Scientists Say This Galaxy Study Shows the Milky Way Is a 'Living, Breathing Beast'
The ESA's Gaia satellite is the gift that just keeps on giving—not only has it given astronomers and astrophysicists a super-accurate star map of the Milky Way galaxy and opened up the possibility of finding alien civilizations, it's now responsible for the discovery that the Milky Way may have experienced a galaxy-wide 'ripple' that knocked it out of its equilibrium between 300 and 900 million years ago.
Scientists have already proven the existence of gravitational ripples (and handed out Nobel Prizes for their discovery), but this situation was a bit different.
The Milky Way apparently passed close enough to the Sagittarius Dwarf Elliptical Galaxy, a satellite galaxy to the Milky Way, that the gravity of Sagittarius caused the Milky Way to become knocked off balance.
According to Teresa Antoja, one of the authors of a new study published on arXiv: "We have here provided the clearest evidence that our own Galaxy disk has suffered from perturbations, bringing it to an out-of-equilibrium state, which may well be due to the interaction with an external satellite galaxy."
It's a bit disturbing to imagine that the giant, 100,000 light-year disc of our galaxy can become "perturbed" by anything, but it's a fact we may have to get used to.
"This work shows that the stellar disk of the Milky Way is a dynamically active place, where spiral arms and the Galactic bar leave their marks on the orbits of stars like ripples in a pond-a pond that has perhaps recently felt the splash of a small stone in the form of a merging dwarf galaxy," said study author Stacy McGaugh.
"It is a living and breathing beast that is sensitive to being poked and prodded and even tickled a little bit."
We'll keep our eyes peeled for new discoveries from the Gaia data, but in the meantime, why not learn about the invisible supermassive black holes wandering around the Milky Way?