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Astronomy

Detailed map of the Milky Way

Our galaxy seen from the Southern Hemisphere: the distance and brightness of 1.14 billion stars

A. Fuji/ESO Our galaxy seen from the Southern Hemisphere: the distance and brightness of 1.14 billion starsA. Fuji/ESO

On September 13, 2016, the European Space Agency (ESA) released to astronomers and the general public preliminary data on the largest-ever survey of stars in the Milky Way, the galaxy that is home to the Solar System. The Gaia satellite, which makes a large orbit around the Sun, has been taking high-resolution photographs of the entire sky since July 2014. By September 2015, the images obtained by the mission enabled calculation of the distance and brightness of 1.14 billion stars, roughly 1% of the estimated total for the galaxy. In comparing Gaia data with sky charts done in the 1990s by the ESA’s Hipparcos satellite, astronomers were able to determine with unprecedented precision the distance and movements of 2.5 million stars in the Milky Way. Five Brazilians take part in the Gaia project, which should provide data on the precise distance of more stars by late 2017. In early September 2016, another group – whose members include astronomers Silvia Rossi and Rafael Santucci, both of the University of São Paulo (USP) – published calculations on the ages of 130,000 Milky Way stars. The results, which help understand galaxy formation, show that the oldest stars are in the center while the youngest are on the edge (Nature Physics, September 5, 2016).

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