The Kepler space telescope, which has its eye on 150,000 stars, is beginning to home in on Earth-size planets.

Earth 2.0 would be a rocky planet the size of our own, orbiting a star like the sun at a distance where the surface temperatures would allow liquid water oceans, assuming the planet was sheathed in an atmosphere containing greenhouse gases.

We could look for life on Earth 2.0 via “technosignatures” such as radio signals produced by intelligent life.

Despite being denied public funds and derided by some politicians for seeking “little green men”, SETI still carries out searches with private money.