Tonight's Sky
Sun
Sun
Moon
Moon
Mercury
Mercury
Venus
Venus
Mars
Mars
Jupiter
Jupiter
Saturn
Saturn

Tonight's Sky — Change location

OR

Searching...

Tonight's Sky — Select location

Tonight's Sky — Enter coordinates

° '
° '

Previously understood that magnetic fields were directly related to rotation, so when I read that Mars, like Venus, didn't have one, my understanding crumbled. What exactly causes magnetic fields in planets?

Kerry Dougan, Jarabacoa, Dominican Republic
RELATED TOPICS: MAGNETIC FIELD
Mars InSight lander
Planetary magnetic fields are definitely related to rotation, but “directly” — not so much. They are actually generated by the complex interaction of fluid currents (motion of material) and electric currents (motion of electrons) in the conducting fluid of the molten metal core. This is called a “dynamo,” and core convection is its primary driver, powered by cooling and crystallization growth of the solid inner core.

Astronomy magazine subscribers can read the full answer for free. Just make sure you're registered with the website.

Already a subscriber? Register now!

Registration is FREE and takes only a few seconds to complete. If you are already registered on Astronomy.com, please log in below.
ADVERTISEMENT

FREE EMAIL NEWSLETTER

Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter.

ADVERTISEMENT
ADVERTISEMENT
asy_gravitational_eguide

Click here to receive a FREE e-Guide exclusively from Astronomy magazine.

Find us on Facebook