Wednesday, December 21, 2011


More from Kepler: First Earth-Ish Sized Planets Discovered

Exoplanets are in the news recently, often being massively over-hyped in the popular press as 'new earth-like planets' that could harbour life. However:

According to The Telegraph: 'Astronomers have found a pair of Earth-sized planets orbiting a star similar to the Sun, though neither are believed to be suitable for life... Kepler-22b has the right temperature, but it is too big. (The planets) we're announcing today are just the right size, but too hot," astronomer David Charbonneau with Harvard University, told reporters...' (my italics) explains: 'The two Earth-size planets are among five alien worlds orbiting a star called Kepler-20 that is of the same class (G-type) as our sun, and is slightly cooler. Two of the star system's planets, Kepler-20e and Kepler-20f, are 0.87 times and 1.03 times the width of Earth, respectively, making them the smallest exoplanets yet known. They also appear to be rocky, and have masses less than 1.7 and 3 times Earth's mass, respectively. Scientists think that they are composed mainly of silicates and iron, much like the Earth, [so far so good, several habitability criteria are probably met by these planets] though they lack our planet's atmsophere [whoops]. Kepler-20e makes a circle around its star once every 6.1 days at a distance of 4.7 million miles (7.6 million kilometers) — almost 20 times closer than Earth, which orbits the sun at around 93 million miles (150 million km). The planet's sibling, Kepler-20f, makes a full orbit every 19.6 days, at a distance of 10.3 million miles (16.6 million km). Both planets circle closer to their star than Mercury does to the sun. These snuggly orbits around their star give the newfound planets steamy temperatures of about 1,400 degrees Fahrenheit (760 degrees Celsius) and 800 degrees Fahrenheit (430 degrees Celsius) — way too warm to support liquid water, and probably life, researchers said [double whoops]. Fressin said the chance of life on either of these planets is "negligible," though the researchers can't exclude the possibility that they used to be habitable in the past, when they might have been farther from their star. There is also a slim chance that there are habitable regions on the planets in spots between their day and night sides (the planets orbit with one half constantly facing their star and the other half always in dark). But astronomers aren't holding out hope. "The chances of liquid water and life as we know it on Kepler-20e and f are zero," Laughlin said.' (my italics)

Boston Globe Reports: 'A team led by Harvard astronomers announced yesterday a major milestone in the long-running hunt for worlds capable of supporting life elsewhere in the cosmos: the detection of a planet the size of Earth. The rocky planet, and another they found that is a bit smaller than Earth, are the smallest ever discovered orbiting another star. They provide the powerful proof astronomers have been waiting for that it is possible - using a space-based telescope - to detect planets that fit the profile that has successfully spawned life in our own solar system. Astronomers are still far from the ultimate dream of finding an inhabited world; these so-called exoplanets sit scorchingly close to their sun and would be too hot for life, at least as we know it. But just weeks ago, scientists reported the discovery of a planet that is bigger than Earth, but otherwise just right - sitting squarely in the “Goldilocks zone’’ that is not too hot and not too cold for liquid water. Together, the discoveries signal that that their search techniques are ready to pinpoint the right planets - if they are out there to be found.' (my italics)

These two planets, which are probably 2-3 times the mass of Earth respectively (cf. are tidally locked (i.e they always keep one face towards their sun). Moreover, this solar system has rocky planets and gas planets interspersed with each other, unlike our own solar system which has gas giants on the outside providing a 'gravitationoal shield' that attracts dangerous space debris: 'In our solar system, small, rocky worlds orbit close to the sun and large, gaseous worlds orbit farther out. In comparison, the planets of Kepler-20 are organized in alternating size: large, small, large, small and large.' -

The BBC notes: 'Both planets are now thought to be too hot to be capable of supporting life. But according to Dr Fressin, the planets were once further from their star and cool enough for liquid water to exist on their surface, which is a necessary condition for life.' (my italics)

But a necessary condition is not a sufficient condition; and even that is dependent upon whether or not there is H2O there, what atmosphere it once had, whether or not it has a magnetic field to shield itself from solar rays, etc. As Discovery News reports: 'The first two Earth-like worlds orbiting another star have been detected, although neither are believed to be suitable for life. But if the planets had water in the past, there's a good chance they could have hung on to it long enough for life to take hold, Linda Elkins-Tanton, with the Carnegie Institution in Washington DC, told reporters on a conference call Tuesday.' (my italics) Those 'if's', guestimated 'chances' and 'could's' are important conditional statements!

Recommended Resources

On the question of the sufficient conditions for the origin of life on a planet capable of sustaining its existence cf:

Stephen C. Meyer, Signature in the Cell: DNA and the Evidence for Intelligent Design (Harper One, 2010) - cf. Stephen C. Meyer's website

David Klinghoffer (ed.), Signature of a Controversy: Response to Critics of Signature in the Cell (Discovery Institute, 2011)

Stuart W. Pullen, Intelligent Design or Evolution: Why the Origin of Life and the Evolution of Molecular Knowledge Imply Design (ID Books, 2005)

Fazale Rana & Hugh Ross, Origins of Life (NavPress, 2004)

Paul Davies, The Origin of Life (Penguin, 2006)

Dean L. Overman, A Case against Accident and Self-Organization (Rowman & Littlefield, 2001)

Charles Thaxton et al, The Mystery of Life's Origins: Reassessing Current Theories (Ashgate, 1987) - on-line here

On the criteria for a planet able to sustain life cf:

Guillermo Gonzalez & Jay Richards, The Privileged Planet: How Our Place in the Cosmos Is Designed for Discovery (Regnery, 2004)

Peter D. Ward & Donald Brownlee, Rare Earth: Why Complex Life is Uncommon in the Universe (Springer, 2004)

Here's some podcasts from Old Earth Creationist organization Reasons to Believe on SETI and the Kepler discoveries:

'Will SETI Find Alien Life?' Play Episode Download Episode

'Another Super-Earth in the habitable zone?' Play Episode Download Episode

'Habitable Zone Planet Discovered' Play Episode Download Episode

'Scientists Discover Two Earth-Sized Planets Orbiting a Distant Star' Play Episode Download Episode


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