At least two intergalactic interlopers are hurtling through our galaxy at more than 700 kilometres per second. These stars from outside the Milky Way are among almost 30 runaways that have been spotted in a treasure trove of data from the European Space Agency's Gaia satellite mission. The Gaia satellite has been charting the stars for years in an effort to make the largest 3D map of our galaxy. On 25 April, Gaia released its second batch of data on 1.7 billion stars. For a subset of 7 million, Gaia measured how fast they are moving away from or towards Earth. Of these, Tommaso Marchetti and colleagues at Leiden University in the Netherlands looked for hypervelocity stars, those travelling at speeds greater than 450 kilometres per second. They found 165 candidates. The team calculated that 28 have a greater than 50 per cent chance of escaping our galaxy's gravitational pull. "They are basically flying away forever from the Milky Way," says Marchetti. A handful of these unbound stars