Notice a weird magnetic pulse? You must be on Mars around midnight. At least that’s what NASA’s InSight lander is finding as it probes the planet for clues to its history, National Geographic reports. The robotic geophysicist—which is recording tremors, measuring ground temperatures, etc—also says there’s much more magnetism in the planet’s crust than expected. “We’re getting an insight into Mars’ magnetic history in a way we’ve never had before,” says a planetary geologist. First, a primer: Earth and Mars each have a magnetic field. Earth’s is caused by a liquid, iron-rich outer core that’s been shifting for a very long time. Sadly, Mars’ field collapsed about four billion years ago and became a much weaker version of itself.
That meant it could no longer protect Mars from the sun’s radiation, or solar wind, which wore down much of the planet’s atmosphere. Now InSight says Mars’ magnetism is roughly 20 times stronger than expected, suggesting its magnetic field lasted longer than scientists had thought. As for the pulses, they oddly occur at midnight local time. Maybe that’s because the solar wind, when hitting the planet’s thin atmosphere, creates a weak magnetic bubble that gets compressed into a kind of tail shape—and InSight is aligned with that tail at midnight. InSight has also found an electrically conductive layer far below Mars’ surface that could be a planet-wide reservoir of water roughly 2.5 miles thick, per Big Think. And that could mean life, either current or long gone. (Read more Mars stories.)