Galactic Chaos: Our neighbouring galaxy is falling apart, scientists warn

Nearly 200,000 light-years from Earth, the Large Magellanic Cloud, a satellite galaxy of the Milky Way, floats in space, in a long and slow dance around our galaxy. (Image: NASA)

Sometimes, even galaxies close to us face hard times. A quiet neighbour of the Milky Way, the Small Magellanic Cloud (SMC), appears to be falling apart. And scientists say they didn’t see it coming.

Pulled by Its Larger Companion, the LMC

The SMC is about 200,000 light-years from Earth. It’s a dwarf galaxy that orbits our Milky Way galaxy. But it now seems to be in real trouble. According to a new study published on April 10 in The Astrophysical Journal Supplement Series, another galaxy may be to blame.

Researchers believe the SMC is being pulled by the Large Magellanic Cloud (LMC). The LMC is SMC’s much bigger companion. The team says this gravitational tug could be slowly tearing the SMC apart.

Lead researcher Kengo Tachihara from Nagoya University, Japan, admitted their surprise. “At first, we thought our data had some error,” he said. “But when we looked again, the results were very clear.”

Stars Moving in Strange Directions

The team studied data from ESA’s retired Gaia spacecraft. They discovered that stars in the SMC were moving in opposite directions. “It’s as if something is pulling them apart,” Mr Tachihara explained.

Some stars were heading toward the LMC. Others were moving away from it. This suggests that the SMC might be slowly losing its shape. The researchers believe the LMC’s strong pull could be the reason.

That wasn’t the only surprise. The study found something else unusual. The large stars within the SMC are not rotating as expected. Normally, stars rotate around a galaxy’s centre. But in this case, that rotation seems to be missing.

What It Means for Our Galaxy’s History

The lack of rotation could affect what we know about the SMC. Mr Tachihara said it may change past calculations of galactic movements. This includes the history of the Milky Way, the SMC and the LMC.

“If there is no rotation, our models need revising,” he explained. It could mean we’ve misunderstood the SMC’s mass or past collisions.

The SMC and LMC are part of a group of about 30 nearby galaxies. The SMC is only 7,000 light-years wide, while the Milky Way spans 100,000 light-years. The SMC completes an orbit around the Milky Way every 1.5 billion years.

Despite its size, the SMC is very bright. It’s even visible to the naked eye from the Southern Hemisphere. Because of this, it gives scientists a rare chance to study galaxy behaviour.

Learning from a Neighbour We Can See

“We cannot see the Milky Way from the outside,” Mr Tachihara said. “But we can study nearby galaxies like the SMC and LMC in detail.”

He added that this study helps connect star formation with stellar motion. Watching these galaxies closely offers clues about how stars behave across time.

The SMC’s slow tearing apart may not be fast or dramatic. But it offers a deep insight into the life of galaxies. Even those in our own corner of the cosmos are not safe from change.