The Uranian system - An overview

Results of many years of observations from the ground and from the Voyager encounter with Venus are presented which clarify a number of issues that were subjects of speculation or partial information. The new issues that the encounter brought to light are outlined. The encounter revealed additional rings, extensive dust associated with them, and complexities, including azimuthal asymmetries. Uranus possesses a strong (about 1 gauss) magnetic field with a bizarre geometry that can be described as a dipole offset 0.3 RU from the center of the planet and tilted approximately 60 deg with respect to the axis of rotation. It is argued that it is produced by a magnetohydrodynamic dynamo at about 0.4 RU from the planet's center. It is inferred from this that at least part of the interior is a convective fluid, indicating an adiabatic temperature profile and a warm interior. The magnetic field produces a magnetosphere with some peculiar characteristics, owing to the unique orientation of the dipole axis with respect to the direction of the solar wind flow.