Geodynamo, solar wind, and magnetopause 3.4 to 3.45 billion years ago

John A. Tarduno, Rory D. Cottrell, Michael K. Watkeys, Axel Hofmann, Pavel V. Doubrovine, Eric E. Mamajek, Dunji Liu, David G. Sibeck, Levi P. Neukirch, Yoichi Usui

Research output: Contribution to journalArticlepeer-review

249 Citations (Scopus)

Abstract

Stellar wind standoff by a planetary magnetic field prevents atmospheric erosion and water loss. Although the early Earth retained its water and atmosphere, and thus evolved as a habitable planet, little is known about Earth's magnetic field strength during that time. We report paleointensity results from single silicate crystals bearing magnetic inclusions that record a geodynamo 3.4 to 3.45 billion years ago. The measured field strength is -50 to 70% that of the present-day field. When combined with a greater Paleoarchean solar wind pressure, the paleofield strength data suggest steady-state magnetopause standoff distances of ≤5 Earth radii, similar to values observed during recent coronal mass ejection events. The data also suggest lower-latitude aurora and increases in polar cap area, as well as heating, expansion, and volatile loss from the exosphere that would have affected long-term atmospheric composition.

Original languageEnglish
Pages (from-to)1238-1240
Number of pages3
JournalScience
Volume327
Issue number5970
DOIs
Publication statusPublished - 5 Mar 2010
Externally publishedYes

ASJC Scopus subject areas

  • Multidisciplinary

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