Obviously we have seen evidence of “tidal heating” in some of the satellites of Jupiter and Saturn. So if there are any “Super-Earths” that are orbiting outside of a star’s “Goldilocks zone” then they still might be worth checking out.

This article misses the fact that our planet-finding capabilities are currently weighted towards finding very large planets in very close orbit around very small stars. Using these current techniques, we would not be able to find Earth from Alpha Centauri.

So, we cannot assume that there are NO Earth-sized planets there.


Earth is the only known example of an inhabited planet in the Universe, so the search for alien life has focused on Earth-like worlds. But what if there are alien worlds that are even more habitable than Earth-like planets?

A recent paper in the journal Astrobiology examines the potential for so-called “superhabitable” worlds. One such planet might even exist around the stellar system closest to Earth: Alpha Centauri B.

The study was authored by René Heller of McMaster University in Ontario, Canada, and John Armstrong of Weber State University in Ogden, Utah, USA. According to the authors, their collaboration was “inspired by a question John Armstrong asked online during an AbGradCon talk in 2012.”

The Astrobiology Graduate Conference (AbGradCon) is supported by the NASA Astrobiology Institute, and is organized by graduate students and post docs in fields related to astrobiology. AbGradCon provides early career researchers with the chance to discuss research, network and collaborate. AbGradCon 2014 will be held at the Rensselaer Polytechnic Institute (RPI) in Troy, New York. For more information, visit: http://www.abgradcon.org/index.html

To be habitable, a world (planet or moon) does not need to be located in the stellar habitable zone (HZ), and worlds in the HZ are not necessarily habitable. Here, we illustrate how tidal heating can render terrestrial or icy worlds habitable beyond the stellar HZ. Scientists have developed a language that neglects the possible existence of worlds that offer more benign environments to life than Earth does. We call these objects “superhabitable” and discuss in which contexts this term could be used, that is to say, which worlds tend to be more habitable than Earth. In an appendix, we show why the principle of mediocracy cannot be used to logically explain why Earth should be a particularly habitable planet or why other inhabited worlds should be Earth-like.

Superhabitable worlds must be considered for future follow-up observations of signs of extraterrestrial life. Considering a range of physical effects, we conclude that they will tend to be slightly older and more massive than Earth and that their host stars will likely be K dwarfs. This makes Alpha Centauri B, which is a member of the closest stellar system to the Sun and is supposed to host an Earth-mass planet, an ideal target for searches for a superhabitable world. Key Words: Extrasolar terrestrial planets—Extraterrestrial life—Habitability—Planetary environments—Tides. Astrobiology 14, 50–66.


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