Energy and charged particles from the Sun continually reach Earth’s space environment. Discover how solar radiation, solar wind, the magnetosphere, auroras, and geomagnetic storms arise through interactions between the Sun and Earth.
Telescopic observers in the late 17th century faced a Sun unlike the one recorded in most modern decades. From about 1645 to 1715, sunspots became extraordinarily rare. The familiar rise and fall of the solar cycle appeared severely weakened, producing the best-observed example of a grand solar...
Sunspots turn the Sun’s invisible magnetism into a pattern that can be counted. Their numbers rise from a quiet minimum, reach a disorderly maximum, and decline again over roughly 11 years. The timing is not clockwork: individual cycles differ in length, strength, and shape, and their peaks may be...
The name solar constant suggests a fixed quantity, but the sunlight reaching Earth is never perfectly steady. Scientists use the term for the Sun’s radiant power received by a surface held perpendicular to the rays at Earth’s mean orbital distance. A more precise name is total solar irradiance, or...