But just think about the planet compared to our own: If the solid core took up half of Mercury’s core’s radius, that’s around 1,000 kilometers, according to calculations in the paper—over ...

They estimated that the solid, iron core is about 1,260 miles (2,000 kilometers) wide and makes up about half of Mercury's entire core (about 2,440 miles, or nearly 4,000 kilometers, wide).

They estimated that the solid, iron core is about 1,260 miles (2,000 kilometers) wide and makes up about half of Mercury's entire core (about 2,440 miles, or nearly 4,000 kilometers, wide).