Tuesday, October 27, 2020
Home Tech & Gadget Why the moon’s early magnetic field might be responsible for life on...

Why the moon’s early magnetic field might be responsible for life on earth


The habitability of a planet depends on many factors. One is the existence of a strong and long-lasting magnetic field. These fields are generated thousands of miles below the planet’s surface in its liquid core and extend far into space – shielding the atmosphere from harmful solar radiation.

Without a strong magnetic field, a planet finds it difficult to cling to a breathing atmosphere – which is bad news for life as we know it. A new study, published in Science Advances, suggests that the Moon’s now extinct magnetic field may have helped protect our planet’s atmosphere as life formed around 4 billion years ago.

Today, the Earth has a powerful global magnetic field that shields the atmosphere and low-orbiting satellites from harsh solar radiation. In contrast, the Moon has neither a breathable atmosphere nor a global magnetic field.

Global magnetic fields are generated by the movement of molten iron in the cores of planets and moons. Keeping the fluid moving requires energy, such as heat trapped in the core. When there is not enough energy, the field dies.

Without a global magnetic field, the charged particles of the solar wind (solar radiation) passing near a planet generate electric fields that can accelerate charged atoms, called ions, out of the atmosphere. This process is happening on Mars today and it loses oxygen as a result – something that has been directly measured by Mars’ Atmosphere Mission and Volatile Evolution (Maven). The solar wind can also collide with the atmosphere and project molecules into space.

The Maven team estimates that the amount of oxygen lost from the Martian atmosphere during its history is equivalent to that contained in a global layer of water 23 meters thick.

[Read: The Moon’s surface is rusting — and Earth may be to blame]

Probe ancient magnetic fields

The new research examines how the first fields of the Earth and the Moon may have interacted. But probing these ancient fields is not easy. Scientists rely on ancient rocks that contain small grains that have been magnetized as the rocks formed, saving the direction and strength of the magnetic field at that time and place. These rocks are rare and extracting their magnetic signal requires careful and delicate laboratory measurements.