They're like giant atom cores,

Kilometers in diameter,

Unbelievably dense and violent,

But how can something like this even exist!

The life of a star is dominated by two forces being in balance

It's own gravity,

and the radiation pressure of it's fusion reaction.

In the core of stars, hydrogen is fused into helium.

Eventually, the hydrogen in the core is exhausted.

If the star is massive enough, helium is now fused into carbon.

The cores of these massive stars become layered like onions,

as heavier and heavier atomic nuclei build up at the center.

Carbon is fused into neon, which leads to oxygen, which leads to silicon.

Eventually, the fusion reaction hits iron, which can not fuse into another element.

When the fusion stops, the radiation pressure drops rapidly.

The star is no longer in balance.

and if it's core mass exceeds about 1.4 solar masses, a catastrophic collapse takes place.

The outer part of the core reaches velocities of up to 70,000 kilometers a second,

as it collapses towards the center of the star.

Now, only the fundamental forces inside an atom are left to fight the gravitational collapse.

The quantum mechanical repulsion of electrons is overcome,

and electrons and protons fuse into neutrons packed as densely as an atomic nucleus.

The outer layers of the star are catapulted into space, in a violent supernova explosion.

So, now we have a neutron star!

It's mass is between 1 and 3 suns, but compressed to an object about 25 kilometers wide!

And 500,000 times the mass of Earth, in this tiny ball, that's roughly the diameter of Manhattan.

It's so dense that one cubic centimeter of neutron star, contains the same mass as an iron cube 700 meters across.

That's roughly 1 billion tones, as massive as mount Everest, in a space the size of a sugar cube.

Neutron star gravity is pretty impressive too!

If you were to drop an object from 1 meter over the surface, it would hit the star in one microsecond,

and accelerate up to 7.2 million km/hour.

The surface is super flat, with irregularities of 5 millimeters maximum,

with a super thin atmosphere of hot plasma.

The surface temperature is about 1 million Kelvin, compared to 5,800 kelvin for our sun.

Lets look inside the neutron star!

The crust is extremely hard, and is most likely made of an iron atom nuclei lattice,

with a sea of electrons flowing through them.

The closer we get to the core, the more neutrons and the fewer protons we see

until there's just an incredibly dense soup of indistinguishable neutrons.

The cores of neutron stars are very, very weird.

We are not sure what their properties are, but our closest guess is super fluid neutron degenerate matter,

or some kind of ultra dense quark matter called: quark-Gluon plasma.

That does not make any sense in the traditional way, and can only exist in such an ultra extreme environment.

In many ways, a neutron star is similar to a giant atom core.

The most important difference is that atom cores are held together by strong interaction, and neutron stars by gravity.

As if all this wasn't extreme enough lets take a look at a few other properties.

Neutron stars spin very very fast, young ones, several times per second.

And if there's a poor star near by to feed a neutron star, it can rotate up to several hundred times per second.

Like the object PSRJ1748-2446ad, it spins at approximately 252 million km/hour.

This is so fast that the star has a rather strange shape.

We call these objects pulsars, because they emit a strong radio signal.

And the magnetic field of a neutron star is roughly 8 trillion times stronger than the magnetic field of Earth.

So strong that atoms get bent when they enter it's influence.

Okay, I think we got the point across.

Neutron stars are some of the most extreme, but also some of the coolest objects in the universe.

Hopefully, we will one day send spaceships to learn more about them, and take some neat pictures!

But we shouldn't get too close!

Subtitles by: Mohammed Abdulhak (m_abdulhak@outlook.com)