THE SOUTHWORTH PLANETARIUM

University of Southern Maine

96 Falmouth Street

Portland, Maine 04103

usm.maine.edu/planet

(207) 780-4249

THE WANDERING ASTRONOMER

Thursday, January  25, 2024

April Eclipse I: The Unfathomable Worlds

[74 DAYS UNTIL THE APRIL 8TH ECLIPSE]

Let's begin this eclipse series with a simple and sobering acknowledgement.    We'll never fathom the Sun, Earth and Moon.  Not for even a nanosecond. 

It's certainly true that we can describe them and evaluate them intellectually.   For instance, the Sun's diameter extends over 865,000 miles and, if hollowed out, could accommodate 1.2 million Earth-sized worlds.    We also know that this hefty behemoth is a weighty sphere.     Plop the Sun on the left side of the scale and one would need to pile 333,000 Earths on the right to attain equilibrium.     Also, and perhaps most importantly, we recognize that the Sun is a prodigious energy generator.  Let's imagine for a disquieting moment that our local power company ran the Sun for just one second and then stuck YOU with the bill.    You would owe an amount equal to America's Gross National Product...over the next ten million years.      Sol emits that much energy every time we blink.  Earth receives only one billionth of that copious outflow.  To put this fraction into perspective, one second equals one billionth of 32 years!   As miniscule a portion as this represents, it's enough to sustain our world.  And, finally, we're aware of its longevity.    The Sun awakened out of its birth nebula approximately five billion years ago and will continue to glow with ever increasing brilliancy for billions of years to come.   

Humans have done the work necessary to understand the Sun: from the Copernican model which set the Sun in its proper place, to the Newtonian mathematics that ascertained its mass to the 18th century transit of Venus voyages that determined its distance -and therefore size- to the geological excavations that measured Earth's age, and by extension that of the Sun, to the nuclear physics that demystified its energy production mechanisms. We're dwarfed by its proportions, dazzled by its brilliancy, and comforted by the assurance that it will continue to both retain Earth with its gravity while bestowing ample quantities of radiant energy onto it long after we homo sapiens have vaporized ourselves into the ages.    

Our scientific reckonings notwithstanding, however, we don't know the Sun.  It's far too remote and its proportions are well beyond the range of our intuition.      For instance, people who have never visited Manhattan still know that the city is a sleepless, bustling, ferociously energetic nuclear reactor of a town.      However, visiting Gotham lends one a true appreciation of its power and dynamism.     The intellectual acknowledgement transmutes into an intuitive appreciation.       The Sun, which is many, many orders of magnitude grander than the Big Apple, will forever remain outside our intuition.     

So, too, for that matter will even the comparatively teeny motes of Earth and the moon remain unfathomable.   It might not be remote -look down, there it is- but Earth's proportions are such that we'd need to ascend to a height of nearly ten miles to even notice the planet's curvature.   

As for the moon: although its distance from us varies, it never ventures closer to us than about 238,000 miles.  One could neatly line up 30 Earths within the space that separates Earth from its one natural satellite.       Though it might well appear as a silvered orb looming large just above the distant summit, it's actually a small dark world far removed from terra firma.        In fact, the moon is 400 times smaller than the Sun.   However, it also is nearly 400 times closer to us than our parent star.        Consequently, the Sun and moon appear equally sized from our perspective and so, on occasion, the latter can move directly in front of and entirely cover the former to produce a total solar eclipse, such as the one that will happen on April 8th.

For the next couple of months, we will be delving into every possible detail related to this event: the dynamics, the history, the math, mythology and other aspects.      As we proceed, however, we shouldn't forget that we're observing the chance alignment of celestial spheres; spheres of grand proportions located at unfathomable distances.          As with everything in life from people to oceans to clouds forms, we'll be reacting only to our thoughts about these worlds, not to the worlds themselves.       Provided however that we at least acknowledge that the celestial sphere remains the abode of the gods we'll begin to understand the true scope of the event we're preparing to observe.

On April Eclipse 2:   Just a Simple Syzygy