EDINBURGH, Scotland — Some interstellar bullying appears to be going on in deep space, and our very own galaxy is the target. Scientists say the Milky Way is being pulled apart with “extreme violence” — by another galaxy! It’s being twisted and deformed through the gravitational force of a smaller city of stars, their research shows.
The discovery turns on its head the long-held belief that the Milky Way is relatively static, according to the study by researchers at the Edinburgh University. It’s being re-shaped by the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky way, some 168,000 light-years from Earth.
The study has implications for the spiral shaped disc of stars and planets, including Earth and the solar system.
“Our findings beg for a new generation of Milky Way models, to describe the evolution of our galaxy,” says lead author Dr. Michael Petersen, of Edinburgh University in a university release.
Petersen and colleagues show that the LMC crossed the Milky Way’s boundary around 700 million years ago — recent by cosmological standards. Due to its large dark matter content it strongly upset its fabric and motion as it fell in. This is the mysterious “glue” that holds galaxies together. It’s invisible, as it doesn’t emit, reflect or absorb light.
The effects are still being witnessed today and should force a revision of the birth of the Milky Way. The LMC is visible as a faint cloud in the southern hemisphere’s night skies. It’s named after the 16th century Portuguese explorer Ferdinand Magellan.
Previous research has revealed the LMC, like the Milky Way, is surrounded by a halo of dark matter.
LMC’s dark matter halo pulling Milky Way with incredible force
The study, published in Nature Astronomy, describes how it warped our galaxy’s motion. It used a sophisticated statistical model that calculated the speed of the Milky Way’s most distant stars.
Researchers say the enormous attraction of the LMC’s dark matter halo is pulling the Milky Way disc at 71,600 mph, or 20 miles a second. It’s being twisted in the opposite direction towards the constellation Pegasus in the northern sky.
To their surprise the Milky Way was not moving in the direction of the LMC’s current location as previously thought, but a point in its past trajectory. This is because the LMC, powered by its massive gravitational force, is floating away at the even faster speed of 800,000 mph, or 230 miles a second.
It’s been likened to the Milky Way trying hard to hit a fast moving target, but not aiming very well.
‘Discovery breaks spell that our galaxy is in equilibrium state’
The study will help scientists develop new modeling techniques that capture the strong dynamic interplay between the two galaxies.
“We were able to show that stars at incredibly large distances – up to 300,000 light-years away – retain a memory of the Milky Way structure before the LMC fell in, and form a backdrop against which we measured the stellar disc flying through space, pulled by the gravitational force of the LMC,” says Petersen.
The astronomers now plan to find out the direction from which the LMC first fell in, and the exact time it happened. This will reveal the amount and distribution of dark matter in the Milky Way and the LMC with unprecedented detail.
“This discovery definitely breaks the spell that our galaxy is in some sort of equilibrium state,” explains co-author, Jorge Penarrubia, also a professor at Edinburgh. “Actually, the recent infall of the LMC is causing violent perturbations onto the Milky Way. Understanding these may give us an unparalleled view on the distribution of dark matter in both galaxies.”
Last year, a Durham University team warned the LMC will destroy Earth in about 2 billion years time – by re-awakening the Milky Way’s dormant black hole.
SWNS writer Mark Waghorn contributed to this report.