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The starry sky is now far more fascinating to us than it ever was to our forebears. Stars may seem just points of light, but we’ve learnt recently that most are orbited by retinues of planets, just as our Sun is. Our galaxy probably harbours many billions of planets. The most fascinating question of all is how many might harbour life — even intelligent life? Could Kepler 438b be part of the answer?

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Kepler 438b is a very Earth-like planet whose discovery was announced this week. There’s special interest in “twins” of our Earth — planets the same size as ours, orbiting other Sun-like stars. Kepler 438b is one of those. It’s 475 light years away, and it’s on an orbit in the “Goldilocks zone” — not so close to its star that water boils away, nor so far that it’s perpetually icy. It was discovered by the small telescope on board Nasa’s Kepler spacecraft, which monitored the brightness of 150,000 stars for more than three years. Some stars underwent slight regular dimmings, caused by orbiting planets that transit in front of them, blocking out a bit of their light.

The Kepler data has already revealed many surprises. Our solar system may be far from typical. In some systems, planets as big as Jupiter are circling so close to their star that their “year” lasts only a few days. Some planets orbit binary stars — there would be two “Suns” in their sky. But we’d really like to see these planets directly — not just their “silhouettes” as they pass in front of their parent star. And that’s hard. To realise just how hard, suppose an alien astronomer with a powerful telescope was viewing the Earth from 30 light years away — the distance of a nearby star. It would seem, in Carl Sagan’s phrase, a “pale blue dot,” very close to a star (our Sun) that far outshines it: a firefly next to a searchlight.