Outer Limits Not Lively

One of the “cosmic coincidences” cited in the intelligent-design treatise The Privileged Planet1 is the “galactic habitable zone” – a fairly narrow region of the galaxy where planets can form and exist safely.  The outer regions of the galaxy were described as lacking the heavy elements necessary for planet formation.     Score one for […]

Mars Red-Faced Without Water

The Martians are singing How dry I am.  Scientists have a new explanation for how Mars turned red without water: it’s just dry dust tumbling in the wind.  This new hypothesis was announced by Live Science, Science Daily, New Scientist, and, based on a presentation at the European Planetary Science Congress last week.1    […]

Earth Size Gives Life Edge

The earth seems to be holding onto its status as a privileged planet.  New Scientist reported that a rocky planet’s size is linked to its ability to sustain a magnetic field and plate tectonics.  This means that some of the “super-earths” found around other stars (5-10 times the size of earth) may not be habitable.  […]

Milking the Martian Meteorite

One would think everything has been told about ALH 84001, the Martian meteorite that made a splash in 1996 with claims it contained fossils of living organisms.  That claim was essentially discarded in subsequent years.  Its major contribution was giving life to a new science called astrobiology and energizing NASA’s Mars program.  Now, a new […]

What’s Up With the Planets?

Here are planets and moons making news in our celestial neighborhood, the solar system.  Maybe we’ll drop in on another neighborhood while we’re looking around. Venus resurfacing:  Planetary geologists can’t get away from the evidence that Venus underwent a planet-wide volcanic resurfacing epoch.  Crater counts and lava flow surveys leave little room for doubt that, […]

Planet-Makers Ask Miracles to Evade Death Spiral

Remember the old artwork of planets gently forming out of dust orbiting a young star?  That’s all gone.  Reality has set it.  Clumps of material a meter across need help – almost miraculous help – to avoid getting sucked into the star in a giant death spiral.  If you don’t believe it, ask John Chambers […]

Faint Young Sun Paradox Resolved

For decades, astronomers and geologists have worried about a paradox.  Stellar evolution theory claims sunlight on the early earth would have been 20-30% dimmer than it is today, but geology shows the oceans were liquid in the earliest (Archean) rocks.  For that matter, so does the book of Genesis, but that record is not usually […]

Comet-Ocean Theory Gets Another Splash

National Geographic News gave some halfway-enthusiastic press to another recurrence of a theory that circulates from time to time – that earth got its ocean water from comets.  They gave air time to work by Uffe Jorgensen and a team from the Niels Bohr Institute in Denmark that concludes “comets were the culprits” in the […]

Mars Looks More Hostile to Life

The methane Mars produces gets destroyed rapidly.  This is leading some planetary scientists to get depressed about the possibility of finding life there.     The BBC News, and New Scientist all reported on the paper in Nature,1 saying this represents bad news for life.  In models by Franck Lefevre and Francois Forget, patterns […]

Salting News with the L Word Life

Small amounts of sodium were detected in ice particles erupting from Saturn’s moon Enceladus.  Deduction: this might lower the melting point of underground ice, forming subsurface pockets of liquid water – perhaps an ocean.  Conclusion: Life!  It doesn’t matter that Enceladus has no other factors conducive to life than water, or that salt is generally […]

This Place Really Has Atmosphere

Of all the bodies in the solar system, only eight have a substantial atmosphere.  If you add in those with tenuous atmospheres, you can add in Triton and Mercury, and maybe a few others, till it becomes pedantic to call it an atmosphere if there are only a few short-lived molecules hovering over a moon.  […]

Planets Can’t Grow Past the Electric Fence

In the artwork, it looks so simple: dust clumps into planets that grow into nice, orbiting solar systems – like ours.  It’s not so simple when you try to nail down the real physics.  Planet-building models have to contend with a host of variables and barriers to growth (accretion).  Another barrier was discussed in Astrophysical […]

Milankovitch Cycles Indistinguishable from Randomness

A claim has often been made by geologists that the rock sediments record cyclical changes in Earth’s orbit.  Milankovitch cycles, named for the man who analyzed them, are a set of regular periodic changes to the orbital eccentricity, obliquity, and axial precession of the Earth over tens and hundreds of thousands of years.  These subtle […]

Building Planets: Can’t Make Them, But Hurry

Constructing planets is a delicate business.  Trying to get tiny bits of dust to join up into balls has never been found to work.  It has to work fast, though, because unless the whole planet clears its dust lane, it will be dragged into the star in short order.  It seems you can’t get there […]

State of the Moon Titan Addressed

Each May, a series of articles on major topics of geological interest, written by leading experts in the field, is published in the Annual Review of Earth and Planetary Sciences.  This year’s issue includes a treatise on Titan, the large moon of Saturn, written by the two titans of Titan science, Jonathan Lunine and Ralph […]
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