August 2006

Where Have All the Shadows Gone?

August 31, 2006

Cosmological shadows? Theory predicts that objects between us and the source of the cosmic microwave background should cast them. Specifically, the hot gases found in clusters of galaxies should show a measurable shadow effect produced by that background radiation, and there are reports of such effects from various observers. The scattering of the cosmic microwave […]

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Quasars, Black Holes and a Reionized Universe

August 30, 2006

A black hole two billion times more massive than the Sun is not something you find every day. Even more unusual is to find it embedded in a quasar that is 12.7 billion light years from Earth. But that’s just what Tomotsugu Goto (Japan Aerospace Exploration Agency) seems to have found using the Subaru optical-infrared […]

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Early Notes Toward a Galactic Census

August 29, 2006

What sort of stars harbor the planetary systems we’ve thus far identified? The answer is easy: most of the known exoplanets were found through radial velocity surveys, and these focus on nearby Sun-like stars. Thus we’re looking at a range of stars between late-F and early-K class dwarfs, and almost all are within 50 parsecs […]

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Gravity, Inertia, Exotica

August 28, 2006

Are we ever going to understand what makes matter resist acceleration? If we can get a handle on inertia, we’ll have a better idea what’s possible when it comes to exotic propulsion. 19th Century physicist Ernst Mach believed that inertia was the result of matter being acted upon by all other objects in the universe, […]

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Weekend Vista: Into the Magellanics

August 26, 2006

Now and then it’s good to step back from interstellar advocacy, especially on a weekend, and just look at the sky. To that end, the photograph below can be considered an object of contemplation, something to quiet the rush of the work week and return the mind to the far reaches. You’re looking at a […]

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A Fourth Planet for Mu Arae

August 25, 2006

Hunting for exoplanets isn’t a matter of peering into telescopes and seeing faint specks of light. It’s all about combing through data — reams and reams of data thankfully digitized — for the telltale signatures of planets. And it’s fascinating to reflect that in many cases the signatures we seek are in our possession in […]

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Eight Planets It Is

August 24, 2006

So now we know what a planet is. As confirmed by the passage of a revised resolution at the International Astronomical Union’s general assembly today in Prague, a planet meets the following criteria: It must be in orbit around a star It must possess sufficient mass to allow it to assume a round shape; i.e., […]

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The Latest on the Tau Zero Foundation

August 23, 2006

by Marc Millis Centauri Dreams is pleased to report again on the status of the Tau Zero Foundation. Founded by Marc Millis, former head of NASA’s Breakthrough Propulsion Physics program, the Foundation’s goal is to support credible research into interstellar flight, with a realistic understanding that incremental progress toward this goal can only be made […]

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New Evidence for Dark Matter

August 22, 2006

Gravitational lensing, discussed here recently as the motive for the FOCAL mission to the Sun’s gravity lens, is suddenly back in the news. This time it’s being used to make measurements of dark matter of a startlingly precise kind, measurements that in some quarters are being hailed as the first solid evidence that dark matter […]

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Galileo Weighs in On Planetary Definitions

August 21, 2006

Centauri Dreams continues to admire the clarity of the draft IAU resolution on the definition of a planet. Although the criteria are easily understood, they also present teaching opportunities (imagine all those schoolchildren learning what a barycenter is, and why Pluto/Charon make a double planet thanks to the location of their center of gravity!). This […]

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