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A new study shows the moon’s magnetic field lasted at least a billion years longer than thought. That suggests other moons may be able to shelter life. The moon's magnetic field lasted at least 1 billion years longer than previously thought, a new study finds. This suggests that alien moons and planets may also have magnetic fields that can survive for a long time and potentially help shelter extraterrestrial life. The moon today does not possess a global magnetic field. However, prior analyses of moon rocks retrieved by the Apollo astronauts suggested that, between 3.56 billion and 4.25 billion years ago, the moon's magnetic field once ranged in strength from 20 to 110 microtesla. In comparison, Earth's magnetic field is 50 microtesla strong. Previous research also suggested that the moon's magnetic field had declined in intensity to less than 4 microtesla by 3.19 billion years ago. However, researchers weren't sure what happened after that point — whether it died out shortly thereafter or lingered in a weakened state before dissipating completely. Understanding more about the nature of the magnetic field of Earth's moon could shed light on the magnetic fields of distant moons and planets, which could influence their habitability, according to the researchers who conducted the new study. Earth's magnetic field protects its oceans and its life from dangerous radiation from the sun; the death of Mars' magnetic field could help explain why the Red Planet is now dry and apparently lifeless. "Magnetic fields can shield planets from stellar winds which can strip atmospheres of water, which is important for planetary habitability," study lead author Sonia Tikoo, a lunar geophysicist at Rutgers University in New Brunswick, New Jersey, told Space.com.