The largest sunspots are visible to the naked eye and were followed by Chinese astronomers thousands of years ago. Energy pouring outward from the sun's core creates strong magnetic currents that ebb and flow. These areas range in size from hundreds to thousands of kilometers in diameter. Although some sunspots are large enough to view through binoculars, or even the unaided eye with proper filtering, most require a telescope. Sunspots often form in groups, with the largest spanning several Earth diameters across.
Groups typically consist of one or two larger sunspots surrounded by several smaller members.
Successful sunspot viewing depends not only upon the optical quality of equipment used, but also upon the steadiness of Earth's atmosphere. Observers can lessen atmospheric interference by setting up telescopes in a grassy yard or field rather than a parking lot. Sudden, intense brightenings of the chromosphere or upper corona allow blasts of radiation to leap outward into the solar system. Randy Tatum Sunspot Cycles Sunspot numbers fluctuate within the sunspot cycle. When the cycle nears sunspot minimum, the solar disk can appear completely barren.