Our Own Spectacular Moon

The moon will be full, this Friday, a visual gift that keeps on giving (approximately 12 times a year). Its light dominates the sky, impeding vivid naked-eye observation of background or nearby constellations. Friday night, for example, the moon will be found in that part of the sky known as Aries, which means that the stars of Pisces, Aries and Taurus will yield the floor to the great but graceful lunar disc.

When winter comes, a number of Taurus’ sublime constituents and companions will grow familiar, Aldebaran and the "seven sisters" of the Pleiades, to name two. But this week, make eye contact with the "man in the moon." You know that face will be there — staring at you from the same angle it always does. No matter what month or year, our sole natural satellite never turns its back on us.

We Earthlings always gaze at approximately the same eerily humanoid map — chiefly characterized by a left eye called "Mare Imbrium," ("Sea of Rain"), a right eye called "Mare Serenitatis" ("Sea of Serenity") and a mouth called "Mare Nubium" ("Sea of Clouds"). These lunar seas are not actual water bodies, but large, low, flat and iron-rich plains formed by ancient volcanic eruptions. Their depth and iron content produce pockets of darkness with which we grow almost unconsciously familiar.

Certainly, the moon possesses a "back" and it often gets illuminated by the sun. No extra-terrestrial neighbor of ours (imagined or discovered) would understand what we meant by the moon’s "dark side." So does the moon really refuse to spin for us?

No. The reason for an omnipresent countenance and an eternal "dark side" is simply a beautiful twist on the nature of twists. It turns out that the moon spins almost exactly one time on its axis for every one time it orbits our planet. That is, a month on Earth takes essentially a day on the moon. The moon and Earth have, over the ages, fallen into this unusual but stable harmony. It would not be fair to call it a "coincidence," but our relationship certainly could have played out an infinitude of other ways — as it did for Mars and its two moons, or Jupiter and its 63.

For a one-moon family, we really shopped at the right place at the right time.