Thursday, July 17, 2008

Moon in the Balance

I am torn.

As an amateur astronomer, I must arrange my observing life around avoidance of the Moon; wait impatiently for it to set; nervously watch the eastern horizon for its arrival; hide from it behind trees, rock outcroppings, vehicles, and outhouses; wail and curse it when it appears. Let’s face it, that old incandescent Moon is the bane of every hunter of "faint fuzzies": deep-sky objects pursued with telescopes, binoculars, and much lurching about in pitch-dark places.

Faint Fuzzies: Hickson 44 galaxy group

As a human being, though, I must marvel at the Moon and think how lucky we are. We have a natural satellite that shows us, through its phases, that it revolves around us. When it covers the Sun during a solar eclipse or moves into the Earth’s shadow during a lunar eclipse, we have a glimpse into the clockwork of the universe. We have a naked-eye view of the surface of another solar system body. We even have a cosmic timepiece that ticks along reliably enough to give us the basis for our system of calendar months. (Did you know the word month is derived from the Old English word for moon, mona?)

The approach of Full Moon on Friday the 18th has me pondering what I’d do if given the power to choose between keeping the Moon or banishing it forever. A giddy free-for-all of deep-sky diving, unfettered by the lunar cycle, versus a glowing orb that has inspired humans throughout history to pen poems, create art, write songs, do science, and pitch woo. The everlasting happiness and gratitude of my stargazing brethren versus the artistic, scientific, and romantic outpourings of the human race. It would be a tough call.

There are some practical reasons to keep the Moon. In a previous post, I discussed precession, the slight wobble of Earth’s axis. This wobble is caused by gravitational tugging by both the Sun and the Moon. If the Moon were removed from the picture, Earth’s wobble would destabilize, becoming more erratic and pronounced. This would most likely result in dramatic climate changes.

Image courtesy of

Another reason to hang on to our satellite has to do with tides. The combined gravitational pull of Sun and Moon causes the cyclical rise and fall of Earth’s oceans, the tides. Although the removal of just the Moon would not eliminate the tides, it would certainly disrupt them. The feeding and breeding activities of various marine and shore creatures could be severely impacted.

Even if we subtract these practical considerations from the equation, ultimately I think I’d miss the Moon if it were gone. I’d miss how the waxing crescent looks like a big, happy tangerine slice before it sets, and a crescent in the clouds like a shark fin slicing through seafoam. I’d miss that loopy Moon illusion that makes the rising Full Moon look unnaturally big. I’d recall the lunar eclipses I’ve watched and how the Moon in Earth’s shadow always turned red--sometimes russet, sometimes scarlet. I’d miss the gasps and whoops that a telescopic view of the Moon’s crater-pocked surface elicits at public astronomy events. I’d miss my own telescopic tramps across the Moon and moments of discovery. Strangely, I think I’d even miss the collective groan that rumbles across a star party’s observing field when the Moon bobs up in the east.

Observing field at a star party

So, at the end of the day, with all that fateful power at my fingertips, I’d have to give La Luna the thumbs-up. Of course, I’d also have to change my name, move out of state, and never show my face at another star party. Anywhere. Perhaps we should keep this just between us.