The magnetic field of the Earth is significantly older than researchers believed, according to a new study. This investigation concludes that this powerful field, which protects the surface of our world from dangerous levels of radiation, developed soon after our globe coalesced from a primordial gas.
Geologists and physicists had previously estimated that the magnetic field of the Earth formed 3.45 billion years before our time. One of the researchers of that previous study has now presented new evidence pushing that date back significantly in the geological record. According to the new research, the magnetic field of the Earth has been around for more than four billion years.
Researchers examine magnetic crystals held inside ancient rocks in order to determine how the magnetic field of the Earth developed over time. In order to search for evidence of the field from far back in time, investigators headed to Western Australia, where four-billion-year-old zircon crystals are found in the Jack Hills region. Tiny crystals containing iron were examined using a high-resolution magnetometer, revealing information about the magnetic field of our planet over time.
Investigators found good evidence of a planetary magnetic field four billion years ago, and less convincing evidence of a field 200 million years before that ancient epoch.
This study could help geologists and other researchers better understand how the Earth formed.
"There's this tremendous record between 3.5 billion and 4.2 billion [years] that we really need to explore," John Tarduno from the University of Rochester said.
If this finding is confirmed by other experiments, it could explain how life evolved so quickly on our planet. An early development of a magnetic field would have provided a planetary shield, protecting early life. Such a field would have also prevented the solar wind, emanating from the sun, from stripping away the atmosphere of the early Earth.
Mars also possessed a magnetic field four billion years ago, but most of its atmosphere was stripped away over the course of eons. Meanwhile, life thrived over the entire globe here on Earth.
"The comparison between Earth and Mars is really striking," Tarduno told reporters.
Although most researchers believe a magnetic field is necessary around a planet in order for life to thrive, some theories of alien life suggest bizarre forms of life may actually thrive on energy absorbed from solar wind.
The oldest known rocks in the world date back to roughly 4.4 billion years ago, but the magnetic field records in these samples is complex and confusing.
Analysis of the age of the Earth's magnetic field was profiled in the journal Science.