# Earth's gravitational Field vs. Mars's and Venus [closed]

Why does Earth still have an active, Hot interior core, but Mars and Venus have none?

• How does the title relate to the question? – Dmitry Brant Dec 17 '17 at 19:48
• This question posits something that is false. Mars has a hot, partially molten core. Venus almost certainly does, too. What Venus and Mars don't have is plate tectonics. – David Hammen Dec 17 '17 at 20:09
• Not "Earth's gravitational Field", but rather, "Earth's Magnetic Field" relative to Mars and Venus. In other words, without a hot turbulent core, there can be no Magnetic Fields on these two planets. Do they have Magnetic Fields? If not, Why? – Douglas D. Beatenhead Dec 18 '17 at 15:35

The variations in a planet's gravitational field provide a means for inferring characteristics of the planet. In particular, both Venus' and Mars' $k_2$ tidal Love number are consistent with a planet with a partially molten core but inconsistent with a planet with a solid core. The cores of Venus and Mars most likely look a lot like ours: a molten outer core, possibly surrounding a solid inner core. We'll need to place seismometers all over the surface of those planets to determine if they have a solid inner core.