Mercury’s magnetic field oldest in our solar system, NASA Messenger reveals

Mercury's magnetic field might be 3.8 billion years old

NASA’s Messenger probe that crashed into Mercury after running out of fuel has detected magnetized rocks on the planet that suggest presence of magnetic field on the innermost planet of our solar system. Scientists believe that magnetic field on the planet might be more than 3.8 billion years old.

Messenger spacecraft which was sent on a four year mission to explore Mercury ended its venture last week and the probe was ordered to leave the planet but it ran out of fuel and crashed into the planet. However, before crashing it gave tons of information including several amazing close-up images and more sophisticated data about the closest planet to Sun that will give a new insight in understanding our solar system. While flying 10 km above the Mercury surface it found traces of ancient magnetized rocks. However, the signal strength was very weak, that might also be a reason that such a field wasn’t recorded earlier.


With the finding, Mercury became the second planet in our solar system to boast magnetic field, earth is the only other planet that has its own global magnetic field. However, scientists believe that Mars also had its own magnetic field nearly 3 billion years ago, but somehow it lost the field. According to scientists, magnetic field is generated by a dynamo — motions of metallic fluids in the core.

According the data sent by the messenger, Mercury has very odd magnetized regions that might be nearly 4 billion years old. However, scientists aren’t sure whether the field has been constant since then or it has suffered some long pauses before it resumed again.

“The simplest possible explanation is that you switched a magnetic field on and then it just continued to the present day … but it may turn out that it would have been easier for that field to have switched on and off,” said MESSENGER guest investigator Catherine Johnson, a geophysicist with the University of British Columbia in Vancouver.

In addition, data also suggests that Mercury had developed global magnetic field soon after its formation, nearly 700 million years after its formation. This information will spew come clues on when and how the planet develops liquid iron core.

The research will be published this week in the journal Science.

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