A major event in the formation of the Milky Way
Artist's impression of the merger between the Gaia-Enceladus galaxy and our Milky Way, which took place during our Galaxy's early formation stages, 10 billion years ago.
Astronomers uncovered this major event in the formation history of the Milky Way after discovering an 'odd collection' of stars that move along elongated trajectories in the opposite direction to the majority of the Galaxy's other hundred billion stars, including the Sun. The discovery was possible thanks to the second data release of ESA's Gaia mission and its extraordinary precision.
The positions and motions of the stars in Gaia-Enceladus (represented with yellow arrows) in this early phase of the merger are based on a computer simulation that models a similar encounter to that uncovered by Gaia.
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