Huge mystery blob found under the moon's far side

Researchers have discovered something massive lurking underneath the far side of the moon: a mysterious blob with the mass akin to a pile of metal five times the size of the Big Island of Hawaii.

The structure, described in a recent study published in Geophysical Research Letters, sits at least 180 miles beneath the South Pole-Aitken basin—a colossal crater punched into the lunar landscape billions of years ago, when the moon's initially molten surface had cooled just enough for impacts to leave a lasting mark.

The blob is likely related to the crater's formation, and it may be the remnants of an ancient impactor's metal core, says study coauthor Peter James of Baylor University.