Seen here is an artist’s impression of how the Milky Way galaxy would look seen from almost edge on and from a very different perspective than we get from the Earth. Image Credit: Wikimedia Commons.

The Milky Way’s Outer Disk is Vibrating

Astronomers using data from the GAIA telescope have discovered that the outermost disk of our galaxy the Milky Way vibrates.


An international team led by scientists at Lund University in Sweden has discovered that the Milky Way’s outer disk vibrates. Scientists used data from the Gaia space telescope to make the discovery. But before you think about aliens and anything related to that, the ripples scientists identified were caused by a dwarf galaxy, now caught in the constellation Sagittarius. When it passed by hundreds of millions of years ago, this galaxy shook the Milky Way. There are between 100 billion and 400 billion stars in our cosmic home, the Milky Way, and hundreds of billions of planets in it. Based on our best estimates, there are between six and ten billion Earth-like planets.

According to astronomers, the galaxy we live in emerged from a rotating cloud of hydrogen and helium gas 13.6 billion years ago. Stars, like our sun, were formed as a result of the gas accumulating in a rotating disk over billions of years. New research published in Monthly Notices of the Royal Astronomical Society describes the stars in the galactic disk’s outer regions. “We can see that these stars wobble and move up and down at different speeds. When the dwarf galaxy Sagittarius passed the Milky Way, it created wave motions in our galaxy, a little bit like when a stone is dropped into a pond”, Paul McMillan, the astronomy researcher at Lund Observatory who led the study, explains. Scientists were able to examine more of the Milky Way’s disk by using data collected by the European space telescope Gaia.

Using ripple measurements in different parts of the disc, researchers have begun to piece together clues about the history of Sagittarius and its orbit around our galaxy. According to Paul McMillan, Sagittarius was significantly bigger 1-2 billion years ago, perhaps around 20 percent of the Milky Way’s mass. Data from Gaia allowed researchers to study an astonishing amount of the Milky Way. Since 2013, the telescope has measured approximately two billion stars’ movements across the sky and 33 million stars’ movements toward and away from us. Geologists use seismic waves traveling through the Earth to study the Earth’s structure, and this new discovery enables us to do the same with the Milky Way. We will learn a great deal about our home galaxy and its evolution through this type of “galactic seismology,” concludes Paul McMillan.


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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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