MAGNETARS: THE MOST POWERFUL MAGNETS IN THE UNIVERSE

A 10-Year-Old's Guide to the Tiny Stars With Giant Magnetic Powers

Imagine taking something about the size of a city and giving it a magnetic field so powerful that it is among the strongest magnetic fields known anywhere in the universe.

Now imagine that this object is the crushed remains of a giant star.

It spins.

It flashes X-rays.

It can suddenly explode with enormous bursts of energy.

And its magnetic field can be trillions of times stronger than Earth's magnetic field.

This incredible object is called a magnetar.

Magnetars are some of the strangest things scientists have ever discovered.

They are not giant stars anymore. They are tiny, incredibly dense objects called neutron stars.

Scientists have identified about 30–31 magnetars, depending on which catalog and classification are being used. NASA materials describe 31 confirmed magnetars, while the McGill Online Magnetar Catalog has around 30 listed objects, including confirmed objects and candidates. So the number is much larger than the "11 or more" sometimes quoted in older material. (NASA Science)

But how can something so small be so powerful?

To understand that, we have to begin with a star.

1. Everything Begins With a Giant Star

Stars are enormous balls of extremely hot gas.

Our Sun is a star.

It looks huge from Earth, but compared with some stars, our Sun is actually fairly ordinary.

Some stars are many times more massive than the Sun.

Inside a star, enormous amounts of energy are being produced.

Gravity is constantly trying to pull the star inward.

At the same time, energy produced inside the star pushes outward.

For most of a star's life, these effects balance each other.

But eventually, a very massive star can run out of the fuel it needs to keep producing energy in the same way.

Then gravity takes over.

The center of the star collapses.

The outer part can explode in a gigantic event called a supernova.

And what is left behind can be something extraordinary.

A neutron star.

2. A Star Can Become Smaller Than a City

Here is one of the strangest facts about neutron stars:

A neutron star can contain more mass than the Sun while being only about the size of a city.

Think about that.

The Sun is about 1.4 million kilometers across.

A neutron star may be only around 20 kilometers across.

That means an enormous amount of matter has been squeezed into an incredibly small space.

It is difficult for our brains to imagine.

Imagine taking an entire mountain and squeezing it into something as small as a sugar cube.

That is closer to the kind of crazy density we are talking about.

Neutron stars are so dense because their original star has collapsed under gravity.

The atoms inside are crushed together.

Much of the matter becomes a sea of neutrons.

That is where the name neutron star comes from.

And sometimes, something even more extraordinary happens.

The neutron star becomes a magnetar.

3. What Makes a Magnetar Different?

All neutron stars have strong magnetic fields.

But magnetars have extraordinarily strong ones.

Think of Earth's magnetic field.

It is strong enough to help a compass point north.

Earth's magnetic field also helps protect our planet from some charged particles coming from the Sun.

Now imagine making a magnetic field vastly stronger.

Then stronger again.

Then stronger again.

Magnetars take magnetic power to an entirely different level.

NASA describes magnetar magnetic fields as roughly 10 trillion times stronger than a typical refrigerator magnet and about a trillion times stronger than the Sun's magnetic field. (NASA Science)

That is why the name is so appropriate:

MAGNET + STAR = MAGNETAR

It is basically a cosmic super-magnet.

4. But Why Is the Magnet So Powerful?

This is one of the great scientific questions.

Scientists think that when the original massive star collapses, its magnetic field can become enormously concentrated.

Think about spreading a small amount of paint over a large wall.

The paint is spread out.

Now imagine squeezing that same amount of paint onto a tiny piece of paper.

The paint becomes much more concentrated.

Something somewhat similar happens to magnetic fields during stellar collapse.

A huge star becomes a tiny neutron star.

The magnetic field becomes concentrated into a much smaller area.

But there is more to the story.

Scientists think that the movement of extremely hot, electrically conducting matter inside the newborn neutron star can help create and strengthen an enormous magnetic field.

This process is sometimes compared to a dynamo.

It is like a gigantic cosmic generator.

The details are still being studied.

And that is important.

Scientists understand many things about magnetars, but they do not yet have every answer about exactly how the strongest magnetic fields are created.

5. Magnetars Are Tiny but Incredibly Heavy

Let's compare a magnetar with Earth.

Earth is about 12,742 kilometers wide.

A magnetar might be only around 20 kilometers across.

So you could imagine a magnetar as something roughly the size of a city.

But its mass can be greater than the Sun's.

That means a teaspoon-sized amount of neutron-star material would be unbelievably heavy.

It is difficult to give a simple everyday comparison because nothing on Earth has the same density.

The important idea is this:

A magnetar is tiny in size but enormous in mass and energy.

It is like taking an entire mountain range and packing it into a small city.

6. Magnetars Spin

Magnetars also rotate.

Some rotate relatively slowly compared with many other neutron stars.

Typical magnetar spin periods are often measured in a few seconds.

That means the entire object can rotate once every few seconds.

Imagine a city-sized object with more mass than the Sun spinning over and over again.

That is astonishing.

As the magnetar rotates, its radiation can sweep through space.

If one of its beams points toward Earth at the right time, our telescopes may detect a pulse.

This is one reason magnetars are related to another fascinating type of neutron star:

pulsars.

7. What Is a Pulsar?

Imagine a lighthouse.

A lighthouse has a light that rotates.

For part of the rotation, the light points toward you.

Then it points away.

Then it comes back around.

If you are standing in the right place, you see:

FLASH... FLASH... FLASH... FLASH.

Some neutron stars behave in a similar way.

They can send beams of radiation through space as they rotate.

When those beams sweep across Earth, telescopes can detect regular pulses.

That is why these objects are called pulsars.

Some magnetars can behave like pulsars.

But magnetars have another major source of power:

Their magnetic fields.

8. Magnetars Can Have Starquakes

Here is where things become really exciting.

A magnetar has an incredibly strong magnetic field.

That magnetic field can twist and change.

The surface of a neutron star is also extremely unusual.

It has a solid crust.

As the magnetic field changes, it can place enormous stress on the crust.

Eventually, the crust can crack or shift.

Scientists call these events starquakes.

Imagine Earth having an earthquake.

Now imagine an earthquake happening on a tiny star with a magnetic field billions and billions of times stronger than anything we experience.

The energy released can be enormous.

That energy can produce powerful bursts of X-rays and gamma rays.

9. Magnetars Can Suddenly Explode With

Radiation

Most of the time, a magnetar may be relatively quiet.

Then suddenly:

BOOM!

It can release a burst of high-energy radiation.

Some bursts last less than a second.

Others can last much longer.

NASA explains that magnetar bursts can signal the failure of part of the star's crust under magnetic stress, beginning an active period that may last days to months. (HEASARC)

This is one reason magnetars can be difficult to discover.

They may remain quiet for years or decades.

Then suddenly become extremely active.

It is as if a sleeping cosmic monster suddenly wakes up and flashes brightly across the universe.

But remember:

A magnetar is not alive.

It is simply following the laws of physics.

10. The 1979 Mystery That Changed Astronomy

Magnetars became especially interesting because of a remarkable event in 1979.

Astronomers detected an enormous burst of gamma rays.

The event was unbelievably powerful.

It came from a source associated with the Large Magellanic Cloud, a small galaxy near our Milky Way.

At the time, scientists did not yet understand magnetars as well as they do today.

The discovery became one of the important clues that eventually led scientists toward the magnetar explanation.

NASA describes 1979 as an important starting point in the history of magnetar research. (Imagine the Universe)

Scientists began asking:

"What kind of object could possibly produce something this powerful?"

The answer turned out to be one of the strangest objects in the universe.

11. Scientists Started Finding More

For a long time, only a small number of magnetars were known.

Older NASA material sometimes said that only about a dozen had been discovered.

But astronomy improved.

New space telescopes became better at detecting X-rays and gamma rays.

Astronomers also became better at recognizing the strange behavior of neutron stars.

The number increased.

NASA reported that the discovery of J1818.0−1607 in 2020 brought the number of confirmed magnetars to 31. (NASA)

So if you see an older article saying there were only 10, 11, or 12 magnetars, don't assume scientists made a mistake.

That number was accurate for the time when the article was written.

Science changes as discoveries are made.

12. Meet Magnetar J1818.0−1607

One particularly interesting magnetar is called J1818.0−1607.

Don't worry about remembering the entire name.

Scientists give objects names like this because their names often describe their location in the sky.

J1818.0−1607 was discovered in March 2020.

NASA reported that it was only the 31st magnetar identified at that time.

It was also special because it appeared to be extremely young—possibly only around 500 years old based on estimates from its spin-down behavior and assumptions about how fast it was spinning when it formed. (NASA)

It also spins about once every 1.4 seconds.

Imagine a city-sized object with more mass than the Sun spinning once every second and a half.

That is an incredible cosmic machine.

13. Another Famous Magnetar: SGR 1935+2154

One of the most exciting magnetars is called SGR 1935+2154.

It became especially famous in 2020.

Scientists detected a powerful burst from it that included both X-rays and radio waves.

The radio burst looked like something called a fast radio burst, or FRB.

FRBs are incredibly short flashes of radio energy that can travel across enormous distances.

Scientists had been detecting FRBs from distant galaxies for years.

But the 2020 event gave scientists something very important:

Evidence that at least some FRBs can come from magnetars. (NASA Jet Propulsion Laboratory)

This was a major clue.

It was like finding a fingerprint at a mystery scene.

Scientists could now connect two previously mysterious phenomena.

14. What Is a Fast Radio Burst?

A fast radio burst is exactly what its name suggests.

It is a very fast burst of radio energy.

Some last only milliseconds.

A millisecond is one thousandth of a second.

Imagine snapping your fingers.

An FRB can happen much faster than you can blink.

And yet, despite being incredibly short, these bursts can release enormous amounts of energy.

The 2020 event from SGR 1935+2154 showed that magnetars can produce powerful radio bursts that resemble FRBs seen from other galaxies. (NASA Jet Propulsion Laboratory)

Scientists are still investigating exactly how all FRBs are produced.

But magnetars are now considered an important part of that mystery.

15. Magnetars Can Also Help Explain Gold

Here is something that may surprise you.

Scientists are investigating whether magnetars may have played a role in creating some of the heavy elements found in the universe.

Gold is one of the elements heavier than iron.

For a long time, scientists have wondered:

Where did all the gold come from?

Some heavy elements can be created in powerful cosmic events.

Magnetar activity may contribute to the creation and distribution of some heavy elements under certain conditions.

NASA reported in 2025 on research using old data to investigate whether magnetar-related events could help explain how gold and other heavy elements are produced. (NASA Science)

This does not mean that every piece of gold on Earth came from a magnetar.

It means magnetars may be part of the much bigger cosmic story of how the universe creates heavy elements.

16. Magnetars Are Like Natural Physics Laboratories

Scientists cannot build a magnetar in a laboratory.

We cannot create something with more mass than the Sun and squeeze it into a city-sized object.

Fortunately, the universe has already built these objects for us.

That makes magnetars natural laboratories.

Scientists can study them to learn about:

• extreme gravity

• powerful magnetic fields

• nuclear matter

• X-rays

• gamma rays

• radio waves

• star formation

• stellar explosions

• the behavior of matter under extreme pressure

A magnetar allows scientists to test ideas that would be impossible to test on Earth.

17. The Magnetic Field Is Almost Impossible to Imagine

Let's return to the magnet.

A refrigerator magnet can hold a note to your refrigerator.

Earth's magnetic field helps guide compasses.

A magnetar takes the idea of magnetism to an almost unimaginable level.

NASA has described magnetar magnetic fields as around 10 trillion times stronger than a refrigerator magnet. (NASA Science)

This is why scientists sometimes describe magnetars as the strongest magnets known in nature.

But there is an important warning:

Don't imagine that a magnetar is like a giant refrigerator magnet floating in space.

Its magnetic field is produced by completely different physics.

And because it is so far away, its magnetic field is not pulling objects around Earth.

18. Would a Magnetar Destroy Earth?

If a magnetar were extremely close to Earth, it could be dangerous.

But known magnetars are enormously far away.

Space is huge.

The distance between stars is enormous.

So even though magnetars are incredibly powerful, that does not mean Earth is in danger from one.

This is another important lesson about astronomy:

Power and distance both matter.

The Sun is powerful, but we are far enough away that its energy gives Earth warmth instead of destroying us.

A magnetar is vastly more extreme in certain ways, but the known ones are very far away.

19. Why Are There So Few Magnetars?

Scientists know thousands of neutron stars, but only around 30–31 objects are identified as magnetars in the commonly cited catalogs. NASA materials likewise describe 31 confirmed magnetars. (NASA Science)

Why so few?

There may actually be many more.

We may simply not see them.

Remember that magnetars can become quiet.

If a magnetar is not producing a strong burst and is far away, it can be difficult to detect.

Scientists also think magnetars may not remain extremely magnetic forever.

Their magnetic fields can change and weaken over time.

That means some objects that were once very active magnetars may eventually become much quieter.

20. Magnetars Don't Live Forever

The universe is constantly changing.

Stars are born.

Stars live.

Stars die.

Neutron stars can change.

Magnetars can also change.

Their magnetic fields can lose energy.

Their bursts can become less frequent.

Eventually, a magnetar may become much quieter.

Scientists are trying to understand this entire life cycle.

One fascinating possibility is that magnetars may represent one stage in the life of certain neutron stars.

Imagine a star being born as a massive, energetic object.

It explodes.

Its center collapses.

A neutron star forms.

The newborn neutron star may have an enormous magnetic field.

It becomes a magnetar.

Over thousands of years, its behavior changes.

Eventually, its magnetic activity may decrease.

It becomes part of the quieter population of neutron stars.

21. Magnetars Are Not Black Holes

This is worth remembering because black holes and magnetars are both extreme objects.

A black hole is a region of spacetime where gravity is so strong that, after crossing the event horizon, nothing can escape.

A magnetar is a type of neutron star with an extraordinarily powerful magnetic field.

Both can form from the deaths of massive stars.

But they are very different.

A magnetar has a physical surface.

A black hole has an event horizon instead.

A magnetar can emit enormous amounts of radiation.

A black hole can have material and radiation around it, but light that crosses the event horizon cannot escape.

Both are fascinating.

But they are not the same thing.

22. The Universe Has Different Kinds of "Dead Stars"'

When we say a star "dies," it doesn't necessarily mean it disappears.

A star can leave behind different kinds of objects.

A smaller star like the Sun will eventually become a white dwarf.

A massive star can explode as a supernova and leave behind a neutron star.

If the remaining core is massive enough, it may form a black hole.

And some neutron stars can become magnetars.

So the death of a star can be the beginning of another incredible story.

The star is gone.

But its remains can continue affecting the universe for thousands, millions, or even billions of years.

23. What Is the Biggest Mystery About Magnetars?

Scientists still have many questions.

One major mystery is:

How exactly do magnetars create such enormous magnetic fields?

Scientists have good theories.

But there is still more to learn.

Another question is:

Why do some neutron stars become magnetars while others do not?

And another:

How exactly do magnetar bursts happen?

Scientists are also investigating how magnetars produce fast radio bursts.

They want to know whether magnetars are responsible for some, many, or perhaps most of certain types of FRBs.

They are also investigating how magnetars might contribute to the formation of heavy elements.

In other words, magnetars are not just objects we have discovered.

They are objects that create new questions.

24. Why Should a 10-Year-Old Care About Magnetars?

You might be thinking:

"Okay, magnetars are cool. But why does this matter to me?"

Because today's 10-year-olds are tomorrow's scientists, engineers, explorers, inventors, and thinkers.

A child who becomes fascinated by magnetars might someday study physics.

Another might become an astronomer.

Another might build space telescopes.

Another might invent a completely new way to study the universe.

Every scientific discovery begins with someone being curious.

And curiosity does not require you to know everything.

It requires you to ask:

"Why?"

25. The Most Amazing Part

Here is perhaps the strangest fact of all.

The atoms in your body were created by earlier generations of stars.

The carbon in your body.

The oxygen you breathe.

The calcium in your bones.

The iron in your blood.

Many of the elements around us were created by stars and cosmic events.

That means when you look at a magnetar, you are looking at another part of the same cosmic story that eventually produced Earth and life.

You are not separate from the universe.

You are made from the universe.

And magnetars are one of the universe's most extreme examples of what matter can become.

Conclusion: The Cosmic Super-Magnets

A magnetar is one of the most extraordinary objects known to science.

It begins with a massive star.

The star eventually runs out of fuel.

Its core collapses.

The outer layers can explode.

The remaining core becomes a neutron star.

And if the conditions are right, that neutron star can become a magnetar.

A tiny object, perhaps only around the size of a city, can contain more mass than the Sun.

It can rotate rapidly.

It can possess a magnetic field trillions of times stronger than Earth's.

Its crust can crack in starquakes.

It can release powerful X-rays and gamma rays.

It can produce bursts of radio energy.

One magnetar, SGR 1935+2154, even produced a radio burst that helped scientists understand the connection between magnetars and fast radio bursts. (NASA Jet Propulsion Laboratory)

And scientists continue to discover new clues.

As of the mid-2020s, the commonly cited number is around 30–31 known magnetars, rather than only 11. Different catalogs can differ because some objects are candidates or classifications can change as new evidence arrives. (Springer)

But perhaps the most important thing to remember is not the number.

Remember the idea:

A magnetar is a tiny piece of a dead star with an enormous magnetic personality.

It reminds us that size does not always determine power.

A magnetar can be smaller than a city but more massive than the Sun.

It can remain quiet for years and then suddenly release an enormous burst.

It can help us understand mysterious radio signals from distant galaxies.

It may even help us understand where some of the universe's heavy elements came from.

And it teaches us something bigger than astronomy:

The universe is full of things that sound impossible until we discover that they are real.

So the next time you look at the night sky, remember that the stars are not simply pretty lights.

Some are giant factories.

Some are dying.

Some leave behind neutron stars.

Some may become magnetars.

And somewhere, millions of light-years away, nature may be performing an experiment more powerful than anything humanity could ever build.

The universe is still full of mysteries.

And perhaps one day, a curious 10-year-old looking at the stars will become the scientist who discovers the next one.

Leonardo Mora

CEO of Vision

GAWK Corporation