Unmasking hidden maria

Tiny clues that reveal the true nature of some lunar light plains.

by Charles Wood

A quick look at the full Moon reveals two main types of lunar terrain: expansive, light-hued regions and large patches of dark material. Closer study shows the bright material to be ancient highlands dominated by impact craters, while the dark regions consist of younger basaltic lava flows (maria) at lower elevations. Maria have far fewer impact craters than do the highlands, implying that by the time maria formed (mostly after 3.8 billion years ago), the rate of crater formation had greatly subsided. By coincidence, the Moon's cratering rate declined to a very low level at about the same time as the start of lunar volcanism, which was caused by internal heating from radioactive decay of thorium, potassium and uranium. Cratering continues today at a low level, while volcanism peaked around…

You're reading a preview of

Australian Sky & Telescope (Digital) - 1 Issue, March 2023

DiscountMags is a licensed distributor (not a publisher) of the above content and Publication through Zinio LLC. Accordingly, we have no editorial control over the Publications. Any opinions, advice, statements, services, offers or other information or content expressed or made available by third parties, including those made in Publications offered on our website, are those of the respective author(s) or publisher(s) and not of DiscountMags. DiscountMags does not guarantee the accuracy, completeness, truthfulness, or usefulness of all or any portion of any publication or any services or offers made by third parties, nor will we be liable for any loss or damage caused by your reliance on information contained in any Publication, or your use of services offered, or your acceptance of any offers made through the Service or the Publications. For content removal requests, please contact Zinio.