The Solar Disc and Sunspots

We are currently experiencing a historic lull in cyclical sunspot activity that has lasted much longer than scientists expected. You can use this page to follow day-to-day sunspot developments on the Sun's surface.

The solar disc graphic comes from Space Weather. This site provides information on the solar environment with daily updates on the solar wind, x-ray solar flares and sunspots. The graph depicting the solar cycle sunspot number progression was generated by the Space Weather Prediction Center.

The Solar Disc
The solar disc...updated daily.

Sunspot cycles
Historical record of the solar sunspot cycle.

What Are Sunspots and Why Should a Weather Observer be Interested in Them?

A sunspot is a location on the sun's photosphere that is experiencing strong magnetic activity. This activity reduces convection from the sun's interior, resulting in lower surface temperatures. Although temperatures in a sunspot range from 4000 to 4500°K, this is considerably cooler that the surrounding solar material, making it visible as a dark spot.

Galileo reported seeing sunspots in 1610 shortly after viewing the sun with his new telescope. Later, in 1749, the Zurich Observatory began to make daily sunspot observations. By 1849, a number of european observatories began recording sunspots in a detailed and systematic manner.

It is often difficult to make out individual sunspots in a large grouping of sunspots. A sunspot formula has been devised to come up with a reasonable approximation of sunspot numbers.

Monthly averages of sunspot numbers indicate that they wax and wane with an approximate 11-year cycle. Periods of high activity often disrupt radio and cell phone transmissions as energized matter and photons from solar storms associated with sunspot activity bombard the earth's ionosphere and magnetic fields. These disruptions can also have a seious impact on satellite transmissions of television, telephone and GPS navigational signals.

In 1984, E. Walter Maunder noticed that very few sunspots were observed between 1645 and 1715. John A. Eddy in 1976 confirmed that the Sun had 0.1% of the usual amount of sunspot activity during the Maunder minimum. This period of solar inactivity corresponds to a climatic period called the "Little Ice Age". Winters were unusually severe in Europe during this interval and some climate researchers are convinced that there was a cause-and-effect relationship between low sunspot numbers and cold winters. However, others argue that sunspots have little or no influence on the Earth's climate. The energy output of the Sun varies very little over the 11 year solar sunspot cycle (i.e., by about 0.1%). This small change may be too small to affect the lower levels of our atmosphere where weather takes place.