Privileged Planet: magnetic field history findings (Introduction)

by David Turell , Tuesday, July 26, 2022, 17:26 (852 days ago) @ David Turell

We would not be here without it:

https://phys.org/news/2022-07-earth-mars-like-fate-ancient-clues.html

"Approximately 1,800 miles beneath our feet, swirling liquid iron in the Earth's outer core generates our planet's protective magnetic field. This magnetic field is invisible but is vital for life on Earth's surface because it shields the planet from solar wind—streams of radiation from the sun.

"About 565 million years ago, however, the magnetic field's strength decreased to 10 percent of its strength today. Then, mysteriously, the field bounced back, regaining its strength just before the Cambrian explosion of multicellular life on Earth.

"What caused the magnetic field to bounce back?

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"Earth's magnetic field is generated in its outer core, where swirling liquid iron causes electric currents, driving a phenomenon called the geodynamo that produces the magnetic field.

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"550 million years ago: the time at which the magnetic field began to renew rapidly after a near collapse 15 million years before that. The researchers attribute the rapid renewal of the magnetic field to the formation of a solid inner core that recharged the molten outer core and restored the magnetic field's strength.

"450 million years ago: the time at which the growing inner core's structure changed, marking the boundary between the innermost and outermost inner core. These changes in the inner core coincide with changes around the same time in the structure of the overlying mantel, due to plate tectonics on the surface.

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"Researchers believe that Mars, for example, once had a magnetic field, but the field dissipated, leaving the planet vulnerable to solar wind and the surface without oceans. While it is unclear whether the absence of a magnetic field would have caused Earth to meet the same fate, "Earth certainly would've lost much more water if Earth's magnetic field had not been regenerated," Tarduno says. "The planet would be much drier and very different than the planet today."

"In terms of planetary evolution, then, the research emphasizes the importance of a magnetic shield and a mechanism to sustain it, he says.

"'This research really highlights the need to have something like a growing inner core that sustains a magnetic field over the entire lifetime—many billions of years—of a planet.'"

Comment: it is fascinating how carefully the magnetic field was developed. For early life deep in oceans, its lower levels were not a problem, but for land life it had to be protectively stronger. Only a designed plan could have produced this evolutionary scenario.