The Mercury planet has a solid inner core of the same size as the Earth

A new analysis has shown that mercury has a strong inner core, just like the Earth. And the core of Mercury is about the same size as our own planet.

I am biased, but Mercury is an incredible and mysterious planet that continues to offer interesting results to scientists. Perhaps the most intriguing, it generates its own magnetic field from motion within the planet, just like the Earth. The discovery of Mercury's solid inner core could help scientists better understand both planets.

"A better understanding of the size of the solid inner core provides crucial information about the history of the planet's interior and, therefore, its magnetic field," said Antonio Genova, assistant professor at the Sapienza Università di Roma and first author of the study. Gizmodo in an email. "The solidification of the nucleus also plays a major role in the evolution of the earth's internal and terrestrial magnetic field."

The most recent spacecraft to have studied the planet closely is NASA's MESSENGER (Surface, Environment, Geochemistry and Telemetry) mission launched in 2004 and piloted by the Mercury from 2011 to 2015. During this mission, she took detailed measurements of the planet's surface, its gravitational field, and its rotation, hoping scientists would find out what Mercury looked like inside. Recently, scientists conducted a new analysis of the probe's Radio Science instrument, taking into account a new technique for accurately determining the planet's orbit.

This has led to new estimates of the gravitational field of the planet, according to the article recently published in Geophysical Research Letters. These results demonstrate that the planet has a solid inner core that accounts for about 30 to 70% of the total radius of the Mercury nucleus.

"Mercury is now the second rocky planet – after Earth – for which we have evidence of a strong internal core," said Sean Solomon, the lead investigator of the MESSENGER mission, in Gizmodo.

It's not an exact value, but the mere presence of a solid inner core says something important – it helps scientists better understand how the planet generates its magnetic field. On Earth, scientists attribute our own magnetic field to the dynamo, the heat of the inner core combined with the rotational motion of the planet driving the metal into the outer liquid core. The interior of the Mercury is also cooling down, as evidenced by the landforms generated by its surface contractions. The size of the solid inner core will help scientists better understand this cooling, said Solomon.

But think of the planet in relation to ours: if the solid nucleus occupied half of the radius of Mercury, it is about 1000 kilometers, according to the calculations of the newspaper, more than 40% of the total radius of the planet is lower than 2,500 kilometers. The Earth's solid core, on the other hand, is about 1,200 kilometers long, which is less than one-fifth of the total 6,370-kilometer radius of our planet. Scientists question the reasons for these differences.

Fortunately, another mission to the rocky interior planet called BepiColombo. Hopefully scientists will soon solve some mysteries of Mercury.