The video explores Mercury's internal structure, focusing on its solid iron core. Historically, there were only hints of this core, but recent data from the MESSENGER spacecraft, which orbited Mercury from 2011, has provided more concrete evidence. Scientists used radio observations to determine Mercury's rotational pole and gravitational anomalies, helping them understand its orientation. By analyzing variations in the data, they confirmed that Mercury has a solid iron core, which constitutes about half of its entire core and is approximately 12,160 miles wide. This core makes up nearly 85% of Mercury's volume, leading scientists to compare the planet to a cannonball.

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