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

° '
° '

As Earth was molten early during its formation, dense metals should have sunk toward the core, yet iron is found closer to the surface. Did asteroids and comets deliver some of these materials?

Douglas Kaupa, Council Bluffs, Iowa
RELATED TOPICS: EARTH
Planet impact
This question has long puzzled planetary scientists. Shortly after our planet took shape, it was bombarded by planetesimals — rocky objects that hadn’t yet coalesced into worlds. Astronomers expected these iron-rich bodies would sink to the core after impact. Instead, we now know iron is found scattered throughout Earth’s mantle.

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