Home > M. Stars > Elsewhere in Outer Space…New Earth

Elsewhere in Outer Space…New Earth


The attention being paid to the rover Curiosity’s arrival on Mars is understandable, but what’s going on elsewhere in the cosmos? Here’s the latest word on the Kepler spacecraft (which is looking for earth-sized planets outside our solar system): Kepler has discovered 74 confirmed planets, of which two are earth-sized (though neither is in its star’s habitable zone). The total number of exoplanets discovered to date: 777.

Now here is where the numbers really get interesting. Analysis of exoplanet data has led to the following conclusions: the Milky Way contains 100 billion or so stars; each of these stars is estimated to have 1.6 planets. Crunching the numbers, this means that our galaxy is estimated to contain 160 billion solar-bound planets.

Let’s take this a bit further. Many conditions are necessary for the formation of life on a planet. One of the most important is that a planet orbit a star of the correct type, spectral class “G” to “mid-K.” Five to ten percent of stars fall into this range; applying this filter leaves us with 8-16 billion candidate planets.

And here’s another consideration: the planet must fall within a star’s habitable zone. The Kepler team estimates that at least half a billion planets meet this criterion.

There are other requirements candidates have to meet: their star must have a high metallicity, low variation, and a stable habitable zone. The planet must also have a high mass, an orbital inclination not too far off the ecliptic, and geochemistry capable of producing amino acids, the building blocks of life. Did I mention surface water (lots of it)?

OK, it’s a lot. But how many New Earths do we really need? A hundred? A thousand? Heck, the discovery of just one would send shivers down our backs, especially if the particular planet features copious oxygen in its atmosphere. And I won’t even speculate what the response would be if we found chlorophyll in its chemical signature.


And after all, there is the question of how to get there. That’s why the photograph above was taken by the Huygens probe, which landed on Saturn’s moon Titan. We can get there.


Photo: Composite Image Taken During Huygen’s Descent to the Surface. WikiCmns; NASA/JPL Public Domain with attribution.

  1. August 11, 2012 at 3:55 pm

    Imagine that!! I mean, really. Imagine it. Boggles, doesn’t it. There MUST be at least one out there!

  2. August 12, 2012 at 2:14 am

    sharon: i think we could find a pale blue dot in the next 5-10 years…keep yr fingers crossed! RT

  1. December 11, 2012 at 7:51 pm

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