A solid metallic nucleus nearly as big as Earth could lurk deep in the smallest planet of the Solar System.
This emerges from new research based on data collected by NASA's NASA (Mercury Surface, Space Environment, Geochemistry and Ranging) ( MESSENGER ) mission. This spaceship orbited the tiny planet for four years before deliberately crashing on the surface of Mercury. Now scientists have used data from the end of the probe's mission to look at the planet deeper than ever before.
"Any new information about our solar system will help us to understand the larger universe," said Antonio Genova, lead author of the new research and assistant professor at the Sapienza University of Rome, said in a statement .
Related: Photos of Mercury by NASA's Messenger Spacecraft [1
These variations cause a spacecraft to only accelerate or slow down a hair, and are the result of patches of the planet that are more or less dense than the average. They were particularly detailed near the end of the spacecraft's mission when engineers sent the probe at a distance of up to 105 km above the surface of the planet.
By combining this information, scientists were able to create a detailed model. Then play with variables such as the size of a solid inner core and compare the results to reality. This modeling suggested that Mercury should have a solid inner core and that this nucleus should be quite large.
In fact, their most convincing model set had a solid inner core that had a diameter of 2,000 km. That's about half the size of Mercury's core, which makes up 85% of the planet. Even for terrestrial conditions it is huge. The solid inner core of the earth is about 2,400 km wide.
The research is described in a work published on March 15 in the journal Geophysical Research Letters .