Andrew Yee
August 19th 05, 12:17 PM
Department of Public Affairs
University of Toronto
Toronto, Canada
Contact:
Professor Yuri Amelin, Geological Survey of Canada
(613) 995-3471
Aug 18/05
Discovery of 'young' material in meterorites defies linear theory of solar
system's origin
From order to disorder: A monkey wrench in solar system evolution?
By Sonnet L'Abbé
A U of T scientist has found unexpectedly 'young' material in meteorites
-- a discovery that breaks open current theory on the earliest events of
the solar system.
A paper published today in the August issue of Nature reports that the
youngest known chondrules -- the small grains of mineral that make up
certain meteorites -- have been identified in the meteorites known as
Gujba and Hammadah al Hamra.
Researchers who have studied chondrules generally agree that most were
formed as a sudden, repetitive heat, likely from a shock wave, condensed
the nebula of dust floating around the early Sun. Thinking that an
analysis of the chondrules in Gujba and Hammadah al Hamra would be
appropriate for accurately dating this process, U of T geologist Yuri
Amelin, together with lead author Alexander Krot of the University of
Hawaii, studied the chondrules' mineralogical structure and determined
their isotopic age. "It soon became clear that these particular chondrules
were not of a nebular origin," says Amelin. "And the ages were quite
different from what was expected. It was exciting."
Amelin explains that not only were these chondrules not formed by a shock
wave, but rather emerged much later than other chondrules. "They actually
post-date the oldest asteroids," he says. "We think these chondrules were
formed by a giant plume of vapour produced when two planetary embryos,
somewhere between moon-size and Mars-size, collided."
What does this mean in the grand scheme of things? The evolution of the
solar system has traditionally been seen as a linear process, through
which gases around the early sun gradually cooled to form small particles
that eventually clumped into asteroids and planets. Now there is evidence
of chondrules forming at two very distinct times, and evidence that embryo
planets already existed when chondrules were still forming. "It moves our
understanding from order to disorder," Amelin admits. "But I'm sure that
as new data is collected, a new order will emerge."
Financial support for this project was provided by NASA and the Canadian
Space Agency.
University of Toronto
Toronto, Canada
Contact:
Professor Yuri Amelin, Geological Survey of Canada
(613) 995-3471
Aug 18/05
Discovery of 'young' material in meterorites defies linear theory of solar
system's origin
From order to disorder: A monkey wrench in solar system evolution?
By Sonnet L'Abbé
A U of T scientist has found unexpectedly 'young' material in meteorites
-- a discovery that breaks open current theory on the earliest events of
the solar system.
A paper published today in the August issue of Nature reports that the
youngest known chondrules -- the small grains of mineral that make up
certain meteorites -- have been identified in the meteorites known as
Gujba and Hammadah al Hamra.
Researchers who have studied chondrules generally agree that most were
formed as a sudden, repetitive heat, likely from a shock wave, condensed
the nebula of dust floating around the early Sun. Thinking that an
analysis of the chondrules in Gujba and Hammadah al Hamra would be
appropriate for accurately dating this process, U of T geologist Yuri
Amelin, together with lead author Alexander Krot of the University of
Hawaii, studied the chondrules' mineralogical structure and determined
their isotopic age. "It soon became clear that these particular chondrules
were not of a nebular origin," says Amelin. "And the ages were quite
different from what was expected. It was exciting."
Amelin explains that not only were these chondrules not formed by a shock
wave, but rather emerged much later than other chondrules. "They actually
post-date the oldest asteroids," he says. "We think these chondrules were
formed by a giant plume of vapour produced when two planetary embryos,
somewhere between moon-size and Mars-size, collided."
What does this mean in the grand scheme of things? The evolution of the
solar system has traditionally been seen as a linear process, through
which gases around the early sun gradually cooled to form small particles
that eventually clumped into asteroids and planets. Now there is evidence
of chondrules forming at two very distinct times, and evidence that embryo
planets already existed when chondrules were still forming. "It moves our
understanding from order to disorder," Amelin admits. "But I'm sure that
as new data is collected, a new order will emerge."
Financial support for this project was provided by NASA and the Canadian
Space Agency.