Mercury,
November/December 2000 Table of Contents
A
giant torus of charged particles surrounding Jupiter gives astronomers
a chance to study a nebula up close.
by
Duane H. Pontius, Jr., Birmingham-Southern College
"Astronomers
are accustomed to a hands-off relationship with their subjects.
Even the most lovingly studied celestial objects tend to remain
remote, separated from our scientific instruments by immense stretches
of space and time. Apart from a few small rocks in our own solar
system and the lone star at its center, the multifarious denizens
of the sky remain aloof."
This
statement certainly holds true for the vast clouds of gas and dust
that astronomers call "nebulae." The closest nebulae lie hundreds
or even thousands of light-years away. But there is one exception,
a nebula that resides right here in our own solar system: the Io
plasma torus.
In
this article, Duane Pontius traces the nebula's origin to Jupiter's
volcanic moon Io. Powerful volcanic eruptions lift material into
space, where it gets trapped by Jupiter's magnetic field. The material
gets whipped around by Jupiter's rotation, forming a donut-shaped
cloud of charged particles. Pontius describes various ground-based
and spacecraft observations of the Io torus and the complex interactions
that take place within the torus. At the end of the article, Pontius
explores how studying the Io plasma torus will help astronomers
understand what's happening in more distant realms.
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