Space

Telescopes keep getting sharper and space missions keep travelling further, yet nobody has found confirmed evidence of life beyond Earth. An international team of researchers suggests that part of the problem may lie in how we look: science worries a lot about claiming life where there is none, and far less about missing real traces. Statistics students call this a false negative – and at the end you can check whether you have the eye of an alien-trace hunter.

Lie on a blanket somewhere far from the city and one thing becomes obvious within a minute: the stars are not scattered evenly. Some patches of sky are crowded, others look almost empty, and a pale band runs straight across the middle. The answer to that one naive question leads through gravity, the shape of the Milky Way, three families of galaxies and a collision already pencilled in for ten billion years from now – and at the end you can check what kind of sky-watcher you are.

Star catalogues hand out ages to several decimal places, and the numbers look as solid as a temperature reading. They are not. For decades the models behind them simply assumed how much helium a star holds, because nobody knew how to measure it. The EU-funded CartographY project set out to stop assuming, and in the process it showed how far precision can drift from accuracy — the difference between treating astrophysics as a method and treating it as a view.