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W4DPH > SAT 25.05.03 04:21l 67 Lines 2009 Bytes #999 (0) @ AMSAT
BID : ANS-145.03
Read: GUEST
Subj: ESA's Cluster Solves an Auroral Puzzle
Path: DB0ZKA<DB0FSG<I4UKI<IK5CKL<IK1ZNW<ON0AR<WB0TAX<W4DPH
Sent: 030525/0212Z @:W4DPH.#TPA.FL.USA.NOAM #:58478 [CLW] FBB $:ANS-145.03
From: W4DPH@W4DPH.#TPA.FL.USA.NOAM
To : SAT@AMSAT
AMSAT News Service Bulletin 145.03 From AMSAT HQ
SILVER SPRING, MD. May 25, 2003
To All RADIO AMATEURS
BID: $ANS-145.03
ESA's four Cluster spacecraft have made a remarkable set
of
observations that has led to a breakthrough in
understanding the origin
of a peculiar and puzzling type of aurora.
These aurorae - seen as bright spots in Earth's atmosphere
and called
'dayside proton auroral spots' - occur when fractures
appear in the
Earth's magnetic field, allowing particles given out from
the Sun to
squirt through and collide with the molecules in our
atmosphere. This
is the first time that a precise and direct connection
between the two
events has been made.
On 18 March last year, a jet of energetic solar protons
collided with
the Earth's atmosphere and created a bright 'spot' seen by
NASA's IMAGE
spacecraft, just as Cluster passed overhead and straight
through the
region where the proton jet was emanating. An extensive
analysis of the
Cluster results has now shown that the region was
experiencing a
turbulent event known as 'magnetic reconnection'. Such a
phenomenon
takes place when the Earth's usually impenetrable magnetic
field
fractures and has to find a new stable configuration.
Until the field
mends itself, solar protons leak through the gap and jet
into Earth's
atmosphere creating the dayside proton aurora.
ESA's Cluster Project Scientist, comments, "Thanks to
Cluster's observations scientists can directly and firmly
link for
the first time a dayside proton auroral spot and a
magnetic
reconnection event."
ESA's Cluster is a collection of four spacecraft, launched
on two Russian rockets during the summer of 2000. They are
now flying in formation around the Earth, relaying the
most detailed ever information about how the solar wind
affects our planet in 3D. The Cluster mission is expected
to continue until at least 2005.
[ANS thanks the European Space Agency for the above
information.]
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