If we ask the question about the possible existence of the life outside the Earth, we first have to determine the habitable zone (HZ) for our solar system. The HZ of distances between a main sequence star and an Earth-like planet is roughly defined as the range of mean orbital radii which imply moderate planetary surface temperatures suitable for the development and subsistence of carbon-based life. The latter precondition is usually taken as the requirement that liquid water is permanently available at the planet’s surface. The HZ concept was introduced by Huang [1, 2] and extended by Dole [3] and Shklovskii and Sagan [4].