Editorial: Nasa Kepler shows a reality even stranger than science fiction

After four years, Nasa’s Kepler Mission – an orbiting space-telescope looking for other worlds like our own – has found a staggering 2,700-plus “planetary entities”.

So far, only slightly more than 100 are confirmed as definite planets, but the majority are expected to pass the test.

But it is not just the huge number of potential planets that is startling scientists. It is also their sheer weirdness. Some are unfeasibly dense, their iron terra firma washed by molten metal seas; others are so light they would, like polystyrene, float on water; others still come in at several times the vastness of Jupiter.

All of which has theoreticians tearing up their assumptions and heading back to the scientific drawing board. What Kepler has notably not found, though, is an Earth-sized planet in a “habitable zone” – neither so far from a star as to be frozen, nor so near as to be burned dry. No matter. The search has rewards enough.