How Big is Mercury?

Mercury is the smallest planet in the solar system with a radius of 1520 mi (2440 km). It is smaller than Mars, but bigger than our Moon. It is smaller than Jupiter's moon Ganymede and Saturn's moon Titan. It has the highest uncompressed density of all the planets 5300 kg m^-3. From this we know it has the largest fraction of metal. The metallic core is 42% of the volume of the planet. The Earth's core by comparison is 17% of the volume of the Earth. The core of Mercury is about the same size as the core of the planet Mars. Because of Mercury's high density, it has the same surface gravity as Mars, 3.7 m s^-2, even thought it is only ¹⁄₃ the size of Mars. Place the mouse on the planets to reveal their interiors.