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Milky Way
The Milky Way. | Getty Images
Astronomy

The Milky Way Devoured Another Galaxy 10 Billion Years Ago

New data from the European Space Agency explains why some stars are going the wrong way, galactically speaking.

On the left, a face-on view shows the spiral structure of the Galactic Disc, where the majority of stars are located, interspersed with a diffuse mixture of gas and cosmic dust. The disc measures about 100 000 light-years across, and the Sun sits about half way between its center and periphery. On the right, an edge-on view reveals the flattened shape of the disc. Observations point to a substructure: a thin disc some 700 light-years high embedded in a thick disc, about 3000 light-years high and populated with older stars. The edge-on view also shows the Galactic Bulge, located in the central portion of the Milky Way and hosting about 10 billion stars. ESA
Artist's impression of debris of the Gaia-Enceladus galaxy. Gaia-Enceladus merged with our Galaxy during its early formation stages, 10 billion years ago, and its debris can now be found throughout the Galaxy. ESA