You are watching: Why does earth have the strongest magnetic field among the terrestrial worlds?
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Which of the four terrestrial planets has the the strongest magnetic field, Mars, Mercury, Venus, or Earth?
The Earth, by far.
The four giant planets have rather solid magnetic fields. Among the terrestrial planets, just the earth has a moderately strong magnetic field, but weaker than those the the large planets. Mercury, like the Earth, has actually a self-sustained dipole magnetic field, however much weaker 보다 that that the Earth. The Moon, and also possibly Mars, appear to have had ancient 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 also Mars execute not have actually self-sustained dipole magnetic areas has collapse by the wayside. That was long posited the the cores that the Moon and Mars have long since frozen. This is not the case. Analyses that the gravity fields of the Moon and also Mars have shown that those two objects have actually partially molten cores consists of iron and also other elements, just like the Earth.
It shows up that three vital ingredients are required for a terrestrial world to have actually a far-ranging magnetic field:A molten or partially molten core consisting the iron, nickel, and also other elements. All 4 terrestrial planets and also the Moon happen this criterion.A saturated high rotation rate. What that sufficiently high is topic to debate. One rotation every sidereal work is obviously sufficiently high. Mars has a very comparable rotation rate yet does not have a self-sustained dynamo.A saturated high warmth flux throughout the core-mantle boundary. This is the one element that differentiate the planet from the other four terrestrial objects. Mercury, the Moon, and Mars have static lid tectonics: their surfaces room frozen. Venus shows up to have alternated between static lid tectonics (which is what it has now) and extreme volcanic tectonics (the most efficient way to cool a planet).The planet is the only among those five objects to have plate tectonics. While no as effective as extreme volcanism through regard come cooling a planet, it reportedly is great enough to preserve the warm flux throughout the core-mantle boundary the is essential to keep a self-sustaining dynamo.