Nanodust particles in the interplanetary medium
Dust particles smaller than about a wavelength of light are abundant in our solar system, created by collisions between asteroids and from the evaporation of comets. As they scatter sunlight, these particles produce the zodiacal light, the glow in the night sky that stretches along the zodiac. The zodiacal light is most easily seen after sunset or before sunrise, though it is faint enough that even moonlight can mask it. Nanodust particles are about ten times smaller than normal dust—too small to efficiently scatter sunlight. They can be sensed by spacecraft, however, because when they impact the spacecraft they generate puffs of ionized gas and electrical pulses that instruments can detect. The Solar TErrestrial RElations Observatory (STEREO) spacecraft has been detecting nanodust pulses since its launch in 2007, and previous studies of these events have confirmed the general picture that these tiny particles are an important constituent of the solar...