You are watching: Why does earth have the strongest magnetic field among the terrestrial worlds
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Which the the four terrestrial planets has actually the strongest magnetic field, Mars, Mercury, Venus, or Earth?
The Earth, through far.
The 4 giant planets have actually rather strong magnetic fields. Among the terrestrial planets, only the planet has a moderately strong magnetic field, yet weaker 보다 those of the large planets. Mercury, choose the Earth, has a self-sustained dipole magnetic field, however much weaker 보다 that that the Earth. The Moon, and also possibly Mars, show up to have actually had old planetary dynamos, but not anymore. Finally, Venus additionally does not have actually a self-sustained dipole magnetic field.
One prior explanation because that why the Moon and Mars do not have self-sustained dipole magnetic areas has please by the wayside. That was long posited that the cores that the Moon and also Mars have long due to the fact that frozen. This is no the case. Analyses that the gravity fields of the Moon and Mars have displayed that those 2 objects have actually partially molten cores consisting of iron and also other elements, just like the Earth.
It shows up that three crucial ingredients are required for a terrestrial world to have a significant magnetic field:A molten or partially molten core consisting of iron, nickel, and also other elements. All four terrestrial planets and the Moon pass this criterion.A sufficiently high rotation rate. What that sufficiently high is topic to debate. One rotation per sidereal day is obviously saturated high. Mars has actually a very similar rotation rate but does not have actually a self-sustained dynamo.A saturated high warmth flux across the core-mantle boundary. This is the one element that distinguishes the planet from the other four terrestrial objects. Mercury, the Moon, and Mars have static lid tectonics: your surfaces are frozen. Venus appears to have alternated between static lid tectonics (which is what it has now) and also extreme volcanic tectonics (the many efficient way to cool a planet).The planet is the only among those five objects to have plate tectonics. While not as reliable as excessive volcanism with regard to cooling a planet, it apparently is good enough to preserve the warmth flux across the core-mantle boundary that is required to keep a self-sustaining dynamo.