Level 1 — Absolute Beginner
Scientists found something new about Mars. Mars is the red planet near Earth. Inside Mars, one side is hotter than the other side.
A new study came out on August 26, 2026. It says the rock deep inside Mars is not the same everywhere. The south side is much hotter than the north side. The hot rock may even be a little bit liquid.
A scientist named Alexander Berne led the study. He got his PhD from Caltech in 2026. Now he works at the University of Arizona.
Scientists used a special method called tidal tomography. It looks at tiny changes in Mars's shape. The Sun's pull on Mars causes these changes. This helps scientists see inside Mars without digging.
- planet
- A large round object in space that moves around a star, like Mars or Earth.
- interior
- The inside part of something, not the outside.
- rock
- The hard material that makes up the ground and the inside of a planet.
- hot
- Having a high temperature.
- liquid
- A substance that flows, like water, not solid and not gas.
- scientist
- A person who studies the world to learn new facts.
- study
- Careful research done to learn something new.
- shape
- The outer form of an object.
Level 2 — Elementary
Scientists have made a surprising discovery about Mars. For a long time, they believed the inside of Mars was shaped the same way all around. A new study now shows this is not true.
The study, published in the journal Nature on August 26, 2026, found that the mantle under Mars's southern highlands is much hotter than the mantle under the northern hemisphere. The difference is between 200 and 400 degrees Celsius. Some of this hot rock might even be partly molten, meaning it is partly liquid.
The research was led by Alexander Berne, who finished his PhD at Caltech in 2026 and now works as a postdoctoral researcher at the University of Arizona. His team used a technique called tidal tomography. This method studies tiny changes in the shape of Mars caused by the Sun's gravitational pull, which lets scientists map the temperature deep inside the planet without drilling into it.
This discovery could help explain several mysteries about Mars, including strange patterns of magnetism, unusual marsquake activity, and clues about the planet's ancient water. NASA's InSight lander had already found that seismic waves lose energy faster when they pass through the southern hemisphere than the northern one, and the new heat difference may explain why.
- mantle
- The thick layer of rock inside a planet, found under the crust.
- hemisphere
- One half of a planet, such as the northern or southern half.
- molten
- Melted, or partly turned into liquid, because of heat.
- gravitational
- Relating to the force that pulls objects toward each other, such as the Sun pulling on Mars.
- seismic
- Relating to waves that move through the ground, often caused by quakes.
- marsquake
- A shaking of the ground on Mars, similar to an earthquake on Earth.
- magnetism
- The invisible force that comes from a planet's magnetic field.
- postdoctoral researcher
- A scientist who does research after finishing a PhD degree.
Level 3 — Intermediate
For decades, planetary scientists assumed that the interior of Mars was roughly symmetrical, even as its surface told a different story: smooth, low plains blanket the northern hemisphere, while older, heavily cratered highlands dominate the south. A study published in the journal Nature on August 26, 2026, has now overturned that assumption, revealing that Mars's interior is fundamentally lopsided.
According to the research, the mantle beneath the southern highlands runs 200 to 400 degrees Celsius hotter than the mantle beneath the northern lowlands, and portions of it may be partially molten. The study was led by Alexander Berne, who completed his PhD at Caltech in 2026 and is now a postdoctoral researcher at the University of Arizona.
To reach this conclusion without drilling into the planet, Berne's team relied on a technique called tidal tomography, which analyzes minute deformations in Mars's shape produced by the Sun's gravitational pull. Because a hotter, softer mantle deforms differently than a cooler, stiffer one, these subtle shape changes act as a probe of temperature deep beneath the surface.
The finding offers a potential explanation for several long-standing Martian puzzles, including irregular patterns of magnetism, anomalous marsquake behavior, and lingering questions about the planet's ancient water history. It also fits with an earlier observation from NASA's InSight lander, which detected that seismic waves lose energy more quickly as they cross the southern hemisphere than when they cross the north, a discrepancy the newly mapped heat asymmetry may finally help explain.
- symmetrical
- Having matching parts on both sides, evenly balanced in shape or structure.
- mantle
- The thick layer of rock between a planet's crust and its core.
- molten
- Turned partly or fully to liquid by intense heat.
- tidal tomography
- A technique that maps a planet's interior by studying tiny shape changes caused by gravitational pull.
- deformation
- A small change in the shape of an object caused by an outside force.
- marsquake
- A quake, or shaking of the ground, that occurs on Mars.
- magnetism
- The force associated with a planet's magnetic field.
- postdoctoral
- Describing research work done by a scientist after earning a PhD.
Level 4 — Advanced
Mars has long presented planetary scientists with a puzzling dichotomy: a northern hemisphere smoothed by low plains set against a southern hemisphere armored in ancient, heavily cratered highlands, a contrast that has fueled decades of debate over its origin. A study published in the journal Nature on August 26, 2026, adds a striking new dimension to that debate by demonstrating that the asymmetry is not confined to the surface but extends deep into the planet's interior.
Led by Alexander Berne, who completed his PhD at Caltech in 2026 and now holds a postdoctoral position at the University of Arizona, the research team found that the mantle underlying the southern highlands runs 200 to 400 degrees Celsius hotter than its counterpart beneath the northern lowlands, and may be partially molten in places. Such a pronounced thermal contrast implies that Mars's interior evolved along divergent paths in its two hemispheres, a finding with implications for the planet's geological and magnetic history alike.
The team arrived at this conclusion through tidal tomography, a technique that exploits the minuscule deformations the Sun's gravitational pull induces in Mars's shape. Because warmer, softer mantle material responds differently to tidal forcing than cooler, more rigid rock, these deformations serve as a remote probe of subsurface temperature, allowing researchers to map thermal structure without the need for direct drilling.
The discovery carries explanatory weight well beyond thermodynamics. It may account for Mars's irregular magnetic field patterns, for anomalous marsquake behavior recorded across the planet, and for open questions surrounding its ancient water history. It also resonates with an earlier observation from NASA's InSight lander, which found that seismic waves attenuate more rapidly when traveling through the southern hemisphere than the northern one, an asymmetry that the newly identified thermal gradient may finally help explain.
- dichotomy
- A sharp division or contrast between two things.
- asymmetry
- A lack of balance or equivalence between two sides of something.
- mantle
- The layer of rock beneath a planet's crust and above its core.
- molten
- Melted by heat into a liquid or semi-liquid state.
- tidal tomography
- A method of mapping a planet's internal structure using tiny shape changes caused by gravitational tides.
- deformation
- A change in the shape or structure of an object caused by an external force.
- attenuate
- To become reduced in force, intensity, or energy, as a wave losing strength.
- marsquake
- A seismic event, or quake, that occurs on the planet Mars.
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