00:00When galaxies collide with one another, they are absolutely cataclysmic events, and experts
00:09believe our galaxy, the Milky Way, was part of one of these at some point in its history.
00:14Now recent data from the Gaia satellite is showing astronomers what might have happened
00:18and explains some anomalies we've detected in the past.
00:21The Milky Way's galactic disk has an S-shaped bend, something first noticed way back in
00:25the 1960s.
00:26For decades, experts weren't sure why this bend existed, or why it stretched nearly a
00:31quarter of the way around the entire galaxy, including altering the movement of tens of
00:35thousands of stars.
00:37Now they say it's likely because this is the resulting shockwave propagating throughout
00:41the galaxy, the remnants of a previous galactic collision.
00:44They say there are two distinct movements happening in the galactic ring, one back and
00:48forth and the other up and down.
00:50They say this is similar to how ocean waves move, independent of a tsunami underneath.
00:55However, this one doesn't drag water, but entire star clusters, forcing them to deviate
00:59some 6 to 9 miles from their intended paths every second.
01:03Recent research suggests that the Milky Way's last galactic collision occurred just 3 billion
01:07years ago, meaning Earth was likely already around when it happened.
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