What, More Earth-Like Exoplanets? - Evolution News & Views

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What, More Earth-Like Exoplanets?

Like a broken copier, popular science media just keeps spitting this stuff out. Now it's Wired reporting on the latest guesstimate of how many Earth-like exoplanets there probably maybe almost certainly must be in our galaxy alone. The number now stands at 10 billion, though Wired also notes another hopeful figure even larger, at 100 billion.

Funny, it seems like only six months ago we were noting an earlier celebratory estimate of just 1 million such planets. Let's see here, yes it was just six months ago. From 1 million to 10 or 100 billion -- man, they're really churning them out.

Wired has the exciting information:

About 40 percent of red dwarf stars may have Earth-sized planets orbiting them that have the right conditions for life.

Red dwarfs -- which are smaller and cooler than our sun -- are extremely common, making up 80 percent of stars in the galaxy. Their ubiquity suggests that there are tens of billions of possible places to look for life beyond Earth, with at least 100 such planets located nearby.

The new estimate comes from a team of astronomers using the European Southern Observatory's HARPS planet-hunting telescope to look at a sample of 102 nearby red dwarfs over a six-year period. The telescope checked for a characteristic wobble from the star, indicating that at least one planet was tugging on it while orbiting around.

The search found nine planets with between one and 10 Earth masses, including two in the habitable zone, possibly giving them the right temperature to have liquid water. Because red dwarfs don't produce as much heat as our sun, their habitable zones occur much closer to the star.

OK, this is all about red dwarfs. One of the central features of Earth is that it goes around a yellow dwarf star, so, almost by definition, planets around red dwarfs are going to be significantly less Earth-like than, say, Mars and Venus.

Yet somewhere out there, there have got to be nearly countless planets with life, even intelligent life, otherwise the gifts of our own planet, swelling with complex and intelligent life, seems rather special and somehow a privilege. Which can't be! It is inconvenient that all the ETs have so far kept any evidence of their existence quiet from us. The silence is deafening.

Go back and read Discovery fellow and astronomer Guillermo Gonzalez on why some current thinking -- or anyway, blogging and journalism -- about the abundance of livable planets is, in all likelihood, wildly overblown.