The moon is the most obvious and familiar object in Earth's night sky - constant, consistent, predictable in its monthly cycles and its daily rising and setting. Astronomers understand the moon's movements so thoroughly that even a break from the routine, like an eclipse, can be anticipated 1,000 years in advance.

But we don't know the moon as well as we think. In fact, for years, astronomy has been in an uproar over the origin of Earth's only natural satellite, grappling to make sense of a model that seems increasingly unsatisfactory.

Could the moon have been formed from several pieces of space debris? Credit:Getty Images

Now, a team of Israeli researchers has shaken up the debate by offering an entirely new explanation, published this week in the journal Nature Geoscience. They say the moon isn't a single chunk of rock but an amalgamation of nearly two dozen "moonlets," one that was formed during a steady bombardment of Earth by several smaller bodies.

It's a major departure from the "giant impact model," which was once the standard explanation for the moon's existence. That hypothesis proposes that the satellite came about during a single, violent collision between Earth and a hypothetical protoplanet called Theia. Theia sideswiped our planet roughly 4.4 billion years ago, scattering debris that eventually coalesced into the moon, which drifted away and started to circle the Earth.