker to the eye than surrounding areas of the Sun.
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