Link to newsround

One half of Mars could be warmer than the other say scientists

An illustration of Mars cut in half showing the inside of the hotter southern hemisphereNASA/Theophilus Britt Griswold

Scientists have found Mars' interior matches it's surface in that the two halves of the planet are very different from each other.

The northern hemisphere has low flat lands while the southern hemisphere is filled with huge mountains and craters.

New research from scientists has found that it's hundreds of degrees hotter under the surface of the Red Planet's southern hemisphere compared to the north.

It's another step in answering the age-old question of whether there has ever been life on Mars.

More on Mars

Illustration of Mars orbiter NASA

Scientists studied data from tech like Nasa's Mars Reconnaissance Orbiter

Mars can be quite cold on the surface, reaching highs of around 20C and lows of a chilly -153C.

But new research shows the southern hemisphere is about 200-400 degrees hotter than the northern half.

Scientists looked at information about the planet's gravitational field collected on three different Mars missions and used how these have varied over time to build a model of the planet's interior.

This new finding matches the diversity on the planet's surface where the northern and southern hemispheres look very different.

More research will need to be done to understand what created the difference in temperatures but researchers have some theories.

One theory suggests there was once some sort of giant impact in the north, releasing heat.

Another suggests thick geological features (like mountains) in the south stop excess heat from escaping.

An illustration of what scientists think the inside of Mars looks like. There is a yellow core. The southern hemisphere is a lighter red showing it's hotter while the northern hemisphere is darker red showing it's colder Berne et al./Nature.

Alexander Berne from the University of Arizona said;

"Scientists usually assume that the interiors of planetary bodies are generally spherically symmetric (the same on each half of the planet), but this is not necessarily true."

"As we get more gravity data, we can determine the three-dimensional intricacies of a planet's interior structure.

"These inferences in turn give us a blueprint for designing future missions and scientific exploration of these worlds.

"Understanding the interior structure of planetary bodies helps us unravel the processes that shaped their formation and evolution."