All the planets of the Solar system have very hot cores. The cores of the inner planets Mercury, Venus, and Earth are composed of iron-nickel. Mars's core is made of solid iron sulfide mixed with some nickel. The cores of all 4 outer planets are made of some combination of rock, metal and hydrogen compounds. read more
All the planets of the Solar system have very hot cores. The cores of the inner planets Mercury, Venus, and Earth are composed of iron-nickel. Mars's core is made of solid iron sulfide mixed with some nickel. The cores of all 4 outer planets are made of some combination of rock, metal and hydrogen compounds. read more
The planetary core consists of the innermost layer(s) of a planet; which may be composed of solid and liquid layers. Cores of specific planets may be entirely solid or entirely liquid. In the Solar System, core size can range from about 20% to 85% of a planet's radius . read more
Depends on what you call"planet." For example, in comparison to Earth, the Earth and Moon is a"binary planet system." And the moon doesn't have any molten core. Also, you said inner. Inner core of Earth (and many other planets) are solid because of (what I think is pressure). read more