dipper@utastro.UUCP (Debbie Byrd) (08/24/85)
The first encounter of a spacecraft with the outer planet Uranus is less than half a year away. More -- after this. August 24 Five Months to Uranus Just five months from today, Voyager 2 will make an historic encounter -- the first encounter of a spacecraft with the planet Uranus. One question about Uranus concerns a possible magnetic field. No one knows whether Uranus has a magnetic field, though some theories and observations suggest that it does. Voyager 2 has already been listening for radio signals from Uranus -- which would be strong evidence for a magnetic field. When it gets there, Voyager will probe Uranus with a magnetometer -- a device for detecting and measuring such a field. The magnetic field of Uranus -- if it exists -- might be expected to behave differently from that of Earth, or any other world. Although the origins of magnetic fields aren't very well understood, the fields are thought to be generated from within the core of a planet as it spins on its axis. And Uranus spins sideways compared to the Earth and other planets. Its axis of rotation lies nearly flat in the plane of the solar system. What's more, the north pole of the uranian axis of rotation is now pointing almost directly toward the sun. The solar wind -- streams of charged particles from the sun -- could be pouring straight down the magnetic pole of Uranus -- perhaps adding to uranian versions of radiation belts -- something like the Van Allen belts surrounding our Earth. No one knows if Uranus has a magnetic field -- or how it may behave. It's a mystery that'll be solved -- when Voyager 2 encounters Uranus just five months from today. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin