Yahoo News Something huge nearly hit our galaxy and set millions of stars ‘rippling like a pond’
A star-mapping telescope has found that the stars in our Milky Way galaxy are ‘rippling’ like the surface of a pond – and it’s due to a galactic near-miss.
Researchers now believe that another dwarf galaxy may have ‘grazed’ our Milky Way in the past 300-900 million years (recent history in galactic terms) – and set the galaxy’s disc ‘jiggling’.
The strange pattern of movement was spotted by ESA’s star-mapping mission, Gaia, which mapped the motion of more than a billion stars – including their velocities.
It showed a strange pattern of motion, like a ‘snail shell’ in the Milky Way’s disc.
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Teresa Antoja from Universitat de Barcelona, Spain, who led the research couldn’t quite believe her eyes when she first saw it on her computer screen.
She said, ‘I was a bit shocked and I thought there could be a problem with the data because the shapes are so clear.’
Antoja and her team believe the ‘ripples’ could have been caused by a close encounter with the Saggitarius dwarf galaxy.
Sagittarius’s last close encounter with the Milky Way place it sometime between 200 and 1000 million years ago, which is almost exactly what Teresa and colleagues calculated as an origin for the beginning of the snail shell-like pattern.
The scientists plan to investigate this galactic encounter as well as the distribution of matter in the Milky Way by using the information contained in the snail shell shape.
Timo Prusti, Gaia project scientist at ESA said, ‘This is exactly the kind of discovery we hoped would come from the Gaia data. The Milky Way has a rich history to tell, and we are starting to read that story.’
