You are watching: Why does earth have the strongest magnetic field among the terrestrial worlds?
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Which of the 4 terrestrial planets has the strongest magnetic area, Mars, Mercury, Venus, or Earth?
The Earth, by much.
The four gigantic planets have rather solid magnetic areas. Amongst the terrestrial planets, only the Earth has a moderately solid magnetic field, but weaker than those of the gigantic planets. Mercury, like the Earth, has a self-sustained dipole magnetic field, but a lot weaker than that of the Planet. The Moon, and maybe Mars, appear to have actually had primitive planetary dynamos, but not anymore. Finally, Venus also does not have actually a self-continual dipole magnetic field.
One prior explanation for why the Moon and Mars do not have actually self-continual dipole magnetic fields has fallen by the wayside. It was lengthy posited that the cores of the Moon and also Mars have actually lengthy considering that frozen. This is not the situation. Analyses of the gravity fields of the Moon and Mars have displayed that those two objects have actually partially molten cores consisting of iron and other elements, simply prefer the Earth.
It shows up that three crucial ingredients are needed for a terrestrial planet to have actually a far-reaching magnetic field:A molten or partially molten core consisting of iron, nickel, and various other aspects. All four terrestrial planets and the Moon pass this criterion.A sufficiently high rotation price. What that sufficiently high is topic to conflict. One rotation per sidegenuine day is obviously sufficiently high. Mars has actually a really comparable rotation price however does not have a self-sustained dynamo.A sufficiently high warmth flux across the core-mantle boundary. This is the one variable that distinguishes the Planet from the other four terrestrial objects. Mercury, the Moon, and also Mars have actually static lid tectonics: their surfaces are frozen. Venus appears to have actually alternated in between static lid tectonics (which is what it has now) and also excessive volcanic tectonics (the most efficient method to cool a planet).The Planet is the just one of those five objects to have plate tectonics. While not as efficient as too much volcanism through regard to cooling a planet, it reportedly is good enough to preserve the warmth flux throughout the core-mantle boundary that is needed to keep a self-sustaining dynamo.