BrainStuff Classics: Why Is Our Galaxy Warped?

Our galaxy isn't a flat disk -- it's warped like melted vinyl record. Learn how researchers discovered this and why they think it happened in this classic episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio.

Speaker 2 (00:06):
Hey brain Stuff, Lauren vogel Bomb here with another classic
episode from the archives. This one gets into astronomy research
that has let us learn more about the shape of
our Milky Way galaxy and why it's bent like a
damaged vinyl record. Hey rain Stuff, Lauren vogel Bomb here.
Imagine standing in a dense woodland. How would you know

(00:28):
the size and shape of that forest? From your limited viewpoint?

Speaker 1 (00:31):
Not seeing the woods for the trees is a good
analogy for what astronomer's experience when trying to assess the
shape and size of our Milky Way galaxy. We occupy
a small star system embedded inside the Milky Way's disc.
It's not like we can fly above the galactic plane
to peak at our galaxies overall shape, although how cool
would that be. Our researchers, however, were determined to figure

(00:51):
out the true shape of the Milky Way while staying
embedded inside of it, and they have. Here's how they
did it. A team from the National Astronomical Observance Tories
of the Chinese Academy of Sciences that's the NAOC and
Macquarie University in Australia studied the one thousand, three hundred
and thirty nine bright pulsating stars called Cepheid variables to
create a three D map of the disc of our galaxy.

(01:13):
What they found came as a surprise. We live in
a warped galaxy. Astronomer and research collaborator Richard de Grace
said in a statement, Oh, we usually think of spiral
galaxies as being quite flat, like Andromeda, which you can
easily see through a telescope. But our galaxy isn't like Andromeda.
It has an S shaped bend that gets more twisted
the farther you move away from the galactic center. At

(01:36):
this bend, the galaxy's gravitational poll becomes weaker, making it
look like an old vinyl record that's become warped. The study,
which has been published in the journal Nature Astronomy, used
data from NASA's Wide Field Infrared Survey Explorer to precisely
determine the locations of the cepheids throughout our galactic disc
and turned them into a powerful tool to cut through
the dust, gas, and other stars that are obscuring our view.

(01:58):
Chen Xiadienne RENAOC and the lead author of the study,
said in a press release, it's notoriously difficult to determine
distances from the Sun two parts of the Milky Way's
added gas disc without having a clear idea of what
the disc actually looks like. However, we recently published a
new catalog of well behaved variable stars known as classical cepheids,
for which distances as accurate as three to five percent

(02:20):
can be determined. Cepheids are young stars that are four
to twenty times the mass of our Sun, and they
live fast and die young, consuming all their fuel in
the span of only a few million years, all while
burning up to one hundred thousand times brighter than our star.
But what they lack in life span they make up
or in regular pulses in brightness that can be used
by astronomers to accurately measure their distances, and in this case,

(02:43):
they acted as tracers to map out the warped milky
Way disc. Although the milky Way doesn't conform to the
standard flat disc exhibited by other spiral galaxies like Andromeda,
it's not alone. From earlier observations, the researchers identified a
dozen other galaxies with a similar S shaped bend, which
have given them a clue as to why our galaxy
is warped. Blue Chow, co author of the study, said,

(03:05):
combining our results with those other observations, we concluded that
Milky Way's warped spiral pattern is most likely caused by
torques or rotational forcing by the massive inner disc. Basically,
the orbital motions in the massive central region of the
Milky Way gravitationally bully the less massive outer regions, causing
them to buckle and bend out of shape. Ultimately, this

(03:28):
new finding could help us better understand the dynamics of
orbital motions inside the Milky Way, thereby providing a glimpse
of how our galaxy evolved. Today's episode is based on
the article our Milky Way is Warped Like an old
Vinyl record on HowStuffWorks dot.

Speaker 2 (03:45):
Com, written by Ian O'Neil. Brain Stuff is production by
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