Magnetized Dust Clouds Penetrating the Terrestrial Bow Shock Detected by Multiple Spacecraft

Clouds of charged nanometer dust, produced in intra-meteoroid collisions and accelerated by the magnetized solar wind, twist the interplanetary magnetic field as they are accelerated. Depending on the cloud size, minutes to hours-long perturbations are observed by interplanetary spacecraft and have been termed interplanetary field enhancements (IFEs). This dust-solar wind interaction hypothesis is supported by reconstructed magnetic field geometry using IFEs detected nearly simultaneously by multiple spacecraft. On 16 January 2018, an IFE was observed by eight spacecraft in the solar wind and later by four spacecraft in the magnetosheath, after the IFE crossed the bow shock. The post-shock magnetic field geometry differed from that in the solar wind in a way compatible with the dust cloud having interacted with the shocked solar wind. These observations of dust clouds surfing in the solar wind show us how submicron-sized interplanetary dust is transported and ultimately expelled from the solar system.