This is based on:
* Seismic data: Analysis of seismic waves generated by meteorite impacts provides information about the structure and composition of Mars' interior, including the core.
* Magnetic field data: The presence of a weak magnetic field suggests that the core is at least partially molten, implying high temperatures.
* Modeling: Mathematical models based on the planet's size, composition, and gravitational field are used to estimate the core temperature.
It's important to note that these are just estimates, and the actual core temperature could be different. More research and data are needed to refine our understanding of Mars' internal structure and temperatures.