[meteorite-list] Meteorites Used To Study Solar Activity

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Sep 26 17:14:55 2006
Message-ID: <200609262114.OAA12617_at_zagami.jpl.nasa.gov>

http://www.upi.com/NewsTrack/view.php?StoryID=20060926-015940-3936r

Meteorites used to study solar activity
UPI
September 26, 2006

OULU, Finland (UPI) -- A Finnish-led international team has
used meteorites to investigate the sun's solar activity of past centuries.

Ilya Usoskin at Finland's Sodankyla Geophysical Observatory and
colleagues compared the amount of Titanium 44 in 19 meteorites that have
fallen to the Earth the past 240 years. They said their findings confirm
that solar activity increased strongly during the 20th century. They
also find the sun has been particularly active during the past few decades.

The scientists say studying the sun's activity is one of the oldest
astrophysical projects, as astronomers began recording the number of
sunspots to trace the sun's magnetic activity 400 years ago.

The team examined a set of 19 meteorites whose dates of fall are
precisely known, measuring the amount of radioactive isotope Titanium 44
in each meteorite. Titanium 44 is produced by the cosmic rays in the
meteorites while they are outside the Earth's atmosphere. After the
meteorite has fallen, it stops producing the isotope.

By measuring the Titanium 44 in the meteorites, the scientists
determined the level of solar activity at the time the meteorite fell.

The study appears in the journal Astronomy & Astrophysics Letters.
Received on Tue 26 Sep 2006 05:14:50 PM PDT