February 20, 2020

Observations: On the Beach

On the Beach…

(photo by author)

Astronomy isn’t the first thing you think of when you consider spending the day at the beach.

We recently moved our Astroguyz mobile HQ to Pass-a-Grille Beach, a small community in Saint Petersburg, Florida. A small spit of land jutting out into the Gulf of Mexico, Historic Pass-a-Grille has thus far resisted the encroaching sea and the creeping Florida gentrification that has plagued much of the state and Tampa Bay in particular… yes, you can still find lazy, quiet corners of beach, even in the looming shadow of the twin cities of Tampa/St Pete.

Sure, the beach isn’t the first place you think of when it comes to astronomy. Astronomical observing conjures up images of forlorn windswept mountain tops, places with thin air and good seeing… but this sort of ideal locale is also far from our front door.

Often, you’re observatory is where you make it, from a wide open desert sky to an overlit suburban rooftop. Over the years, we’ve learned not to curse our circumstances, and instead, work with what we’ve got. We’ve made dark sky estimations from such unlikely locales as the Strip in Las Vegas whilst awaiting transport to the airport, under arguably the most light polluted skies on Earth. I could juuust pick out the Belt of a half-erased Orion under such a white-washed sky, as those ancient stars did battle with the garish Vegas lights.

I’ve thus come to appreciate the beach. There’s something about the seamless transition on sand, sea and sky that not only has an aesthetic appeal to the classic rule of thirds straight out of photography 101, but simply invites people to actually look at the sky.

Some of the most mythical dark skies can be had, at the center of the ocean, far from the city lights. We also learned during our trip down to Longboat Key that sea turtle conservation means dimmed lights for beach residents, another plus.

You also see the first hand effects of astronomical objects at the beach. The most obvious, of course, are the tides. The tug of the Sun and the Moon are of immediate interest to those who live and work along the beach. And though distant horizon looks like a line straighter than any you could ever draw by hand, you can watch ships disappear “mast last” over the curve of the planet.

This same curve allows folks to glimpse the elusive “green flash” of refracted light as the Sun sets below the horizon, through I always like to warn folks that it’s more of a subtle pale pea green than a verdant glow.

You’re also witnessing something at the beach that’s common on Earth, but rare in the solar system: a planet which wears its oceans on the outside. Only one other world—Titan –has extensive external seas, with lakes of liquid methane and ethane dotting its chilly surface. Where did all that H2O come from? It’s one of the major mysteries in planetary formation, but our seas serve to not only lubricate the tectonic plates of the Earth, but serve as a major heat sink, moderating planetary climate. The oceans are also a major repository of all the hydrogen on Earth, the “H” in H2O.

Some folks like the mystery of the seas, though I’ve always felt that knowing the science behind the veil makes things even more awe inspiring. The even in our modern selfie stick era the beach inspires a quiet sense of contemplation. This is most evident during our morning run, when the beach is ruled by walkers, fishermen, and many who have driven down, simply to witness the dawn.

And heck, we just love the clear horizon uncluttered by buildings or trees. Lots of astronomy takes place low to the horizon, and its never a battle to find a clear view, clouds willing.

It’s sad to think that, as sea levels continue to rise, that the world’s beaches could disappear this century, sure, there’ll always be intertidal zones, but the areas of sandy white beaches that took millions of years of erosion to create will be a thing of the past. Perhaps, we’ll still make artificial beaches in their honor, but we’ll have lost something crucial to the human experience here on Earth.

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