2010/03/04 by J. A. Tarduno, R. D. Cottrell, M. K. Watkeys +7 · 6 citations
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Geomagnetism and Paleomagnetism Studies #Solar and Space Plasma Dynamics #Astro and Planetary Science #Atmosphere (unit) #Earth's magnetic field #Magnetosphere #Mercury's magnetic field #Astrobiology #Billion years #Solar wind #Exosphere #Magnetopause #Geophysics #Geology #L-shell #Atmospheric sciences #Physics #Astronomy #Magnetic field #Meteorology #Ion
paper · doi:10.1126/science.1183445
openalex publication_date 2010/03/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23
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 approximately 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 < or = 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.