dipper@utastro.UUCP (Debbie Byrd) (01/05/85)
Four spacecraft are now heading toward the boundary between the realm of the sun and interstellar space. More on the heliopause -- after this. January 5 On the Way to the Heliopause Only four spacecraft from Earth have ever gone toward the outer solar system -- toward the giant planets Jupiter, Saturn, Uranus and Neptune. The Pioneers 10 and 11, and the Voyagers 1 and 2, will also become the first craft from Earth to cross the heliopause -- the boundary between the realm of the sun and the wide open spaces of the galaxy at large. No one knows when these craft will cross the heliopause, but it should be sometime in the next decade or two. The heliopause can be imagined as a great "bubble" around the solar system, where the sun's magnetic field and ultra-thin outermost gases interact with the interstellar medium. Recently the two Voyagers detected the first possible signals from the heliopause -- radio signals that may be generated by electrons accelerated through a hot plasma of charged particles -- possibly along a shock wave where the sun's electromagnetic domain comes to an end. It's not known for certain yet whether there is such a shock wave at the heliopause. It's possible that the sun moves too slowly through interstellar space to create one. So the radio emission detected by the outbound Voyagers may come from something else -- all we know now is, it's something new. Still, the fact remains that the Pioneers and the Voyagers are now heading toward the heliopause -- where no craft from Earth have ever gone before. Scientists are waiting eagerly for what they'll find when they get there -- possibly sometime in the 1990s. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
wmartin@brl-tgr.ARPA (Will Martin ) (01/08/85)
Is the Oort Cloud inside or outside the heliopause? Or is the outer boundary of the Oort Cloud defined as the heliopause? Will Martin USENET: seismo!brl-bmd!wmartin or ARPA/MILNET: wmartin@almsa-1.ARPA