According to new data from NASA's Messenger spacecraft, Mercury's magnetic field was formed some 4 billion years ago. This unusual finding was also the last new findings of the probe that outlasted its planned lifeplan.

Messenger (MErcury Surface, Space ENvironment, GEochemistry and Ranging) spacecraft was launched towards the tiny planet in August 2004, where it arrived seven years later. The probe observed Mercury for four years which is three years longer than the planned one year mission.

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Earth also has a magnetic field but Mercury's field is much weaker than our planet's. Scienists believe that this phenomenon is caused by the moving liquid iron core inside Mercury which is also similar with the process that happens inside Earth.

Mercury formed around 4.4 billion years ago along with the rest of the solar system. Data on the Messenger probe is suggesting that the magnetic field on the scorching world first formed between 3.7 to 3.9 billion years ago.

The feature was detected by the magnetometer aboard the probe along with its suite of scientific instruments when it arrived closer to the surface in late 2014 and early 2015. This magnetism was found in rocks and soil as it was too weak to detect in high orbit.

According to Catherine Johnson who is a planetary scientist from the University of British Columbia, this mission is orignally planned to last one year but nobody expected that it would go further into four years. The science from these recent data is really interesting and the magnetic field of Mercury is just the first discovery.

Apparently Venus nor Mars has a magnetic field although prior studies suggest that Mars possessed one some 3 billion years ago.

Johnson adds that magnetized rocks hold clues about the magnetic field of the planet which is pivotal in understanding its evolution. Mercury was volcanically and tectonically active 3.7 to 3.9 years ago and now, we know that it has a magnetic field during that time. 

Messenger is the second spacecraft to orbit Mercury following Mariner 10 that flew by in 1973. The probe completed 4,000 orbits around Mercury before it crashed on the surface on April 30, 2015. 

This study is published in the journal Science. 

TagsNASA, NASA MESSENGER, NASA Messenger spacecraft, mercury planet, magnetic field Mercury, messenger magnetic filed mercury, messenger magnetic field mercury, magnetic field planets