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Which of the four terrestrial planets has the strongest magnetic area, Mars, Mercury, Venus, or Earth?
The Earth, by far.
The 4 huge planets have actually fairly solid magnetic areas. Amongst the terrestrial planets, just the Earth has a moderately strong magnetic area, yet weaker than those of the large planets. Mercury, prefer the Earth, has a self-sustained dipole magnetic area, however a lot weaker than that of the Planet. The Moon, and maybe Mars, appear to have had actually prehistoric planetary dynamos, yet not anyeven more. Finally, Venus also does not have actually a self-sustained dipole magnetic area.
One prior explanation for why the Moon and Mars perform not have actually self-sustained dipole magnetic areas has actually fallen by the wayside. It was lengthy posited that the cores of the Moon and also Mars have lengthy since frozen. This is not the instance. Analyses of the gravity fields of the Moon and also Mars have presented that those 2 objects have partially molten cores consisting of iron and also various other elements, just favor the Planet.
It shows up that three vital ingredients are needed for a terrestrial earth to have actually a far-ranging magnetic field:A molten or partly molten core consisting of iron, nickel, and also other facets. All 4 terrestrial planets and the Moon pass this criterion.A sufficiently high rotation rate. What that sufficiently high is topic to dispute. One rotation per sidereal day is obviously sufficiently high. Mars has actually an extremely equivalent rotation rate however does not have actually a self-sustained dynamo.A sufficiently high warmth flux throughout the core-mantle boundary. This is the one element that distinguishes the Planet from the other four terrestrial objects. Mercury, the Moon, and also Mars have actually static lid tectonics: their surencounters are frozen. Venus appears to have actually alternated in between static lid tectonics (which is what it has now) and also too much volcanic tectonics (the many reliable method to cool a planet).The Planet is the only one of those 5 objects to have actually plate tectonics. While not as efficient as excessive volcanism via regard to cooling a earth, it supposedly is excellent enough to keep the warmth flux across the core-mantle boundary that is required to keep a self-sustaining dynamo.