Lady Di: Nuisance or Inspiration?

While we’re still waiting on that I-max show above us to significantly change, let’s take a few minutes to focus on what arguably is THE primary attraction of our night sky, approximately half the days of any given month: “Lady Di”, a.k.a. the moon!

Waning gibbous moon, mid-morning

Waning gibbous moon, mid-morning

Love her or loathe her (a lot of amateur astronomers do, in the case of the latter sentiment), that bright orb is here to stay, even if it is the constant bane of the Deep Sky Observer’s existence. Our lonely satellite is currently dominating the evening sky, waxing-growing in size-toward its first-quarter phase. Problem with the moon is that, regardless of how many scenes in TV shows and movies where the full moon is surrounded by hundreds of pristine stars, moonlight in reality washes out all faint objects in the same sky. With the exception of a bright planet or two, any stars lower than about second magnitude are effectively rendered invisible by the moon’s brilliance (after all, it’s the second-brightest object in our sky, after our own sun!).

Full moon, pre-dawn

Full moon, pre-dawn

I’ve been a strong advocate for detonating the moon. Romantics are already howling in protest. Presumably werewolves, too. I used to fantasize about blowing it up, till I realized that would result in hundreds or thousands of fragmentary “moonlets”, several of which would be in our sky every night! I’d love to have a dollar for every time I’ve announced that I wished I could take advantage of a preternaturally clear evening to go out observing, followed by someone saying, “What a shame, too…there’s gonna be such a beautiful moon tonight!”

Waning crescent moon, pre-dawn

Waning crescent moon, pre-dawn

Well. Given that Lady Di’s going to be on exhibit tonight regardless of whether it’s convenient for me, let’s turn those binoculars or that telescope her way. I stated earlier that Saturn was the ultimate first celestial showpiece…and I stand by those lofty words. But even our ringed planet is diminished by the sheer beauty and detail visible on our moon’s craggy, cratered surface (at a mean distance of 240,000 miles versus Saturn’s average distance being 800,000,000 miles from Earth, just a bit closer; hence more detail). I’ve heard exclamations of sheer joy…and a few expletives too, from folks lined up to gaze through my big refractor. The craters, especially those in sharp relief against their shadows along the “terminator” (that line where her position in her orbit relative to Earth cuts off the visible portion of the moon), are just visually stunning. Of course the higher the magnification, the “closer” you get. With a high-power eyepiece, the view starts to resemble what the Apollo astronauts got to see, orbiting the moon.

And of course the moon’s phase changes, night to night. It’s growing for the remainder of this week, culminating with being full early next week. If you can catch it, between slim crescent and first quarter half-moon phase-and if you have a telescope-look closely at the surrounding few stars. You might get lucky, and spot a star close to the moon’s unlit side. Chances are, if you gaze long enough, you will notice the moon getting closer to the star…sometimes the moon will “creep” up, and appear to eat the star, as our satellite passes in front of the much more distant star (that’s an understatement). Because the star is so, so much farther away than our moon ( half an inch versus a couple of thousand miles!), the star will “wink out” instantly. Blink, and you’ll miss it. This is called an occultation. It occasionally happens when the moon “eats” a planet within our solar system. I’ve watched the moon occult Saturn twice, the last time back in 2001. Because Saturn is relatively close-relatively speaking!-it took several seconds for the ringed planet to disappear behind the our satellite…approximately an hour later, it emerged again, from the opposite side of the moon!

All of that said, I have to confess I’m not a “moon aficionado”. But perhaps for you, this might become a primary attraction in the night sky. There’s a lot to take in.

One final anecdote, dating back to when I had that first 60mm refractor: a cousin of mine, gazing at the moon through my instrument, asked if he could see “the flag on the moon”, left by Apollo astronauts. I arched an eyebrow-all of twelve years old-and asked, “Which one? There are five of ’em up there!”

Lest there be any misinterpretation of my pre-pubescent, carefully-honed sarcasm, even the Hubble Telescope’s resolution cannot show any of the Apollo landing sites. Its optics, when turned upon our moon, can only resolve down to fifty square meters (versus about a hundred square miles, given high magnification, for most backyard telescopes)…and the lower stage of the lunar modules stranded up there is about thirty-five square meters, so…

Did we actually go, or not?

Stay tuned.

Waxing gibbous moon, late afternoon

Waxing gibbous moon, late afternoon

Clear (albeit it moon-infested) Skies,

Jesse

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