From the most accurate parallax measurements, about ten per cent of the total, astronomers can directly estimate distances to individual stars. The new catalogue lists the parallax and velocity across the sky, or proper motion, for more than 1.3 billion stars.
With these accurate measurements it is possible to separate the parallax of stars – an apparent shift on the sky caused by Earth’s yearly orbit around the Sun – from their true movements through the Galaxy. For some of the brightest stars in the survey, the level of precision equates to Earth-bound observers being able to spot a Euro coin lying on the surface of the Moon. The new data release, which covers the period between 25 July 2014 and, pins down the positions of nearly 1.7 billion stars, and with a much greater precision. The first data release, based on just over one year of observations, was published in 2016 it contained distances and motions of two million stars. Gaia was launched in December 2013 and started science operations the following year.
It demonstrates the need for long-term projects to guarantee progress in space science and technology and to implement even more daring scientific missions of the coming decades.” “Gaia is an ambitious mission that relies on a huge human collaboration to make sense of a large volume of highly complex data.
