Stars with a much larger mass than our Sun
burn out after just a few million years;
in a gigantic explosion known as a supernova.
Moving at the speed of light,
millions of tons of plasma,
neutrinos and a whole lot of light are
ejected from this explosion.
But there's something left behind.
A neutron star is one of the
strangest things in our universe.
Its dimensions are pretty crazy but bear with us.
The star is only 20km (13 miles)across.
That's smaller than most cities!
Not only that but the sheer density of
this relatively tiny star is also bizarre.
A single cubic centimeter of a neutron
star weighs 400 million tons.
But what exactly does that mean?
To put it in perspective imagine
every single vehicle in the United States 
being crushed up into
just a single sugar cube.
Now imagine millions of those coming
together, and that's a neutron star.
With dimensions like this,
there would be some pretty
significant implications for us
if our Sun was suddenly replaced by one.
Let's get this straight.
Our Sun will never become a neutron star.
Why?
Because neutron stars are born from
suns that are 10-20 times the size of ours.
In 5 billion years, our Sun
will become a red giant
and then eventually a cold white
dwarf which is similar to a neutron star,
just much larger and much less dense.
But forget about all that,
this is WHAT IF after all.
So WHAT IF?
Well, a neutron star replacing our Sun
would be pretty dangerous, to say the least.
A neutron star's gravitational force would
be 2 billion times stronger than Earth's. 
This means that pretty quickly, every
single planet in our solar system
would be pulled towards
the star and be destroyed.
And it wouldn't stop there.
A neutron star rotates incredibly fast,
whereas our Sun
rotates once every 27 days or so.
A neutron star rotates
over 700 times every second!
This means the star would be whirling
throughout space at one-fifth of the speed of light.
After thousands of years, many
neutron stars begin to slow down and fizzle out.
But that doesn't always happen.
Sometimes a neutron star meets another star.
The neutron star will begin
to orbit the fully formed sun
and will start to feed off its atmosphere
until it eventually collapses in on itself
and becomes a black hole.
If you happened to be in
another galaxy at the time, 
you'd see the neutron star as a flashing
light, also known as a pulsar.
Discovered in 1967 by
astrophysicist Jocelyn Bell,
pulsars are caused by a
neutron star's magnetic field. 
Which, no surprise, is incredibly strong.
But let's hope this neutron
star isn't a magnetar.
What's a magnetar you ask?
It's an even stronger and
rarer type of neutron star.
A neutron star's magnetic
field may be incredibly strong, but,
a magnetar's magnetic field is
1,000 times more powerful.
Yeah, we weren't kidding about
these numbers being a little ridiculous.
The crust of this star is under
a massive amount of strain.
If it happens to move at all,
it creates a starquake.
Yes, this may be a super cool sounding
word but don't let that fool you.
These things are scary.
The crust of the star would
erupt in a massive explosion,
causing its magnetic field to react.
This would create a massive
solar storm that travels across the entire galaxy.
And it wouldn't just be any solar storm.
It would be trillions of times stronger
than anything the Sun could produce.
And what would happen if Earth
got hit by this massive solar storm?
Well, that sounds like a
question for another, WHAT IF.
