Sun
Images May Help Solve Mystery
By MALCOLM RITTER=
AP Science Writer
02:38 PM ET 09/26/00
NEW YORK (AP) - New,
detailed images of the fiery arches of gas in the
sun's outer atmosphere might help solve a decades-old
mystery: How can the atmosphere be so much hotter than
the sun's surface?
The images released
Tuesday by the National Aeronautics and Space
Administration don't reveal the answer, but experts
say they do overturn one longstanding idea about where
the heating takes place.
Scientists have
known for decades that the outer atmosphere, called
the corona, is heated to around 3 million degrees -
much hotter than the visible surface of the sun, which
is only about 10,000 degrees.
Researchers also
knew that the corona contains millions of arches of
extremely hot gas reaching up from the surface as far
as 200,000 miles, but that didn't tell them where the
heat was coming from. The standard belief was that the
coronal loops were being heated all along their
lengths.
Not so, according to
the new ultraviolet light images from NASA's
Transition Region and Coronal Explorer spacecraft. The
images indicate the heat is being applied near the
bottom of the arches, within about 10,000 miles the
sun's visible surface. The source of that heat remains
a mystery, but knowing the location should help
scientists figure it out.
``It gives us some
kind of handle as to what might be going on,'' said
Spiro Antiochos of the Naval Research Laboratory in
Washington, D.C., who is familiar with the results.
``This is brand new information .... It is very
important.''
The images show the
arches in great detail, somewhat like revealing
individual trees where scientists had only seen a
forest. They show that each arch is actually a bundle
of thin, individual strands of gas.
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