Study of solar irradiance variations holds key to climate questions



This article is part of a series in Eos that investigates issues in space physics and aeronomy.

In 1838, the French physicist Claude Pouillet published the first measurement of the Sun's total light and heat input to the Earth. He described his new instrument—the pyrheliometer—and the corrections he made for attenuation of solar light in the Parisian atmosphere. Similar measurements were carried out by the English astronomer Sir John Herschel, working at about the same time at the Cape of Good Hope.