the Milky Way

Our galaxy might be way more vast than we thought

Contributed by
May 31, 2018

Most Earthlings know we live in an immense rotating spiral disk glowing with 200 billion stars — but just how immense could actually blow your mind.

Astronomers used to think the Milky Way spanned 100,000 light-years (not what you’d call microscopic even in the vastness of space). Several years ago, new research expanded it to 150,000, but now, an even newer discovery puts our galaxy at no less than 170,000 and possibly 200,000 light-years across.

Exactly how vast is that? Even if you could ride the Millennium Falcon at the speed of light like Han Solo bragged, the trek from one side to the other would still take 200,000 years. Humans first walked the Earth so many eons ago. That’s still nothing compared to the alternative. If you didn’t have a supercharged spaceship and instead drove across at an average speed of 60 miles an hour, try 2 trillion years. Backtrack that far in time and our 13.8 billion-year-old universe was nowhere close to existing yet. The Big Bang wouldn’t even happen for... you get the point.

By using star atlases to study the chemistry, especially metallicity, of thousands of stars in the outer reaches of the galactic plane extending through the middle of the disk, researchers at the Canary Islands Institute of Astrophysics and the National Astronomical Observatories of Beijing were able to rethink our galaxy. They observed stars on the fringe of the Milky Way share the chemical DNA of those further in. Because of this, they should be considered part of our galaxy. Stars burning in the darkness that far out mean that the galaxy is more expansive than we ever thought.

NASA map of the Milky Way

NASA map of hte Milky Way. Can you find the sun? Credit: NASA

"We were able to confirm that some stars of the outermost regions in the plane belong to the disk," researcher Martin Lopez-Corredoira told NBC Mach, adding, "Although we have increased the size of the galactic stellar disk, the number of stars and the total mass of the galaxy [are] not significantly affected because the outermost disk... has a very low density of stars."

What the findings recently published in the journal Astronomy & Astrophysics also mean is that the disc of Milky Way is more structurally complex than previously assumed. The more we shed light on how spiral galaxies like our own came into being, the more scientists will be able to elucidate about the processes within them, including how elements emerge from nascent stars and scatter through the void, making their way into the chemical composition of planets and hypothetical life on those planets.

With evidence that some stars are three to four times the distance the sun was thought to be from positioned at (half the galactic radius), new research has also placed our star closer to the galactic nucleus. Rest assured that doesn’t mean we’re going to get devoured by a supermassive black hole.

(via NBC Mach)

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