Scientists
think Saturn’s dazzling rings are older than believed
LOS
ANGELES (AP) -- Saturn’s shimmering rings may be as old as the solar system,
scientists said Wednesday, debunking earlier theories that the rings were formed
during the dinosaur age.
Astronomers
had thought Saturn’s rings were cosmically young, likely born some 100 million
years ago from leftovers of a meteoric collision with a moon, based on data by
NASA’s Voyager spacecraft in the 1970s.
However,
new data from the orbiting international Cassini spacecraft suggest the rings
have existed as far back as 4.5 billion years ago, roughly the same time the
sun and planets formed. The probe also found evidence that ring particles are
constantly shattering and regrouping to form new rings.
“Recycling
allows the rings to be as old as the solar system although continually
changing,” said Larry Esposito, a Cassini scientist from the University of
Colorado, Boulder.
The
findings were presented at an American Geophysical Union meeting in San
Francisco and will be published in a future issue of the astronomical journal Icarus.
Saturn’s
trademark arcs have awed astronomers since Galileo’s time. Scientists are
interested in the rings because they are a model of the disk of gas and dust
that initially enveloped the sun and studying them could yield clues about
planet formation.
Saturn’s
ring system consists of seven major rings and thousands of ringlets, mostly
made of orbiting ice mixed with dust and rock fragments.
The
notion that Saturn’s rings may be a permanent feature was based on observations
by the ultraviolet spectrograph instrument on Cassini, which viewed the light
reflected from the rings and watched stars passing behind them. The Cassini
mission, funded by NASA and the European and Italian space agencies, was
launched in 1997 and reached Saturn in 2004.
The
mission is managed by NASA’s Jet Propulsion Laboratory in Pasadena.