Observations of comet C/1999 S4 (LINEAR) with the Chandra satellite in 2000 determined that X-rays observed from that comet were produced predominantly by charge exchange collisions between highly charged carbon oxygen and nitrogen minor ions in the solar wind, and neutral water, oxygen and hydrogen in the comet's coma.
1999 | 1999 in music | Space: 1999 | The Mummy (1999 film) | 1999 in film | 1999 Pan American Games | 1999 ATP Tour | 1999 ICF Canoe Slalom World Championships | Ontario general election, 1999 | 1999 World Championships in Athletics | 1999 Rugby World Cup | House of Lords Act 1999 | 1999 Cricket World Cup | 1999 Copa América | 1999 in sports | Woodstock 1999 | New South Wales state election, 1999 | Malaysian general election, 1999 | Athletics at the 1999 Pan American Games | 1999 WTA Tier I Series | 1999 in literature | 1999 IAAF World Indoor Championships | Three Kings (1999 film) | 1999 in television | 1999 24 Hours of Le Mans | Tarzan (1999 film) | New Zealand general election, 1999 | Life (1999 film) | FIFA Women's World Cup 1999 | Eurovision Song Contest 1999 |