Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
Related to sunspot: Sunspot cycle


1. any of the dark cool patches, with a diameter of up to several thousand kilometres, that appear on the surface of the sun and last about a week. They occur in approximately 11-year cycles and possess a strong magnetic field
2. Austral a small cancerous spot produced by overexposure to the sun



a dark formation observed in the photosphere of the sun. The diameters of sunspots can be as large as 200,000 km, and the temperatures are not greater than 4500°K. Since the temperature of the photosphere is 1,000 to 2,000 degrees higher than that of sunspots, the photosphere is two to five times brighter than the spots. The mean annual number of sunspots varies with a period of 11 years.


Bray, R., and R. Loughhead. Solnechnye piatna. Moscow, 1967. (Translated from English.)


A dark area in the photosphere of the sun caused by a lowered surface temperature.
References in periodicals archive ?
Extreme magnitudes are calculated by considering the solar cycle data between the years 1848 and 2013 and by using the minimum sunspot numbers per cycle (s) as they are shown in Table 1.
This same sunspot group was responsible for another flare on Aug 21 reported by NOAA as C1.1 X-ray class from 11:25 UT to 11:48 UT.
As key structural elements on the surface of the Sun, sunspots and faculae provide solar physicists ample opportunity for observation and discussion.
If you buy a specialized hydrogen-alpha solar scope, you can observe a lot more than sunspots, eclipses, and the transit of Venus.
Ironically, the only way to really find out if phenomena like sunspots and solar wind are playing a larger role in climate change than most scientists now believe would be to significantly reduce our carbon emissions.
To test the SUNSpot, we set it up in a test rack alongside two other bulbs, a Standard Q4509 and a 35-watt HID system loaned to us by Knots2U, which makes one of our top-rated HID systems.
Sunspots and the increased UV radiation that come with them continue on an 11-year cycle but their overall levels haven't risen much in the past 30 years.
A comparison of the beryllium-10 data with the historical records of sunspot numbers reveals a high degree of correlation.
SUNSPOT QuickGreen Cuisine lost its director of operations to a health crisis, and one of its locations suffered from reduced access due to construction, in contrast, San Francisco's VegTime[R] got caught up in the Internet business bust, according to founder Davy Davidson.
Sunspot: As long as Ja Rule albums are for sale people are always gonna buy hip-hop.
Sunspot will be joining hundreds of exhibitors from South America to the Far East, showcasing holidays from long summer breaks and world cruises to weekends in the countryside and short city hops.
In The Sunspot Letters (1613), again, it is not just the observational technology that is new: the text is written, illustrated, and published in a format that reflects Galileo's underlying philosophy about the reader's relationship to these new kinds of observations he is making.