Understanding of
moon’s earliest days
gets even murkier
Suspended in the sky, the moon has stared unblinking at the Earth for billions of years. But new work suggests the placid
sphere’s two faces may belie a violent
childhood — one that involved the death
of a small celestial companion. The
By Nadia Drake
moon may also be lying about when it
was born, by millions of years.
Together, the studies, published in
August in Nature, lend a somewhat
shady character to this perennial source
of both fear and inspiration. With the
Lunar Reconnaissance Orbiter already
keeping a close eye on the moon (SN
Online: 9/18/09) and the recently
launched twin GRAIL spacecraft (SN
Online: 9/20/11) tasked with mapping
its interior, scientists hope to uncover
more clues to the satellite’s past.
Not since the Apollo era has Earth’s
nearest neighbor attracted such atten-
tion and resources.
A shadowed past
Much of the moon’s history remains
unclear, including why the nearside
(right, in this north pole view) is so
different from the farside.
New lunar years
Borg, of the Lawrence
Livermore National
Laboratory in Califor-
nia, and his colleagues
set out to determine
the rock’s age by
comparing levels of dif-
ferent isotopes, versions
of an element differing
in the number of neutrons
in their atomic nuclei.
The rock would reveal
when minerals floated atop the
lunar magma ocean and solidified into crust, marking the moon’s
formation. After looking at the levels
of decaying lead and neodymium isotopes, though, Borg’s team found that
this particular rock was much younger
than expected, and not just by a bit. It
of an element differing
in the number of neutrons
in their atomic nuclei.
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