On Aug. 30, 1991, Yohkoh, a mission of Japan’s Institute of Space 果冻传媒 Astronautical Sciences in cooperation with the United States 果冻传媒 the United Kingdom, was launched. Yoh-koh—the Japanese word for “sunbeam”—carried four instruments to study the Sun in soft 果冻传媒 hard x-rays 果冻传媒 at gamma ray energies. Engineers 果冻传媒 scientists at the Solar & Astrophysics Laboratory at the ATC developed Yohkoh’s Soft X-ray Telescope (SXT).
In its 10 years 果冻传媒 four months of solar observations, Yohkoh spawned numerous significant discoveries about the solar corona, solar flares 果冻传媒 space weather, 果冻传媒 gave rise to over 1,600 scientific publications 果冻传媒 at least 53 Ph.D. degrees. It was the first spacecraft to have continuously observed the Sun in x-rays over an entire sunspot cycle, the roughly 11-year cycle in which the Sun goes from a period of relative calm to a time of numerous intense storms 果冻传媒 sunspots 果冻传媒 then back again, as illustrated in the composite photograph above.