3 Ways the Milky Way Will Change During Your Lifetime


{♫Intro♫} Compared to a human lifetime, timescales in
space are enormous. So it’s easy to imagine that our Galaxy
is basically frozen during the handful of decades that we’re alive. After all, generations and generations of
our ancestors have looked at the same planets and constellations that we
see today. But, that being said, galaxies are really
dynamic, and the Milky Way is changing all the time. In fact, in your lifetime — let’s call
it a hundred years — it will undergo some pretty amazing changes. For one, it will probably grow — like, a
lot. According to a 2018 paper, spiral galaxies
like ours are steadily expanding at around 500 meters
per second. That’s roughly twice the speed of a jet! And if this rate also applies to the Milky
Way, that means it will grow about one point five billion kilometers over
the next century. That’s not just a statistic, either. This number can also teach scientists about
galactic evolution in general. See, the fact that these galaxies grow wasn’t
a total surprise. For years, scientists have known that, every
once in a while, they can eat up smaller galaxies that get captured by their gravity. But that 2018 paper was important because
it confirmed that this isn’t the only way these neighborhoods get bigger. They also expand because new stars are being
born — and in a pretty odd place, too. In this study, researchers observed two spiral
galaxies like ours. And after calculating how stars on the fringes
were moving, they concluded that these galaxies were growing because stars
were being born on their edges. Models had predicted this, but it was hard
to prove they were right just by looking at the Milky Way since, well, we’re inside it. So by looking at other galaxies, scientists were able to confirm their hypothesis. This finding was mainly strange because most
stars form toward the center of their galaxy. So this paper demonstrated that there can
still activity way out in the galactic outskirts. That means that, even if it never interacts
with another galaxy, the Milky Way will likely keep growing while
you’re alive — as long as it has enough gas around the edges
to make new stars. Of course, at this point in its life, our
Galaxy is making stars pretty slowly, churning out maybe one or two a year. But that means that in the course of your
lifetime, it could gain around a hundred new stars! Now, sure, for a place with at least a hundred
billion stars, that’s barely a sprinkling. Things have slowed down now that our Galaxy
is well into adulthood, at a healthy thirteen and a half billion years
old. It’s a long ways from its wild youth, about
nine billion years ago, when it was forming around a dozen stars a
year. Still, from a human perspective, a hundred
new stars is nothing to scoff at. And besides, understanding that number can
also teach scientists how the Galaxy has evolved. Because the thing is, the Milky Way’s star
formation hasn’t just tapered off — it’s been more of a rollercoaster. After that peak around nine billion years
ago, star formation dropped to a tenth of its previous rate. This shutdown happened around the same time
that our Galaxy formed its thick disk. Scientists aren’t exactly sure how the two
events are connected, but they think it’s possible that the formation
of this disk stirred things up and made the gas so hot that it stopped condensing
into stars. Fortunately, star formation has picked up
again since then although these days, things are pretty quiet. Still, that’s relatively normal for older
neighborhoods, like ours, that don’t have a lot of interaction with
other galaxies. Even so, the Milky Way is popping out the
occasional new star, as regions of dust condense and ignite. And over the course of a century, our Galaxy is likely to have dozens of new
studs of light. Finally, the Milky Way won’t just gain things
during your lifetime. It will also lose some. After all, the Milky Way’s new stars are
just the recycled remains of old ones — and in the next hundred years, it will likely
lose about as many stars as it gets. Two or three might even explode as supernovas. This will only happen to the really massive
stars, but when they die, they’ll spew their contents into space,
and some of the elements from their cores will be incorporated into new stars. As far as we know, the most recent supernova
in our Galaxy blew up around 140 years ago. But a 2006 estimate suggests that, on average,
the Milky Way has seen a supernova explode around every 50 years. So in a sense, it seems like we’re kind
of overdue for some fireworks. And scientists may have found the next culprit. They have their eyes on a triple-star system
nicknamed Apep, which is about eight thousand light-years
away and seems to be on the brink of explosion at least, based on what we can see of it. One of its stars is releasing streams of charged
particles at a speed that suggests it’s at the point of collapse. Thankfully, because of the way the star is
oriented, it shouldn’t do any harm to Earth even if we see evidence of that explosion
soon. And either way, cosmic “brinks” can be
human lifetimes, so it’s hard to say exactly when this thing
will go. We might not see evidence of its explosion
for another thousand years or more. Whether or not the Galaxy lights up with a
new supernova in the near future, the Milky Way is far from the frozen river
of stars that you see on a dark night. In your lifetime alone, dozens of stars will
blink in and out of existence, and the whole Galaxy will likely push its
own boundaries by more than a billion kilometers. And it’s not just cool to find events in
space on the scale of our lives. Understanding these short-term events also
helps us get a handle on how galaxies evolve and sort out what it’s
like to be in the galactic middle age. Thanks for watching this episode of SciShow
Space! The universe is super fascinating and can also be surprisingly accessible, and
we love getting to explore it with you. If you want to support the show and help us
keep making more free content like this, you can go to patreon.com/scishow. {♫Outro♫}

97 comments

OK, so if we were traveling through space in a 'ship', would there be different speeds in and out of galaxies? Like would we be traveling at a constant outside of the galaxy and as we neared it, get swept up in it's velocity and have to adjust? Or would it's stars & planets & bits just go around us like a storm? Or is the distance at that scale too miniscule to notice?

OK explain to me this…. If a new star forms at the edge of the galaxy, and the mass to create that new star >didn't> come from eating a smaller galaxy, how can you possibly equate that to the galaxy getting bigger? The star didn't appear out of nothing. You have a bunch of dust and gas, it collapses in on itself, and voila, new star. But the gas the star came from was >already part of the galaxy>. If anything, the galaxy itself >shrank> slightly. And the rest of the video was just dumb. The title was clickbait. I've been on the fence for past silliness and inaccuracies- made up my mind to remove scishow from my feed.

It growing bigger is relatively insignificant and totally unnoticeable! lol, CLICK BAIT #1
100 new stars? Gimme a break, that's like 100 grains of sand added to a pile of sand a mile high or whatever. CLICK BAIT #2!
Waiting for a supernova? Mind as well watch paint dry! CLICK BAIT #3
The truth is that to us, the Milky Way looks 99.9999999% the same that it has for 1000's of years! It is so static on our time scale that it mislead Einstein into thinking the entire universe was static and unchanging and thus him adding a cosmological constant to his relativistic field equations…his so called biggest blunder of his life! I really hate when these pin head pop science geeks come out with these hyperbolic claims of whatever only to find out that the reality is basically just a big yawnfest.
DOWN VOTED!

It's been two human lifetimes since the last supernova. I'm almost 40 years old–and it isn't rational at all–but let me tell you today I will be SUPER PISSED OFF if I don't get to see a supernova before I die! (I have been keeping my fingers crossed for Betelgeuse.)

“They grow”… isn’t the supermassive black hole in the center of every galaxy swallowing all of the matter?

Will my Minnesota Vikings win a Superbowl in the next 100 years? I'm 40 so I don't have much time left lol.

But… has not the star exploded already like a very long time ago and we just don't know it yet? The aftermath could be on the way and hit our solar system at any moment and it could be a catastrophe. It could end all life in our solar system!

"Ah-normous!" lol one thing, 500mph galactic expansion isn't twice the speed of a jet, that is the top speed of most jets I think. They cruise at 360moh going with the hetstream I'm pretty sure

Funny to think that, that star is possibly already nova-ed. The light evidence just hasn't reached us yet

Well of course it can't harm our solar system from that distance, and 8,000 lyrs away means if we see it explode then it already happened 8,000 lightyears ago and we are just seeing the light. Lol

"In your lifetime, let's call it a hundred years (said in an unconvincing manner)" ..
Me: Spits out cola… "yeah right."

This one was quite a stretch to turn a nothing topic into something. I don't think you succeeded. I would summarize this as clickbait.

The slides showing the exact same words the narrator is saying are irritiating. That's useless screen time.

"fortunately" star birth rate has picked up again… "fortunately" do we care? do we care if stars in our galaxy are being born or not? does stars not being born have any effect whatsoever on us? do words mean anything to you mr. script writer?

May 25th 2019 ~2200 hours; several people and I camping in Utah watched a line of 30-40 lights traveling in a line from west to east. Some lights seemed to vary it intensity. They traveled at a similar speed as the ISS crosses the sky to the naked eye. After this line passed 4 more lights came by together on the same trajectory and velocity.

Anyone know what we witnessed? I have guesses but can't find any information.

Twice the speed of a jet? Sorry, but you're discussing measurements that are literally astronomical, and you say twice the speed of a jet as if that were fast? Even assuming the fastest jet we've developed, on the scales you're discussing, that's almost nothing.

OK, but does the galactic barrier grow with it? If not, civilizations outside the barrier may be cut off from subspace communication with the rest of the galaxy.

Does it annoy anyone else when they use things like "the speed of a jet" to make things seem faster, even though it is minuscule on a galactic level

I am starting my own channel for astronomy! want to learn more? Check this page! http://unbouncepages.com/astronomy1/

"milky Way don't have alot of interaction with other galaxies".

– Large Magellanic Cloud: fine then I'll block you. And you can pay child support for the Small Magellanic Cloud. 😁

how underwhelming, "in your lifetime the milky way will grow 100 new stars, and also it will lose 100 old stars." Its like watching someone take a handful of sand from the beach, but also adding a handful of sand to the beach.

I don’t think we will ever get to observe the new stars which are being formed at the edge of our galaxy as the light they emit will take thousands of years to get to us

Thanks. Well presented. I was just wondering about new stars. Also wondering about galaxy clusters and how the expanding of the universe will drive away galaxies.

Now it's reached middle age the galaxy is planning to buy a sports car and have an affair with that hot young galaxy a few doors down

You know, that made me think of a silly thing – an interesting way to test the Fermi paradox would be to have telescopes sensitive enough to spot exoplanets in other galaxies, maybe we could observe hints of galaxy-wide colonization in ones older than ours?

show us visual illustrations of the galaxy changing!! its an audio visual medium for fricks sake I might as well listen to the radio than sit through this

Fair Bloody Dinkum mate that's not how to spell (kilometers) it's KILOMETRES! Bloody American spelling is ridiculous, changing spell for the sake of it, just so it's different from the real British dictionary.

Great! I am going to live 100 years, I am already 60, so that gives 160 years, as old as a Vulcan…live long and prosper! 😉

Please. Do no use kilometers when talking about universe stuff. It's completely irelevant measure which says nothing. More appropriate would be light years of course. Nobody knows what a million km means but everybode knows what a light year, light minute, light months, etc is.

Will grow 1.5 billion KM over the next century… sounds like a lot until ya realize that's roughly the distance from the sun to Saturn. In the grand scheme of things, kinda negligible.

and in 100 years our solar system travels 0.0765 of a lightyear around the galactic core, which means it takes our solar system 1300 years to travel 1 lightyear

I was hoping for something more interesting besides the galaxy growing a bit, and stars we can’t even see with the naked eye come and go.

It's annoying when someone wants to make a big deal out of a small deal.
The galaxy is 150,000 to 200,000 light years across.
If it grows 1.5 billion km in the next century … that's an increase of 0.016%.
BFD.

"…dozens of stars will blink in and out of existence." I don't particularly like this phrasing. It hit my brain in a way that felt like it implied that stars will blink both in and out of existence. I would have preferred .. maybe "or" instead of "and"?
ETA: Maybe it's that blink intrinsically implies both on and off (e.g. the verb to blink [close and open], or blinking lights [on and off])

I'm sorry Scishow, but this video was pure filler. I can imagine the crew realizing they had 6 minutes and some change to make a clip, so they frantically filled it with meaningless data. Astronomical evolution passes at such a glacial rate none of the things they talk about here are interesting or intriguing.

In my opinion scientist are completely arrogant about what they think they know. They are more than likely Clueless

Nothing is going to "wink out of existence". Things just change form. Most stars will become white dwarfs. In the event of a supernova/hypernova it'll change into either a black hole or a neutron star.

May I make a request? I’d be interested in seeing a video that talks about what we can see in space with the naked eye — farthest star, farthest galaxy, brightest object, youngest object, stuff like that. Apologies if this has been covered in other videos; I’ve watched a lot of them, but not all…

I don't get it.  There is dust and gas floating around.  It condenses and ignites.  Why is the galaxy bigger?  Wasn't the gas part of the galaxy?  What defines the boundary of a galaxy and how is affected by star formation?

From a galactic point of view, expansion of 1.5 billion km per century is negligible. That's not even one light year.

So "dark matter" has to exist because stars are going too fast to be in stable orbits… but the galaxy is expanding… so does that mean that the stars are actually moving outwards by more than we thought, bringing into doubt the need for dark matter? Probably not, I'm sure that someone smarter than me thought about this already.

why would existing mass in the form of gas on the edge of the galaxy condensing into a star make the galaxy grow?

Considering how immense gravitational pull affects space-time, our relative position will mean that we experience these things in a different time frame than the origins.

Am I the only one that wants to hear this guy just randomly say, "Hello, I'm Morgan Freeman, and you're watching Scishow." Tell me you can't picture that

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