that maybe there is not as much chance of finding life in our galaxy or universe as some would have us believe. We may be it." Brian Cox, physicist and popular science celebrity confesses his support for the hypothesis in his 2014 BBC production of the Human Universe. Criticism Cases against the Rare Earth hypothesis take various forms. The hypothesis appears anthropocentric The hypothesis concludes, more or less, that complex life is rare because it can evolve only on the surface of an Earth-like planet or on a suitable satellite of a planet. Some biologists, such as Jack Cohen, believe this assumption too restrictive and unimaginative; they see it as a form of circular reasoning. According to David Darling, the Rare Earth hypothesis is neither hypothesis nor prediction, but merely a description of how life arose on Earth. In his view, Ward and Brownlee have done nothing more than select the factors that best suit their case. Critics also argue that there is a link between the Rare Earth hypothesis and the unscientific idea of intelligent design. Exoplanets around main sequence stars are being discovered in large numbers An increasing number of extrasolar planet discoveries are being made, with planets in planetary systems known as of . Rare Earth proponents argue life cannot arise outside Sun-like systems, due to tidal locking and ionizing radiation outside the F7–K1 range. However, some exobiologists have suggested that stars outside this range may give rise to life under the right circumstances; this possibility is a central point of contention to the theory because these late-K and M category stars make up about 82% of all hydrogen-burning stars. Current technology limits the testing of important Rare Earth criteria: surface water, tectonic plates, a large moon and biosignatures are currently undetectable. Though planets the size of Earth are difficult to detect and classify, scientists now think that rocky planets are common around Sun-like stars. The Earth Similarity Index (ESI) of mass, radius and temperature provides a means of measurement, but falls short of the full Rare Earth criteria. Rocky planets orbiting within habitable zones may not be rare Some argue that Rare Earth's estimates of rocky planets in habitable zones ( in the Rare Earth equation) are too restrictive. James Kasting cites the Titius-Bode law to contend that it is a misnomer to describe habitable zones as narrow when there is a 50% chance of at