ocr: The whole sky seen in Lyman-alpha by the solar wind mapper SWAN. Two areas were not covered for safety reasons, one around the Sun, the other one around the anti-solar direction. The white U-shaped band are hof O and B stars in the Milky Way. The huge hydrogen clouds of comet Hyakutake in April 1996 and comet Hale-Bopp in 1997 are illuminated by solar Lyman alpha photons.
