When the Sun rises on the Moon after two weeks of lunar night, the dust begins to stir. This dust storm stretches right across the Moon at the terminator (the line between day and night), from pole to pole. An instrument left by the Apollo astronauts to detect micrometeorite impacts first spotted this strange phenomenon. It could be that the night side of the Moon is negatively charged, and the day side is positively charged. As the terminator shifts across the Moon, it picks up the dust and shifts it sideways.