Inhabitability of our world several timesendangered by large-scale extinction, however, the Earth’s magnetic field saved the lives of its inhabitants at two key points in the history of the blue planet. Thanks to the creation of a powerful protective field around the planet in the early stages of its formation, the components necessary for the emergence of life could successfully survive several powerful solar bursts. What can this discovery mean for science, and how can it help in the search for potentially inhabited exoplanets?
Life on Earth was several times in danger of mass extinction
Our sun is far from the calmest star inThe universe. Every second it releases a huge amount of harmful charged particles - the solar wind. It is believed that in the distant past, Mars had its own magnetic field, which at some point was lost. After the red planet lost its natural defense, the charged particles gradually deprived Mars of its atmosphere and oceans, newsweek.com reports.
In a study published in a scientific journalPNAS, the researchers studied the Earth’s early magnetic field, which appeared very successfully right after the planet formed 4.5 billion years ago. Until recently, it was believed that a magnetic field formed about 3.5 billion years ago, but in 2015, researchers led by John Tarduno, a professor of geophysics at the University of Rochester, found evidence that the magnetic field is at least 4.2 billion years old. years.
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At the beginning of earthly history, our planet accounted forfight powerful solar winds coming from a young and very hot-tempered sun. When interacting with the unprotected atmosphere of the Earth, the winds could completely deprive the planet of water, making it look like Mars. Instead, the planet’s magnetic field was able to provide protection from charged solar particles, preventing atmospheric erosion and massive water losses.
Analysis of zircon crystals, which are one ofThe most ancient materials on the planet showed that the Earth's early magnetic field was stronger than it is now. Due to the fact that zircons have the width of a human hair, the study of the material requires special equipment, however, a number of experiments with crystals showed the reality of the existence of the Earth’s magnetic field 4.1 billion years ago.
It is believed that at this time the field was createdchemical reactions inside the planet, gradually cooling after formation. This is different from the way that a magnetic field is generated now, which is known to move in a liquid iron core.
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When chemical reactions in the core of the planetfinally stopped, the newly formed liquid core prevailed, the researchers believe. Scientists believe that the magnetic field retained planetary habitability in two periods important for life on Earth: in Hadei and in Ediacar about 565 million years ago, when the magnetic field almost completely collapsed immediately before the start of growth of the inner core. This discovery is of great value in the search for alien life on potentially inhabited exoplanets outside the solar system, because even the presence of water and the atmosphere in the early stages of planet formation does not guarantee the existence of life on the planet in the absence of a magnetic field. Thus, the magnetic field can be considered as a key component of planetary habitability, significantly narrowing the list of planets already discovered by astronomers with Earth-like characteristics.