  The Faint Young Sun Paradox comes from the fact that solar luminosity
(2-4)x10^9 years ago was insufficient to support the Earth's temperature
necessary for the efficient development of geological and biological evolution
(particularly, for the existence of considerable volumes of liquid water). It
remains unclear by now if the so-called greenhouse effect on the Earth can
resolve this problem. An interesting alternative explanation was put forward
recently by M.Krizek (New Ast. 2012, 17, 1), who suggested that planetary
orbits expand with time due to the local Hubble effect, caused by the
uniformly-distributed Dark Energy. Then, under a reasonable value of the local
Hubble constant, it is easy to explain why the Earth was receiving an
approximately constant amount of solar irradiation for a long period in the
past and will continue to do so for a quite long time in future.
