THE SOUTHWORTH PLANETARIUM
207-780-4249      www.usm.maine.edu/planet
70 Falmouth Street     Portland, Maine 04103
43.6667° N                   70.2667° W
Founded January 1970
Julian date:  2457762.16
                 “Tomorrow belongs to those who can hear it coming."
                                         -David Bowie


*THE DAILY ASTRONOMER*
*Tuesday, January 10, 2017*
*More Than One Wham?*


About four billion years ago,or thereabouts, a small, spherical body, still
warm from the fierce heat of formation, was wandering through the infant
solar system.   Though significantly smaller than most of the major bodies
that had just congealed out of the primordial nebula, this rock ball was
nevertheless physically formidable.    It was also rather content with its
isolation, being naturally inclined toward solitude rather than
companionship.   Suddenly, as it meandered through the inner solar system,
it came upon Earth. It was not the verdant,blue-green world with which we
are familiar. It was a harsh, toxic world suffocated by noxious gases
pressing down on a paper-thin crust that was still often lacerated by
exposing veins of molten rock.           The interloping body saw Earth.
   Earth saw the interloping body.     The immediate attraction drew them
closer together.  Though their initial mutual approach was rather
tentative, as their separation distance decreased,their approach speeds
accelerated.     Faster and faster, through the impulse of mutual
attraction, they approached even close and,embracing destiny, the two
bodies collided with a world-shattering bang!

Or, more technically, a WHAM!

The impact energy annihilated the small interloper and gouged out a big
portion of the infant Earth.  Vaporized material from both bodies scattered
into space.     It then quickly solidified and congealed to form the moon.

This introduction,   including the romantic insinuation, summarizes the
Wham Theory:  the notion that a violent collision between Earth and an
errant body formed the moon. This theory arose after analysis of the Apollo
moon samples showed that the moon was both chemically similar and
dissimilar to Earth. Had the moon merely been a captured body, as once
believed, it would have been wholly dissimilar to Earth. Had the moon been
a piece of Earth that had detached, also as once believed, it would have
been similar to Earth.

The Wham Theory seemed to explain the chemically similarities and the
chemical differences between Earth and the moon. However, recently
 researchers have developed computer simulations that replicated the
conditions that prevailed during the epoch of the early solar system
 These simulations suggest that the moon didn't form after just a single
impact.  Instead, multiple impacts may have formed an array of "mini
moons."   These little bodies would have then coalesced into the larger
moon we see in our skies now.



*​The moon might have formed out of an agglomeration of smaller
"mini-moons,"*
*as opposed to having formed after a single impact between the infant Earth
and a Mars-sized body. *

This new, "mini-moon amalgamation" theory assumes that the early solar
system was such a violent place where collisions were common.      Any
significant impact would have displaced matter from the largely molten
Earth.  This material would have then formed  a small moon.   The small
moons created by these minor impacts would then eventually collide to
produce larger bodies. Ultimately, these series of collisions would have
created the single moon.

So, it is possible that the moon contains even more Earth material than
once assumed. Moreover, that serene orb that silvers our forests and casts
luster onto snow fields might have been born out of an unimaginably violent
series of devastating impacts.