Milky Way still in thrall of a 900 million-year-old cosmic collision
The Milky Way galaxy is still enduring the effects of a near collision that took place sometime in the past 300-900 million years and set millions of stars moving like ripples on a pond, scientists say. The European Space Agency (ESA)'s star mapping mission, Gaia, discovered the pattern of movement in stars in the Milky Way disc -- one of the major components of our galaxy. The pattern was revealed because Gaia not only accurately measures the positions of more than a billion stars but also precisely measures their velocities on the plane of the sky. For a subset of a few million stars, Gaia provided an estimate of the full three-dimensional velocities, allowing a study of stellar motion using the combination of position and velocity, which is known as 'phase space'. Read Complete Article Article Source >> Business Standard