When Worlds Collide

Here's a cheery thought: one day our galaxy may collide with nearby dwarf galaxies and come to pieces.

It may not happen soon. But someday, somehow, many researchers have suggested, our galaxy will meet its doom.

Or will it?

According to a new EurekaAlert article, there's actually a good reason why the Milky Way is unlikely to ever become intergalactic mincemeat. According to a new mathematical model, "instead of destroying a galaxy, these collisions 'puff up' a galactic disk, particularly around the edges, and produce structures called stellar rings."

The process of intergalactic smash-ups is, predictably, complex. It starts with the notion that ubiquitous dark matter forms a set of webs throughout the universe. Large galaxies like the Milky Way are enmeshed in strands of dark matter, while smaller satellite galaxies "flow along strands of the web, and get pulled into orbit around large galaxies such as our Milky Way."

What happens if a satellite galaxy whacks into our beloved Milky Way? According to EurekaAlerts, the news is good: "The satellite galaxy would gradually disintegrate, while its gravity tugged at the larger galaxy's edge, drawing out stars and other material. The result would be a flared galactic disk such as that of the Milky Way, which starts out narrow at the center and then widens toward the edges."

In other words -- it was earlier interactions with satellite galaxies that gave our Milky Way its lovely girlish figure. And, as it turns out, our tiny neighbors pose no threat to our galactic well-being, even untold millennia into the future.

Photo courtesy of NASA