It is the Harvest Moon!

photo credit: harvest moon 2011 II via photopin (license)

Here in New England, the long summer has abruptly receded, and a series of cool nights have signaled the arrival of fall. The maples, among the first to sense the changing seasons, have slowed their production of chlorophyll, and the first bright colored leaves have begun to peek through the canopy. This year, the changing of the seasons is coupled with a unique combination of astronomical events: Sunday’s full moon, the Harvest Moon, will additionally be both a supermoon and a “blood moon” lunar eclipse. These terms seem ripe for poetry on their own. But what do they really mean?

It is the Harvest Moon! On gilded vanes
And roofs of villages, on woodland crests
And their aerial neighborhoods of nests
Deserted, on the curtained window-panes
Of rooms where children sleep, on country lanes
And harvest-fields, its mystic splendor rests!

Henry Wadsworth Longfellow’s poem, “The Harvest Moon,” depicts a still nighttime scene presided over by a Harvest Moon, in all its “mystic splendor.” The term “Harvest Moon” is applied to the full moon closest to the autumnal equinox. The Harvest Moon, which usually occurs in September, historically allowed farmers to continue their harvest into the night. Other, related, names for the September full moon include the Barley Moon and the Corn Moon.

The Harvest Moon is special for another reason. At the time of the Harvest Moon, the moon rises at about the same time for several nights, making it seem like the moon is full multiple nights in a row. This occurs because of the angle of the moon’s orbit relative to earth’s. Because the moon’s orbit is offset from earth’s orbit, the moon usually rises about 50 minutes later each successive night (that is, the time between sunset and when you see the moon increases by about 50 minutes from night to night). But around the time of the autumnal equinox, the moon’s orbital path makes a shallow angle with the horizon, so for a few days before and after the harvest moon, the moon rises only about 30 minutes later than it did the previous night. This happens around sunset, so what we see is a large, bright moon lingering around the eastern horizon just as it gets dark.

In 2015, our Harvest Moon is even more special than usual. This year, it is also a supermoon lunar eclipse, a phenomenon that hasn’t happened since 1982 and won’t happen again until 2033.

A supermoon is caused by the shape of the moon’s orbit. Because the orbit is elliptical, sometimes the moon is closer to the earth than other times. At its closest approach to earth, called perigee, the moon is about 31,000 miles closer to us than when it’s at its farthest point, called apogee. If a full moon coincides with perigee, we call it a supermoon because its proximity makes the moon look about 14 percent larger and 30 percent brighter than a normal moon, according to  NASA.

Which brings us to the “blood moon” lunar eclipse. A lunar eclipse occurs when the earth lines up between the sun and the moon, blocking the sun’s light from falling on the moon. In the shadow of our planet, the moon appears reddish.

If the earth didn’t have an atmosphere, the moon might appear completely dark during an eclipse. Instead, sunlight bends around the earth and is filtered through the atmosphere, which removes blue light but allows red and orange light to reach the moon’s surface. What we see when a lunar eclipse is at its peak, is a blood-colored moon.

On Sunday, if the weather is clear, we should see a huge, bright moon that appears red for a few hours while it is eclipsed. Stand out in its light to celebrate, or mourn, the end of summer. The birds are leaving, the leaves are falling, and the chill wind wraps us as we reap whatever harvest this year has brought to us.

Gone are the birds that were our summer guests,
With the last sheaves return the laboring wains!
All things are symbols: the external shows
Of Nature have their image in the mind,
As flowers and fruits and falling of the leaves;
The song-birds leave us at the summer’s close,
Only the empty nests are left behind,
And pipings of the quail among the sheaves.

REFERENCES

“The Harvest Moon,” by Henry Wadsworth Longfellow. Read it here.

Byrd, Deborah. 2015. “Everything you need to know: Super Harvest Moon of 2015.” EarthSky. Link.

Morrow, Ashley. 2015. ” NASA Scientist Sheds Light on Rare Sept. 27 Supermoon Eclipse.” NASA. Link.

Palmer, Katie M. 2015. “Here’s Where to Watch the Supermoon Eclipse Online.” Wired. Link. 

“Why a Totally Eclipsed Moon Looks Red.” 2015. EarthSky. Link.

Each bolt a burning river

The oaks shone

gaunt gold

on the lip

of the storm before

the wind rose, 

the shapeless mouth 

opened and began

its five-hour howl;

the lights

went out fast, branches

sidled over 

the pitch of the roof, bounced

into the yard

that grew black

within minutes, except 

for the lightning–the landscape

bulging forth like a quick

lesson in creating, then

thudding away.

 

The opening lines of Mary Oliver’s poem “Lightning” are rapid-fire and breathless as the author describes the onset of a storm.  Summer is the time of year for thunderstorms, and in New England, we have been beset by one after another for days on end.  Do you remember being a child in a thunderstorm?  Perhaps you were afraid or enchanted or awed as the sky seemed to rip apart and you could imagine the earth itself trembling.  As adults, we have learned to stifle our most primal urges, yet a thunderstorm still gives us pause.  Step onto your porch or front step on a muggy afternoon just as those distant growls begin, smell the ozone and electricity in the air, and for just a moment, you can allow that same fear or enchantment or awe to take you over.

In order for a thunderstorm to form, there must be moisture and rapidly-rising warm air.  Since both moisture and warmth are required, thunderstorms occur most often in the spring and summer.  Once a thundercloud is formed, a charge separation develops within the cloud.  The inside of a cloud contains turbulent winds, water droplets, and suspended ice particles.  Drops of water in the bottom part of the cloud are lifted by updrafts to the colder top of the cloud, where they freeze.  At the same time, downdrafts within the cloud push the frozen ice and hail down from the top of the cloud.  As the falling ice meets the rising water, electrons are stripped off, creating a charge separation in the cloud.  The lost electrons accumulate at the bottom of the cloud, giving it a negative charge, while the newly positive unfrozen droplets continue rising, giving the top of the cloud a positive charge.

Charge distribution inside a storm cloud. (www.nssl.noaa.gov)

The cloud now has an electric field associated with it, one whose strength depends on the amount of charge in the cloud.  When the negative charges at the bottom of the cloud become strong enough, they actually repel electrons on the Earth’s surface, causing  a strong positive charge, which moves up to the top of the tallest objects. When the strength of the cloud’s negative charge overcomes the insulating properties of the surrounding atmosphere, lightning results.

The strong electric field in the cloud now creates a channel called a “stepped leader” which descends from the cloud seeking a path to the ground  (this happens faster than the human eye can see).  As it nears the ground, the negative charge is met by what’s called a “streamer” of positive charge that reaches upwards from the tallest object.  When the leader meets the streamer, a powerful electrical current begins to flow, and we see what we call “lightning” as  a return stroke barrels back up to the cloud at around 60,000 miles per second.  A lightning flash can contain as many as 20 return strokes.

Inside,

as always, 

it was hard to tell

fear from excitement:

how sensual 

the lightning’s 

poured stroke!  and still,

what a fire and a risk!

 

Slow motion lightning. Note the stepped leader prior to the strike!

Thunder is caused by the creation of lightning.  In a fraction of a second, the lightning channel heats the surrounding air to temperatures around 18,000 degrees Fahrenheit.  The heated air expands rapidly, and causes a sound wave called thunder.  The different sounds we hear in a thunderstorm correspond to the different stages of the lightning strike: the initial tearing sound is caused by the stepped leader, the ground streamer causes the click heard at close range, and the main crash of thunder is caused by the connection between the two and the enormous amount of energy generated in a lightning “bolt”.  The reason why our perception is that thunder occurs after lightning is because light travels so much faster than sound.

So what explains the way we react to a thunderstorm?  What is it about electricity, noise, and light that results in such a visceral response in many people?  It is possible that thunderstorms are merely the most common way many people come in contact with nature on an epic scale; natural events like tornadoes and hurricanes, while terrifying, are much more rare.  There is a name for a fear of thunderstorms: astraphobia.  It occurs in adults as well as children, and is listed among the top phobias in the US.  Sufferers experience symptoms of anxiety, as well as increased interest in weather forecasts.  So in some cases, people never feel entirely safe with this weather phenomenon.  Some never escape that childhood feeling of powerlessness.

Mary Oliver’s poem swiftly and beautifully leads the reader from the rapid buildup of a storm through to its violent height.  The speaker is both terrified and excited–electrified, one might say–by the power all around.  Once again, I am amazed at how much science can be divined by the pure emotion of a natural event.  Oliver’s sensitivity to this storm allows her the ability to describe both the internal and external chaos:

As always the body

wants to hide,

wants to flow toward it–strives

to balance while

fear shouts,

excitement shouts, back

and forth–each 

bolt a burning river

tearing like escape through the dark

field of the other. 

 

REFERENCES:

“Lightning,” by Mary Oliver.  Read it here.  

“Lightning Basics.” National Severe Storms Laboratory: NOAA.  Link.

“Thunderstorm Basics.” National Severe Storms Laboratory: NOAA.  Link.

“What Causes Lightning and Thunder?” SciJinks: NASA.  Link. 

Weeds where woods once were.

“Between forest and field, a threshold

like stepping from a cathedral into the street–

the quality of air alters, an eclipse lifts,

 

boundlessness opens, earth itself retextured

into weeds where woods once were.”

 

Ravi Shankar’s poem “Crossings” describes something quite familiar to us all: the edge of the forest.  The speaker is struck by the clear division between a forest and a field, by how different it feels, even, to step from one to the other, from the cathedral-like hush of the forest under the canopy to the wide-open world of a field.  What Shankar is describing here is, in fact, an ecological phenomenon, one called an ecotone.

An ecotone is a transition between two biomes and can be regional (such as between an entire forest and grassland ecosystems) or local (such as the line between a forest and a field).  The name comes from the Greek  words oikos, meaning household or place to live (“ecology” is the study of the place you live!) and tonos, or tension.  So an ecotone is a place where two environments are in tension.

The most interesting part of an ecotone is how it allows for blending of the different organismal communities.  On either side of the boundary, species in competition extend as far as they can before succumbing to other species.  The influence of these two communities on each other is called the edge effect.  Some species actually specialize in ecotonal regions, using this transitional area for foraging, courtship, or nesting.

Terrestrial environments are not the only ones in which we can experience Shankar’s “threshold” between biomes.  There are also land-to-water ecotones, such as marshes or wetlands, and strictly aquatic ecotones, such as estuaries, where a river meets the sea.  Perhaps in these more dramatic transitions it is easier to see how some species can thrive in this unique habitat.

Even without knowing the biology behind ecotones, it is possible to sense the tension inherent in this boundary.  When hiking on a hot summer day, when the trail leads into a forest it’s like an exhalation.  We, as animals, sense the natural world much more acutely than society would like us to believe.  Ravi Shankar, using the skills of the poet to express what the rest of us cannot verbalize, notes this feeling, writing:

Even planes of motion shift from vertical

 

navigation to horizontal quiescence:

there’s a standing invitation to lie back

as sky’s unpredictable theater proceeds.

 

Suspended in this ephemeral moment

after leaving a forest, before entering

a field, the nature of reality is revealed.  

 

REFERENCES:

“Crossings,” by Ravi Shankar.  Read it here.

“Ecotone.”  Wikipedia.  Link.

Senft, Amanda.  2009.  Species diversity patterns at ecotones.  (Master’s thesis). University of North Carolina.  Link.

Alive beyond compare.

“…the heart, exposed exactly for what it is: homelier

than we’d like to imagine.  And alive beyond compare.  

Here, the heart is the heart, and isn’t

a fist or a flower or a smooth-running engine

and especially not one of those ragged valentines

someone’s cut out, initialed, shot full of cartoon arrows:

the adolescent voodoo of desire.  Here, nothing’s colored

that impossibly red.”  

 

In honor of the holiday, I’d like to consider the human heart.  No, not the one usually found in poetry, but the one actually inside of you; the one functioning to carry blood throughout your body, the one transporting oxygen and nutrients and chemicals to every extremity.  David Clewell’s poem “Not to Mention Love: A Heart for Patricia,” is, as the title implies, a love poem written (almost) without the word “love”.  Clewell has tried to

“keep the heart in its proper place for once.  It’s not

in my mouth or on my sleeve  or winging its way lightheartedly 

in circles over my head.  It’s more or less right

where it belongs inside of me, no small thing.”  

 

So, dispensing with hyperbole and flowery romantic language, what we have left is the heart itself.  Put most simply, the heart is just a muscular pump.  But what is its function?  And how does it work?

Inside your heart are four chambers (fun fact: while mammals have four chambers, reptiles and amphibians have three, and fishes, without the need to breathe air, have only two).  The top two are the left atrium and right atrium (plural: atria), and the lower two are the left and right ventricles.  (The “left” and “right” designation always refers to the animal/person whose heart it is: so if a surgeon was looking down a patient, the left ventricle would be on the patient’s left).  Each chamber bears a one-way valve so that when the chamber is contracting, blood can come in, but when the muscles relax, the valve is shut.

The heart works with a two-stage contraction (the contraction phase is called “systole”).  In the first stage, the right and left atria contract simultaneously, pumping blood through their associated valves into the right and left ventricles.  In the second stage of contraction, the right and left ventricles contract simultaneously to push blood out of the heart.  This two-stage process is why you hear a heartbeat as two sounds “lub-DUB”–that’s the sound of your heart valves closing.  After the contraction, the heart muscle relaxes, a phase called “diastole.”  As Clewell writes,

“There’s nothing cute about it.  The heart 

is the heart, chamber after chamber.  Ventricular.  Uncooked.  

In all its sanguine glory.  I couldn’t make up a thing

like that.  The heart’s perfected its daily making do, the sucking

and pumping, its mindless work: sustaining a blood supply

that’s got to go around a lifetime.”  

 

(This last point is not exactly true.  Blood is, in fact, produced in the bone marrow).  In their contractions, the right and left sides of the heart fulfill different functions.  Blood returning from the body is oxygen-poor and enters the right side of the heart (atrium to ventricle).  The right ventricle sends this blood out to the lungs to be oxygenated (and to release carbon dioxide).  This blood then returns to the left side of the heart (atrium to ventricle again) where the much-larger left ventricle pumps oxygenated blood out to the entire body.

But it’s Valentine’s Day!  What about love?

What we call “love” is a combination of emotional attachment and brain chemicals.  Though we may seem to feel things in our “heart”, the heart really has only one thing to do with love: it acts to circulate the aforementioned brain chemicals (dopamine, serotonin, and oxytocin) in the blood out to the body and all the rest of the organs, where they can have the physiological effects that make us feel love.  Does this mean love is all in our heads?  Not at all.  It’s everywhere inside of us, thanks to our powerful hearts.

“Sure, there’s a brain somewhere, another planet,

just seconds or light-years away, and maybe some far-flung

intelligence madly signalling for all it’s worth–

but the heart wouldn’t know about that.  It has its own

evidence to go on.  What’s convincing to the heart

is only the heart.  It doesn’t have the luxury of stopping

to weigh, to reconsider, to fold and unfold the raw data of the world

until it’s creased beyond recognition.  Some days it can’t distinguish 

a single sad note from a chorus of exhilaration, but still

the heart has its one answer down to a science: yes.  Over

and over, the iambic uh-huh.  Whatever it takes, some kind of nerve

or unlikely grace: the heart never knows what to think.”

 

REFERENCES:

Bianco, Carl.  1999.  “How Your Heart Works.”  HowStuffWorks.com.  Link.

“Biological basis of love,” Wikipedia.  Link.

Boston Scientific.  2009.  “Heart Valves.”  Link.  (Check out the cool animations on this site as well!)

“Not to Mention Love: A Heart for Patricia,” by David Clewell.  Read it here.

Wilson, Sue.  2002.  “Red Gold: the Epic Story of Blood.”  pbs.org.  Link.

A Wilderness of White

Photograph of a natural snowflake captured with a specially designed snowflake photomicrograph. Photo: snowcrystals.com

“How full of creative genius is the air in which these are generated!  I should hardly admire more if real stars fell and lodged on my coat.”

 -Henry David Thoreau

 

In the northeast, winter is a season of cold.  It is a time when outdoor activities are dictated more than ever by the weather.  As children, snow is the stuff of dreams.  It can be mounded, piled, thrown, shaped, dug out, eaten, colored, ridden on, and experienced in a million ways.  As if that isn’t enough, the enduring hope of snow day is ever present, and the moment when you first wake up to that brightness of reflected sunlight through your windows, when you wake up and know it will be a day for only fun, is the lightest feeling in the world.  As adults, snow is polarizing: you love its beauty or hate its inconvenience.  Everyone has heard that every individual snowflake is unique.  But is this true?  And if so, why?

“Out of the bosom of the Air,
Out of the cloud-folds of her garments shaken,
Over the woodlands brown and bare,
Over the harvest-fields forsaken,
Silent, soft, and slow
Descends the snow.”

-Henry Wadsworth Longfellow 

 

First off: a definition of terms.  Snowflake is a more general term, and can refer to an ice crystal, a single crystal of ice, or to larger clumps of ice crystals that fall in agglomerations.  An ice crystal is not a frozen raindrop.  Liquid water that freezes and falls to the ground becomes sleet.  Rather, ice crystals are formed when water vapor in the clouds condenses directly into ice.  As you may (or may not) remember from chemistry class, ice crystals, each molecule of which is made of an oxygen atom and two hydrogen atoms, form what is called a hexagonal lattice.  The six-sided symmetry of this lattice is what gives snowflakes their six-sided symmetry.  Elaborate patterns emerge as the ice crystals grow in the clouds.

The most basic form of a snow crystal is a hexagonal prism, which includes two basal facets and six prism facets.  Different shapes can occur under different conditions, and the form of a snowflake depends very heavily on temperature and humidity.  The growth of these crystals relies on a balance between branching and faceting.  Branching is due to a property of water molecules and the way they travel through the air: they must diffuse, and thus the surface of a crystal a water molecule reaches first is the one one which it condenses.    A small bump on an otherwise-homogeneous structure is thus more likely to result in a crystalline branch, and once a branch has formed, it is more likely to grow longer.  Facets, on the other hand, are due to the fact that some surfaces of ice crystals grow more slowly than others.  Unlike a bump on a crystal surface, inviting a water molecule to bond, the flat surface of a facet is more likely to remain smooth because there is nothing for the water molecule to attach to.  Therefore, this surface grows more slowly.

Below, see a general guide for the most common forms of snowflakes:

For all that we understand about crystalline structure and how ice crystals form, there is even more we don’t know.  Why do the most complex shapes form at high humidity?  Why do the shapes of snowflakes go from plates to columns as the temperature lowers?  Usually, each arm of a snow crystal is different from its other arms.  Air current turbulence causes this: as crystals are blown about, water molecules can condense unevenly as each corner of a snow crystal experiences a different environment in the atmosphere.  So there is truth in the unique design of snowflakes, and it is ultimately due to the randomness of nature, building a snow crystal as it is spun and whipped through the air inside a cloud.  John Hallett, director of the Ice Physics Laboratory in Reno, NV, explains that, “[A snowflake’s] final shape is a history lesson of how the thing grew.  The outside edge of the crystal is where it grew last, and as you go inward you can tell where it was before.”

“Before I melt,
Come, look at me!
This lovely icy filigree!
Of a great forest
In one night
I make a wilderness
Of white”

-Walter de la Mare

 

The winter has come, and with it, the cold.  Snow has been sparse in this part of the country the last few years, and all we can do is watch and wait.  Will we awake tomorrow morning with the light bright and snow-shattered through our windows, with a kiss of frost on the glass from a storm like those when we were children?  If so, take a minute and think about how these amazing ice creations came to be.  And then go make a snowman.

REFERENCES:

Griffin, Julia 2011.  The science of snowflakes, and why no two are alike.  PBS Newshour.  Link.

SnowCrystals.com.  Kenneth G. Libbrecht 1999.  Caltech.  Link.

“Snow-Flakes,” by Henry Wadsworth Longfellow.  Read it here.

“Snowflakes,” by Walter de la Mare.

Beginning

To me, nature is its own language.  All we can do is struggle to express, in our own feeble way, what the world is trying to give to us.  So much poetry has been written in an attempt to describe the simple color of a leaf in autumn, or the way a spider spins its web, or the unfurling of a fern frond in the early spring–so much written, so little understood.

Science has its own language, complex and focusing on minutiae.  One must undergo years of training to speak this language.  The language of science can exclude, it can isolate, but it can answer the questions of how, of why, of where.  Science can look at nature and ignore the beauty to see the molecules and forces, the pigments and chemicals and selective pressures.

To marry science and language is to attempt to bring the wonder back to the mechanics.  Beauty is everywhere.  It is magical and evanescent, but it can be explained.  Here is my attempt.

“I believe in God, only I spell it Nature” – Frank Lloyd Wright