The story “Stormy weather” carries some statements that I think need clarification: “If high-energy protons happen to strike astronauts outside the shelter of their spacecraft, they could be severely injured” or even killed. “Because the ionosphere absorbs much of the protons’ energy, they don’t pose a threat to people or electrical systems on Earth.” However, the National Oceanographic and Atmospheric Administration’s Space Weather Scales describe the biological effect of solar storms not only for the space program, but also for aviation. While for people on Earth there may not be significant biological danger, for those in aircraft, the picture is more complex. The extent of exposure of crew and passengers is a function of a number of factors including the altitude and latitude of an aircraft. Under NOAA’s scale of “Strong, Severe or Extreme” radiation-storm conditions, biological effects may be anticipated for some crew and passengers. Mardi Crane
Arlington, Vt.