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Two new extrasolar planets less massive than Saturn Mar 29, 2000
Origin of life in volcanic gases? Mar 27, 2000
Rogue worlds in Orion Mar 22, 2000
Interstellar helium found inside buckyballs Mar 21, 2000
Lunar clues to recent intense bombardment Mar 10, 2000
Evidence of underground water channels on Mars Mar 10, 2000

extrasolar planet
Two new extrasolar planets less massive than Jupiter
(Mar. 29, 2000)

Planet-hunters extraordinaire Geoff Marcy, Paul Butler, and Steve Vogt have formally announced their discovery of two extrasolar worlds less massive than Saturn. They orbit the stars HD 46375 and 79 Ceti, 109 and 117 light years away, respectively. Both planets are in tight orbits around their host stars with periods of 3 and 75 days. This is a landmark breakthrough, bringing the day closer when detection methods will be sensitive enough to detect Earth-mass extrasolar planets.

For more on extrasolar planets in general go here.

Origin of life in volcanic gases?
(Mar. 27, 2000)

A new theory by geologists at Washington University in St. Louis suggests that life may have arisen on the Earth and elsewhere from volcanic gases. Everett Shock, professor of earth and planetary sciences, and Mikhail Y. Zolotov, senior research scientist, describe a scenario where hot gases spewing from the Earth cool down sufficiently to allow basic hydrocarbons to form from the hydrogen and carbon monoxide present in the volcanic gases. A naturally occurring catalytic reaction, they claim, similar to an industrial process called Fischer-Tropsch synthesis, involving the iron compound magnetite as catalyst, is a crucial part of the process. If hydrocarbon synthesis takes place under such conditions, then so too may that of amino acids and complex organic polymers, leading, conceivably to self-replicating RNA molecules and the beginning of life.

More on this here.

Rogue worlds in Orion
(Mar. 22, 2000)

A British infrared survey of the Trapezium cluster, a star-forming region in the Orion Nebula, has produced evidence of 13 large rogue planets – worlds not in orbit around stars. The smallest is about 8 times more massive than Jupiter. The observations, carried out with the UKIRT in Hawaii, also disclosed more than a 100 brown dwarfs. Results are to be published in the Monthly Notices of the Royal Astronomical Society. For more go here.

Interstellar helium found inside buckyballs
(Mar. 21, 2000)

Researchers Luann Becker, of the University of Hawaii, Robert Poreda, of the University of Rochester, NY; and Ted Bunch of NASA Ames, have announced their finding of extraterrestrial helium trapped inside cage-like molecules of carbon atoms, known as fullerenes, that came from a layer of clay marking the Cretaceous-Tertiary Boundary. The interstellar origin of the helium is revealed by its enrichment in the isotope helium-3. Becker and Bunch had previously uncovered extraterrestrial fullerenes in samples from the 4.6-billion-year-old Allende meteorite and also Australia's Murchison meteorite.

Lunar clues to recent intense bombardment
(Mar. 10, 2000)

A sudden jump in the frequency of impact cratering on the Moon – and by inference, also on the Earth – about 400 million years may have played a central role in the recent evolution of terrestrial life. This suggestion emerges from a report by researchers at the Lawrence Berkeley National Laboratory, University of California at Berkeley, and the Berkeley Chronology Center which appears in the March 10 issue of Science. The new data show that the surge in cratering took place at the time of the "Cambrian explosion," a period in which the number and diversity of species on Earth rose dramatically. Explains Richard Muller, one of the authors of the paper: "Although most people assume that impacts cause death and destruction, it is possible that the additional stress of the impacts forced life to become more diverse and flexible. Just as we stress trees, through pruning, to make them give more fruit, the stress cause by catastrophic impacts may have forced evolution into new directions." The discovery of the recent cratering stemmed from an examination of a sample of lunar soil and, in particular of 155 tiny spherules it contained. Spherules are microscopic glass beads formed when droplets of molten basalt splashed out of a crater by the heat and force of an impact subsequently cooled and hardened. The Berkeley team dated their spherules using an ultrasensitive technique based on the ratios between two argon isotopes. From the ratio of argon-40 to argon-39 as measured by neutron irradiation followed by laser-driven mass spectroscopy, the age of the spherules could be determined. Ranging in size from less than 100 microns to more than 250 microns, the spherules came from a sample collected in 1971 by the Apollo-14 near Mare Imbrium (Sea of Rains), the dark crater that dominates the moon's face. Statistical and chemical analyses showed that the spherules studied came from approximately 146 different craters. "Even though we don't know which crater was the source of each spherule, the distribution of the ages of the spherules from a single lunar site should reflect the age distribution of craters on the Moon," said Muller. The results of the study have implications not only for the evolutionary history of life on Earth but also for our understanding of the Solar System. One problem is to come up with a mechanism that could explain the increase in impacts, particularly one that lasted 400 million years. Muller believes it offers further evidence that the Sun has a companion star – "Nemesis", a name coined by Muller in 1984 when the theory was first aired. "The increase in impacts could be due to a sudden change in the orbit of Nemesis," Muller says. "If a passing star perturbed Nemesis into a more eccentric orbit, that would account for the increase in impacts."

Reference: Lunar Impact History from 40Arg/39Arg Dating of Glass Spherules. Richard Muller, Paul Renne, and Timothy Culler. Science Mar 10 2000.

Evidence of underground water channels on Mars
(Mar. 10, 2000)

New observations of Mars by Mars Global Surveyor (MGS) reveal that the planet's flat northern lowlands could have been a region where water rapidly accumulated billions of years ago. Elevation and gravimetric data collected by MGS indicate that the planet went through a period of fast cooling in its youth. The measurements also provide evidence for immense, underground channels that could have carried large volumes of water. According to MIT's Maria Zuber, co-author of a paper just published in the journal Science: "The crustal thickness map shows that, as for Earth, Mars has two distinct crustal provinces". Below the rough southern highlands, the crust, estimated at 80 km (50 miles) thick, gets progressively thinner from the south pole to the north. By contrast, the northern lowlands have a crust of uniform thickness, about 35 km (22 miles) deep. The crustal structure accounts for the elevation of the Martian northern lowlands, which in turn controlled the northward flow of water early in the planet's history. This would have produced a network of valleys and outflow channels. The features are about 201 km (125 miles) wide and over 1,600 km (1,000 miles) long, with features that can be explained in terms of water flow on the surface or in a submarine environment later buried by sediments. The large size of these channels implies that any bodies of water in the northern lowlands could have built up rapidly. The now buried channels may represent the means for filling an early ocean. The gravity and topography also provide information about the cooling of Mars over time. The period of rapid interior heat loss may correspond to the era when Mars had a warmer climate, liquid water flowed on the surface, and the planet's surface was shielded from the solar wind by a global magnetic field – conditions more clement to the appearance of life. (Photo credit: NASA)

Reference: Internal Structure and Early Thermal Evolution of Mars from Mars Global Surveyor Topography and Gravity. Maria T. Zuber, Sean C. Solomon, Roger J. Phillips, David E. Smith, G. Leonard Tyler, Oded Aharonson, Georges Balmino, W. Bruce Banerdt, James W. Head, Catherine L. Johnson, Frank G. Lemoine, Patrick J. McGovern, Gregory A. Neumann, David D. Rowlands, and Shijie Zhong. Science Mar 10 2000: 1788-1793.


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