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Tilt-A-World: Another Constraint on Habitability
January 12, 2012
Did you ever ride a Tilt-A-Whirl, one of those cheap carnival rides that makes you dizzy and sick? Our planet would be like that if its inclination were out of control. Without tilt stability, a new study reveals, we wouldn't be sick, we'd be dead, or never alive in the first place. It's not enough to be in the Habitable Zone. Would-be inhabited planets need to avoid a new problem, called “tilt erosion.”
A Young Moon for Life
January 3, 2012
Our moon is unique in the solar system. Just the right size and just the right distance, it is positioned to stabilize the tilt of Earth’s axis, providing stable seasonal cycles. Science lacks data so far to know just how unique the Earth-moon relationship in a habitable zone is among other stellar systems. We know from the planets of our own solar system that moons come in all sizes, from tiny Deimos to massive Titan, and orbit in apparently arbitrary radii from their host planets. What astrophysicists can do is predict what would happen on earth if things were different. That’s what one scientist did. Another discovery could change the view of the moon’s surface being unaltered for billions of years.
Observations Upset Models of Stellar Evolution
December 22, 2011
Stellar evolution models go back decades. Ever since the Hertzsprung-Russell diagram came out in 1910 (graphing temperature against luminosity), showing most stars fell on a line called the “main sequence”, astrophysicists have sought to understand the life cycle of stars from birth to death. In general, the story goes, collapsing clouds of gas and dust produce main-sequence stars that burn nuclear fuel till they run out. Depending on their masses, they end up as supernovae, red giants or slowly-cooling cinders. While red dwarfs cool down slowly into the darkness, supernovae and red giants eject mass outward into space . Two new planets found close to a red giant are among new headaches for theorists.
Earth’s Twin: What Does “Potentially Habitable” Mean?
December 5, 2011
The Kepler spacecraft has found dozens of “potentially habitable” planets around other stars, but this week announced one that some news sources are calling “Earth’s twin.”
It’s Still a Rare Earth
September 25, 2011
Now that hundreds of extrasolar planets are known, how do they compare to ours? The Kepler spacecraft has found a varied assortment of all sizes and distances away from their parent stars. Only a few reside in their star’s habitable zones. But that’s only the first of many requirements for life. Two recent studies indicate that Earth remains a rare bird in the celestial aviary.
Science Without an Object: Astrobiology, Alien Science
September 6, 2011
Can science exist without an observable object? In recent years we have seen serious scientists ponder alternate universes and parallel universes, dark matter, dark energy and other imponderable entities. String theory has yet to rest on observable data, and physicists at CERN are getting worried about not finding the hypothetical Higgs boson. Sooner or later, these theories need to detect their subjects or lose credibility in the science club. Perhaps nowhere else has the disconnect between hype and observation reached the absurd limits of astrobiology and alien science.