October 2007

Reconsidering Gliese 581

October 31, 2007

Gliese 581 continues to occupy the attention, and understandably so. At least three planets orbit this M-dwarf, one of which sprang into the public consciousness with the announcement that it might be in its star’s habitable zone. But both Gl 581c and d are interesting from the habitability standpoint, even if subsequent discussions have pointed [...]

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A Closer Look at Vesta

October 30, 2007

It seems extraordinary to speak of picking up pieces of an asteroid on the surface of the Earth, but the meteorites known as eucrites are confidently identified with Vesta, the brightest asteroid in the sky (and the only one visible with the naked eye). With the Dawn mission on its way to both Ceres and [...]

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Hot Jupiters Co-existing with Earth-like Worlds?

October 29, 2007

One of the surprises of the early planet-hunting era has been the discovery of ‘hot Jupiters,’ giant planets orbiting extremely close to their parent star. That these planets should be prolific in our catalog at present makes sense given the nature (and limitations) of radial velocity detection methods, but before we started finding them, there [...]

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Notes & Queries 10/27/07

October 27, 2007

More notes on the ‘wandering planet’ scenario advanced by John Debes (Carnegie Institution of Washington) and Steinn Sigurðsson (Penn State), which suggests that planets ejected from their stars as their solar systems formed could conceivably keep enough internal heat to maintain an atmosphere and sustain a liquid ocean under ice. Debes’ simulations show that a [...]

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A Gravitational Explanation for Dark Matter

October 26, 2007

Because dark matter has never been directly observed, we’re left trying to figure it out using deductions based on its presumed effects on visible matter. Seven dwarf satellite galaxies of the Milky Way — Carina, Draco, Fornax, Leo I, Leo II, Sculptor and Sextans — offer a case in point. Stars in these galaxies do [...]

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A Defect in the Cosmos?

October 25, 2007

A ‘defect’ in spacetime may be one of the most curious findings of the data collected from the Wilkinson Anisotropy Probe. What WMAP gave us is the earliest image of the cosmos we have in our repertoire, showing temperature changes across the microwave background thought to be the aftereffect of the Big Bang. When Marcos [...]

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PLATO: A New ESA Planet Hunter Concept

October 24, 2007

Looking through the list of candidate missions selected by the European Space Agency recently, my attention was immediately drawn to PLATO, a planet-finder spacecraft designed to study transiting exoplanets and to measure the seismic oscillations of the stars they orbit. Although at first reminiscent of COROT, PLATO (Planetary Transits and Oscillations of Stars) is really [...]

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Finding the Dino Killer

October 23, 2007

By Larry Klaes Tau Zero journalist Larry Klaes now returns with a look at the impact that evidently killed the dinosaurs, and the unusual family of planetoids now thought responsible. Is Chicxulub an event that could only have happened in the distant past, or a warning of possible danger ahead? About 65 million years ago, [...]

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Self-Consciousness Among the Stars

October 22, 2007

As a coda to our recent SETI discussion, two newspaper stories on the subject ran over the weekend. I follow how the media handle this subject because public interest in SETI seems to remain high, and the cultural expectations that show forth in these articles may give us a glimpse of what would happen in [...]

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Notes & Queries 10/20/07

October 20, 2007

South Dakota’s Homestake Gold Mine, famed for the work Ray Davis did on solar electron-neutrinos, may point toward clues in another search, the quest for dark matter. Experiments called LUX and DEAP/CLEAN are aimed at measuring the recoil of dark matter particles off ultra-pure, non-radioactive gases like purified argon and xenon. Robert McTaggart (South Dakota [...]

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