SO CLOSE, and yet so far. We are now pretty certain that there are billions of Earth-like planets in our galaxy – rocky worlds about the same size as ours, orbiting similar stars at similar distances. Ideal places to search for alien life. The nearest may be a mere 12 light years away, too far to visit but certainly close enough to take a look (see “Fake planets reveal distance to Earth’s nearest twin“).

Unfortunately, we can’t look – at least not yet. The discovery is extracted from data collected by the Kepler Space Telescope, which malfunctioned in May. There may be more surprises buried in Kepler’s data, but its Earthlike-planet-spotting days are over.

Still, the finding bolsters the belief that we are just a few years away from a truly jaw-dropping discovery. Kepler’s successor, the Transiting Exoplanet Survey Satellite, is due to launch in 2017. It will scour the sky for small rocky worlds around nearby stars, and is expected to find hundreds. Future instruments such as the James Webb Space Telescope and the proposed StarShade mission will follow up these discoveries, probing the planets’ atmospheres for signs of life.

The idea that there might be another living planet a few light years from home, orbiting a star visible with the naked eye, is a tantalising prospect. For better or worse, the odds are stacked against that. But we can be pretty confident that, if life is common in the universe, we will have found signs of it by the middle of the next decade.

This article appeared in print under the headline “We’re closer than ever to spotting ET”