Good news for lunar astronauts who fancy a stroll. Every month brings about seven straight days of relative safety from the flux of energetic charged particles from the sun, as the moon dips through the Earth鈥檚 magnetic field.
Robert Winglee of the University of Washington, Seattle, calculated that some parts of the moon spend about a quarter of the moon鈥檚 orbit protected by Earth鈥檚 magnetosphere (Geophysical Research Letters, ). 鈥淰ery few megaelectronvolt particles would be able to reach an equatorial moon base while it鈥檚 shielded by the terrestrial magnetosphere,鈥� he says. A solar storm would still pose a risk for wandering astronauts, he adds, but there would be time to return to a shielded base.
