Everything in the Universe is spinning.
Spinning planets and their spinning moons
orbit around spinning stars, which orbit spinning
galaxies.
It’s spinning all the way down.
Consider that fiery ball in the sky, the Sun.
Like all stars, our Sun rotates on its axis.
You can’t tell because staring at the Sun
long enough will permanently damage your eyeballs.
Instead you can use a special purpose solar
telescope to observe sunspots and other features
on the surface of the Sun.
And if you track their movements, you’ll
see that the Sun’s equator takes 24.47 days
to turn once on its axis.
Unlike its slower poles which take 26.24 days
to turn.
The Sun isn’t a solid ball of rock, it’s
a sphere of hot plasma, so the different regions
can complete their rotation at different rates.
But it rotates so slowly that it’s an almost
perfect sphere.
If you were standing on the surface of the
Sun, which you can’t, of course, you would
be whipping around at 7,000 km/h.
That sounds fast, but just you wait.
How does that compare to other stars, and
what’s the fastest that a star can spin?
A much faster spinning star is Achenar, the
tenth brightest star in the sky, located 139
light-years away in the constellation of Eridanus.
It has about 7 times the mass of the Sun,
but it spins once on its axis every 2 days.
If you could see Achenar up close, it would
look like a flattened ball.
If you measured it from pole to pole, it would
be 7.6 Suns across, but if you measured across
the equator, it would be 11.6 Suns across.
If you were standing on the surface of Achenar,
you’d be hurtling through space at 900,000
km/h.
The very fastest spinning star we know of
is the 25 solar mass VFTS 102, located about
160,000 light-years away in the Large Magellanic
Cloud’s Tarantula Nebula - a factory for
massive stars.
If you were standing on the surface of VFTS
102, you’d be moving at 2 million km/h.
In fact, VFTS 102 is spinning so quickly,
it can just barely keep itself together.
Any faster, and the outward centripetal force
would overcome the gravity holding its guts
in, and it would tear itself apart.
Perhaps that’s why we don’t see any spinning
faster; because they couldn’t handle the
speed.
It appears that this is the fastest that stars
can spin.
One other interesting note about VFTS 102
is that it’s also hurtling through space
much faster than the stars around it.
Astronomers think it was once in a binary
system with a partner that detonated as a
supernova, releasing it into space like a
catapult.
Not only stars can spin.
Dead stars can spin too, and they take this
to a whole other level.
Neutron stars are what you get when a star
with much more mass than the Sun detonates
as a supernova.
Suddenly you’ve got a stellar remnant with
twice the mass of the Sun compressed down
into a tiny ball about 20 km across.
All that angular momentum of the star is retained,
and so the neutron star spins at an enormous
speed.
The fastest neutron star ever recorded spins
around 700 times a second.
We know it’s turning this quickly because
it’s blasting out beams of radiation that
sweep towards us like an insane lighthouse.
This, of course, is a pulsar, and we did a
whole episode on them.
A regular star would be torn apart, but neutron
stars have such intense gravity, they can
rotate this quickly.
Over time, the radiation streaming from the
neutron star strips away its angular momentum,
and it slows down.
Black holes can spin even faster than that.
In fact, when a black hole is actively feeding
from a binary companion, or a supermassive
black hole is gobbling up stars, it can rotate
at nearly the speed of light.
The laws of physics prevent anything in the
Universe spinning faster than the speed of
light, and black holes go right up to the
edge of the law without breaking it.
Astronomers recently found a supermassive
black hole spinning up to 87% the maximum
speed permitted by relativity.
If you were hoping there are antimatter lurking
out there, hoarding all that precious future
energy, I’m sorry to say, but astronomers
have looked and they haven’t found it.
Just like the socks in your dryer, we may
never discover where it all went.
What other mysteries in astronomy and physics
fascinate you.
Let me know your suggestions for future episodes.
In our next episode, we wonder what the Universe
does when we’re not looking.
Oh, and make sure you stick around for the
blooper.
Is this the part where your brain shuts off,
and you start looking around for new videos
to watch?
I’m always going blah blah Patreon this
and blah blah community that?
Wait a second and seriously consider if you’re
getting value from all these space videos,
articles, podcasts we’re making.
For as little as a dollar a month, you can
support us directly.
And in exchange, we’ll remove all the advertising
from Universe Today, and even invite you into
our inner circle community of members who
support us in making everything.
As of right now, there are 530 amazing supporters.
Directly funding the work that we do on Universe
Today.
They get to see our videos in advance, hangout
with me and the team, and see unreleased material.
And they never see an ad on Universe Today.
We’d like to thank Adit Abrasion, Nick Torelli,
David Skipper, and the rest of the members
who support us in making great space and astronomy
content.
Want to get in on the action?
Go to patreon.com/universetoday
