Milky Way's secrets revealed by space probe map
The Gaia space probe unveiled its latest discoveries on Monday in its quest to map the Milky Way in unprecedented detail, surveying nearly two million stars and revealing mysterious "starquakes" which sweep across the fiery giants like vast tsunamis. The mission's third data set, which will be released at 6pm Hong Kong time to eagerly waiting astronomers around the world, "revolutionises our understanding of the galaxy", the European Space Agency (ESA) said. "It's the Swiss Army knife of astrophysics – there is not a single astronomer who does not use its data, directly or indirectly," said Francois Mignard, a member of the Gaia team. Some of the map's new insights are close to home, such as a catalogue of more than 156,000 asteroids in our Solar System "whose orbits the instrument has calculated with incomparable precision," Mignard said. But Gaia also sees beyond the Milky Way, spotting 2.9 million other galaxies as well as 1.9 million quasars – the stunningly bright hearts of galaxies powered by supermassive black holes. The Gaia spacecraft is nestled in a strategically positioned orbit 1.5 million km from Earth, where it has been watching the skies since it was launched by the ESA in 2013. The probe is equipped with two telescopes as well as a billion-pixel camera, which captures images sharp enough to gauge the diameter of a human hair at a distance of 1,000km. It also has a range of other instruments that allow it to not just map the stars, but measure their movements, chemical compositions and ages. The observation of "starquakes", massive vibrations that change the shape of the distant stars, was "one of the most surprising discoveries coming out of the new data", the ESA said. Gaia was not built to observe starquakes but still detected the strange phenomenon on thousands of stars, including some that should not have any – at least according to our current understanding of the universe. "Gaia is opening a gold mine for 'asteroseismology' of massive stars," said Gaia member Conny Aerts. Around 50 scientific papers were published alongside the new data, with many more expected in the coming years. Gaia's observations have fuelled thousands of studies since its first dataset was released in 2016. The second dataset in 2018 allowed astronomers to show that the Milky Way merged with another galaxy in a violent collision around 10 billion years ago. The final data set will be released in 2030, after Gaia finishes its mission surveying the skies in 2025. (AFP)