Bother

[james_davis_nicoll]

One of the most important characteristics of an alien planet is whether or not it falls into what's called the habitable zone ­— a Goldilocks-like range of not-too-close, not-too-far distances from the parent star that might allow the planet to host life.

Now scientists have redefined the boundaries of the habitable zone for alien planets, potentially kicking out some exoplanaets that were thought to fall within it, and maybe allowing a few that had been excluded to squeeze in.

Which is all well and good. What caught my eye was this:

The new definition isn't radically different from the old one. For example, in our own solar system, the boundaries of the habitable zone have shifted from between 0.95 astronomical units (AU, or the distance between Earth and the sun) and 1.67 AU, to the new range of 0.99 AU to 1.7 AU.

"It's a surprise that Earth is so close to the inner edge of the habitable zone," said astronomer Abel Méndez of the University of Puerto Rico at Arecibo, who was not part of the team behind the redefinition.

Even the inner edge being .95 AU is too close to comfort. .99 suggests the margin between us and uninhabitibility is far too narrow for comfort.

Comments

[elf]

I was particularly caught by this part:

He mentioned one planet in particular, Gliese 581d, was thought to lie at the outer edge of its star's habitable zone. With the new definition, though, it falls almost smack in the middle, making it perhaps a better candidate for extraterrestrial life.

"That will be a big change for that particular planet," Méndez said. "That means the prospects for life on the planet will be much better."

Um, someone has forgotten the problem with Schrodinger's methodology: The cat knows.

Gliese 581d has no better or worse "prospects for life" than it did ten years ago. We may be closer to identifying whether or not it contains life we'd recognize, but the planet's conditions haven't changed because our astrophysicists have adjusted their numbers.