Average dimension and magnetic structure of the distant Venus magnetotail

Abstract

We report the first major statistical investigation of the far wake of an unmagnetized object embedded in the solar wind. The investigation is based on Pioneer Venus Orbiter magnetometer data from 70 crossings of the Venus wake at altitudes between 5 and 11 Venus radii during reasonably steady IMF conditions. We find that Venus has a well‐developed tail, flaring with altitude and possibly broader in the direction parallel to the IMF cross‐flow component. Tail lobe field polarities and the direction of the cross‐tail field are consistent with tail accretion from the solar wind. Average values for the cross‐tail field (2 nT) and the distant tail flux (3 MWb) indicate that most distant tail field lines close across the center of the tail and are not rooted in the Venus ionosphere. We illustrate our findings in a three‐dimensional schematic.