Gaia: scientists take a step closer to revealing origins of our galaxy

An international team of astronomers, led by the University of Cambridge, announced the most detailed ever catalogue of the stars in a huge swathe of our Milky Way galaxy. Gaia is measuring the distances of hundreds of millions of objects that are many thousands of light years away, at an accuracy equivalent to measuring the thickness of hair at a distance of more than 2000 kilometres Floor van Leeuwen The measurements of stellar positions, movement, brightness and colours are in the third early data release from the European Space Agency's Gaia space observatory, and are now publicly available. Initial findings include the first optical measurement of the acceleration of the Solar system. Launched in 2013, Gaia operates in an orbit around the so-called Lagrange 2 (L2) point, located 1.5 million kilometres behind the Earth in the direction away from the Sun. At L2 the gravitational forces between the Earth and Sun are balanced, so the spacecraft stays in stable position, allowing long-term essentially unobstructed views of the sky. The primary objective of Gaia is to measure stellar distances using the parallax method. In this case astronomers use the observatory to continuously scan the sky, measuring the apparent change in the positions of stars over time, resulting from the Earth's movement around the Sun.