New data challenge Earth atmosphere theory

U.S. geochemists challenged commonly held theories about how gases are expelled from the Earth and how a planet's atmosphere is formed.

Rensselaer Polytechnic Institute researchers said their new theory could change the way scientists view the timing and mechanism involved in the formation of Earth's atmosphere, as well as the atmospheres of Mars and Venus.

The team, led by Professor E. Bruce Watson, said it has found substantial evidence that argon atoms are strongly bound in the minerals of Earth's mantle and move through those minerals at a much slower rate than previously thought. In fact, they said they discovered even volcanic activity is unlikely to dislodge argon atoms from their resting places within the mantle.

Watson said that finding conflicts with widely held theories on how gases moved through early Earth to form our atmosphere and oceans.

The study that included Professor Daniele Cherniak and postdoctoral researcher Jay Thomas is described in the journal Nature.

Jupiter's Composition Throws Planet-formation Theories into Disarray
by Robert Roy Britt
Nov 17 1999
Examining four-year-old data, researchers have found significantly elevated levels of argon, krypton and xenon in Jupiter's atmosphere that may force a rethinking of theories about how the planet, and possibly the entire solar system, formed. Prevailing theories of planetary formation hold that the sun gathered itself together in the center of a pancake-shaped disk of gas and dust, then the planets begin to take shape by cleaning up the leftovers. In Jupiter's current orbit, 5 astronomical units from the sun, temperatures are too warm for the planetesimals to have trapped the noble gases. Only in the Kuiper belt -- a frigid region of the solar system more than 40 AU from the sun -- could planetesimals have trapped argon, krypton and xenon.

While lead researcher Tobias Owen does not put much stock in the idea that Jupiter might have migrated inward to its present position, other scientists on the team say the idea merits consideration. Owen expects the probes will find similarly high levels of noble gases in Saturn, Uranus and Neptune. Hints of these gases have even been found in the thick atmosphere of Venus, another planet now begging more study.
Jupiter gave birth to Uranus and Neptune
by Dr David Whitehouse
8 December, 1999
Not too long ago, scientists regarded the orbits that the planets circle our Sun as being the ones they were born in. Now they are realising that this is not the case. Uranus and Neptune may have migrated outwards and Jupiter may have come in from the outer cold. Scientists have always been slightly puzzled by the positions of Uranus and Neptune because in their present locations it would have taken longer than the age of the Solar System for them to form. Scientists from Queen's University suggest that the four giant planets started out as rocky cores in the Jupiter-Saturn region, and that the cores of Uranus and Neptune were tossed out by Jupiter's and Saturn's gravity.

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