Scientists May Have Finally Solved the Mystery of Strange Starquakes That Can Slow Down a Star

Space is full of strange and mysterious objects, but few are as fascinating as pulsars. These tiny, ultra-dense stars spin hundreds of times every second and send powerful beams of light and radio waves across space like giant cosmic lighthouses.

For many years, scientists believed they understood why these stars sometimes suddenly spin faster. But then astronomers discovered something completely unexpected—some pulsars suddenly slow down instead of speeding up.

This strange event is called an anti-glitch, and for years no one could explain how it happens.

Now, a new study by Long and his team suggests that the answer may lie in powerful magnetic starquakes. Their idea could explain both sudden speed-ups and slowdowns using the same process.

What Is a Pulsar?

A pulsar is the leftover core of a massive star that exploded in a supernova.

Although a pulsar is only about 20 kilometers (12 miles) wide, it contains more mass than our Sun. This makes it one of the densest objects in the universe.

Pulsars rotate extremely fast while sending beams of radiation from their magnetic poles. As the star spins, these beams sweep through space. If one of them points toward Earth, astronomers detect regular pulses, which is why these objects are called pulsars.

Most pulsars rotate with incredible accuracy, almost like perfect clocks. That is why even the tiniest change in their rotation can tell scientists something important about what is happening inside them.

What Is a Glitch?

Normally, a pulsar slowly loses energy and spins more slowly over time.

But sometimes something unusual happens.

The star suddenly spins just a little bit faster. This sudden increase in speed is called a glitch.

Scientists have known about glitches for more than 50 years.

The most popular explanation is called the starquake model.

Just as the Earth's crust can crack during an earthquake, the outer layer of a pulsar can also crack because of the enormous pressure inside the star.

When this happens, the star becomes slightly smaller. Since its size decreases a little, it spins faster, just like an ice skater spins faster by pulling their arms closer to their body.

This theory successfully explains many glitches seen in pulsars.

Then Scientists Found Something Even Stranger

Everything changed when astronomers observed an event that should not happen according to the old theory.

Instead of spinning faster, one pulsar suddenly slowed down.

Scientists called this event an anti-glitch.

The first confirmed anti-glitch was seen in a special type of pulsar called a magnetar.

Since then, astronomers have discovered more anti-glitches in other magnetars and even in some normal pulsars.

This created a big problem.

The old starquake theory could only explain stars spinning faster.

It could not explain how a star could suddenly lose speed.

Magnetars Have the Strongest Magnetic Fields in the Universe

Magnetars are among the most powerful objects ever discovered.

Their magnetic fields are incredibly strong—trillions of times stronger than Earth's magnetic field.

These magnetic fields are so powerful that they can affect the shape of the entire star.

This gave scientists a new idea.

Maybe gravity is not the only force causing starquakes.

Maybe the star's enormous magnetic field is also playing an important role.

A New Idea: Magnetic Starquakes

Long and his team believe that magnetic forces inside a pulsar slowly build up stress over time.

The powerful magnetic field bends and stretches parts of the star.

Eventually, the stress becomes too great.

The star suddenly cracks, creating a magnetism-driven starquake.

This is similar to an earthquake on Earth, except the force causing the crack is mainly magnetism instead of gravity.

According to the researchers, these magnetic starquakes can change the star's shape in different ways.

Sometimes the star becomes slightly smaller.

Sometimes it becomes slightly larger in certain regions.

This changes something called the moment of inertia, which determines how easily an object rotates.

One Theory Can Explain Both Events

The exciting part of this new idea is that it can explain both glitches and anti-glitches.

If the starquake makes the moment of inertia smaller, the star spins faster.

This produces a normal glitch.

If the starquake increases the moment of inertia, the star spins more slowly.

This produces an anti-glitch.

Unlike the old theory, this new model naturally explains both kinds of events without needing two completely different explanations.

Could Strangeon Stars Be the Answer?

The researchers also discuss another interesting possibility.

What if some pulsars are not neutron stars at all?

Instead, they could be something called strangeon stars.

Scientists believe neutron stars have only a thin solid crust while most of the inside is made of super-dense fluid.

Because only the crust is solid, only a small part of the star can crack during a starquake.

This limits how large a glitch can become.

Strangeon stars are different.

According to this idea, the entire star is solid from the surface to the center.

That means much more of the star can store stress before breaking.

When a starquake finally happens, it could release much more energy.

This could produce much larger glitches and anti-glitches than ordinary neutron stars.

Although strangeon stars have not yet been confirmed, they remain an exciting possibility.

The Stronger the Magnetic Field, the Bigger the Starquake

The researchers also found a simple connection between the strength of a star's magnetic field and the size of a glitch or anti-glitch.

Their calculations suggest that stars with stronger magnetic fields should produce larger changes in their rotation.

When they compared this prediction with observations, the results matched surprisingly well.

This does not prove the theory is correct, but it gives scientists confidence that they are moving in the right direction.

Future Observations Will Test the Theory

One of the best things about this idea is that it can be tested.

As astronomers discover more glitches and anti-glitches, they can compare the size of these events with the strength of each star's magnetic field.

If stronger magnetic fields consistently produce bigger glitches or anti-glitches, it would strongly support this new theory.

If not, scientists will need to rethink their ideas.

Why This Research Matters

This study is about much more than just strange starquakes.

It may help scientists understand what pulsars are actually made of and how matter behaves under the most extreme conditions in the universe.

If future observations confirm this theory, magnetic starquakes could become the missing piece that explains one of astronomy's biggest mysteries.

The research could also help answer an even bigger question: Are all pulsars neutron stars, or could some of them actually be strangeon stars?

As more powerful telescopes begin studying these incredible objects, we may finally discover the true nature of some of the universe's most mysterious stars.

Reference: Hanyuan Long, Ruipeng Lu, Weiyang Wang, Shunshun Cao, Hao Tong, Han Yue, Renxin Xu, "Pulsar anti-glitches: starquakes driven by magnetism?", RAA, 2026. https://arxiv.org/abs/2607.12285

Technical Terms 

Pulsar	A pulsar is the leftover core of a massive star after it explodes. It is extremely small, very dense, and spins very fast while sending beams of light and radio waves into space.
Magnetar	A magnetar is a special type of pulsar that has the strongest magnetic field known in the universe—trillions of times stronger than Earth's magnetic field.
Glitch	A glitch is when a pulsar suddenly spins a little faster than normal.
Anti-glitch	An anti-glitch is the opposite of a glitch. It happens when a pulsar suddenly spins a little slower.
Starquake	A starquake is like an earthquake, but instead of happening on Earth, it happens on the surface or inside a compact star when too much stress builds up and the star cracks.
Magnetism-driven Starquake	A starquake caused mainly by powerful magnetic forces inside the star instead of gravity.
Gravity-driven Starquake	A starquake caused mainly by the star's own immense gravity squeezing it until its crust cracks.
Magnetic Stress	The force created by a very strong magnetic field that pushes, pulls, or bends the material inside the star.
Elastic Deformation	When the star's material bends or changes shape because of stress without breaking immediately.
Breaking Threshold	The maximum amount of stress the star's material can handle before it finally cracks.
Moment of Inertia	A measure of how difficult it is for an object to rotate. If it becomes smaller, the star spins faster. If it becomes larger, the star spins slower.
Rotational Frequency	The number of times a star rotates every second.
Compact Object	An extremely dense object formed after a star dies, such as a neutron star, magnetar, or black hole.
Neutron Star	A compact star made mostly of tightly packed neutrons, formed after a massive star explodes.
Strangeon Star	A theoretical type of compact star that may be solid all the way through instead of having only a solid crust like a neutron star. Scientists are still investigating whether these stars exist.
Strong Matter	Matter held together by the strong nuclear force, such as the material inside atomic nuclei or possibly inside strangeon stars.
Ordinary (Electric) Matter	The matter we see every day, including people, planets, air, and stars like the Sun. It is made of atoms held together by electromagnetic forces.
Atomic Nucleus	The tiny central part of an atom that contains protons and neutrons. Almost all of an atom's mass is concentrated here.
Strong Nuclear Force	One of the four fundamental forces of nature. It is the force that holds protons and neutrons together inside an atomic nucleus. It is the strongest force over very short distances.
Equation of State	A scientific model that describes how matter behaves under different temperatures, pressures, and densities, especially inside neutron stars.
Quantum Chromodynamics (QCD)	The branch of physics that explains how quarks and gluons interact through the strong nuclear force to form particles like protons and neutrons.
Supra-nuclear Matter	Matter compressed to densities even greater than the material inside an atomic nucleus. It exists only inside objects like neutron stars.
Magnetic Reynolds Number	A number that tells scientists how well magnetic fields remain trapped inside a moving, electrically conducting material. A high value means the magnetic field stays inside the star for a long time.
Dynamo Action	A natural process in which the movement of electrically conducting material inside a star generates or strengthens magnetic fields.
Crust	The hard outer layer of a neutron star. It is the part that usually cracks during a starquake.
Elastic Stress	Internal force that builds up inside a solid object when it is squeezed, stretched, or bent.
Superfluid Vortex Model	Another theory for glitches. It suggests that a frictionless liquid called a superfluid inside neutron stars suddenly transfers its rotation to the crust, making the star spin faster.
Multipolar Magnetic Field	A complex magnetic field with many north and south magnetic poles, unlike Earth's simpler magnetic field that has mainly one north and one south pole.
Observable Prediction	A prediction that scientists can test using future observations or experiments. If the observations match the prediction, the theory becomes stronger.
Falsifiable Theory	A scientific theory that can be proven wrong if future observations do not support it. This is an important feature of good scientific theories.