Harlow Shapley—A Profile in Astronomy

The Milky Way, at night a silver river;
Just look—the universe in stillness sleeps.
The night has decked the sky in constellations.
At such a moment one gets up and speaks
To time and history and to all creation!

Vladimir Mayakovsky Trans. James E. Falen

Harlow Shapley—A Profile in Astronomy

By Mark Sconce

Harlow Shapley


I wonder what the good folks of Pisa thought when they heard that their home-town boy found himself cross-wise with the Vatican? The year, 1633. Whatever they thought, the Church fathers found Galileo Galilei “vehemently suspect of heresy” and ordered him to renounce all his views about the Sun being the center of the universe and not the Earth—views supported by evidence gleaned from his new telescope of only three magnification.

Nevertheless, the fathers of the Roman Inquisition declared that his findings were contrary to Holy Scripture, a scripture based on Aristotle’s and Ptolemy’s ideas–ideas that had prevailed for nearly 1800 years. But the father of observational astronomy offered this: “I think that in the discussion of natural problems we ought to begin not with the Scriptures, but with experiments and demonstrations.” He spent the rest of his life under house arrest, lucky to have escaped torture in a dungeon.

Ideas sometimes take many, many years to sink in.* But sink in they do. Knowledge is acquired, accepted, and assimilated. Is there anyone today, excepting “flat- earthers,” who believes the sun and planets revolve around the earth? And does anyone of consequence really believe that astrology is better than astronomy in describing our place and condition in the universe? Telescopes made the difference of course; increasingly powerful telescopes changed everything. The Copernican Revolution was complete. It was a heliocentric universe after all (Helios, the Greek god of the Sun). Except for one thing. Polish astronomer, Nicolas Copernicus, and all his devotees believed that the Sun was the center of the universe. Ego-centric man had to be the center of something.

But by the end of the 19th century, astronomers, using vastly improved telescopes, recognized that the universe extended far beyond our solar system. Stephan Hawking wrote: “This change in worldview represented a profound transition in human thought: the beginning of our modern scientific understanding of the universe.” And let’s not forget the powerful intellectual achievements and influence of Isaac Newton, Albert Einstein and Harlow Shapley. Harlow Shapley?

Yes, my hero, Harlow Shapley, born on a farm in Nashville, Missouri in 1885, population 396 back in 2000. I wonder what the good folks in Nashville thought when they heard that their home-town boy had correctly estimated the size and structure of the Milky Way and our Sun’s position in it, an achievement, says Carl Sagan “… as important as the concept and reality of our Sun being at the center of our solar system.” In the 1910s, most interested observers believed that the Sun was near the center of the Milky Way. Shapley, using the new-built 60-inch telescope atop Pasadena’s Mount Wilson, made extensive observations between 1914 and 1919.

I would be hard put to accurately describe the method he used; I’ll just settle for “a parallax view.” Suffice it to say, he correctly placed our solar system cradled between two spiral arms at the edge of our spiral galaxy, our Milky Way, containing over three-hundred billion stars. He reckoned our Sun to be about 30,000 light years** from the center of the Milky Way, a great wheeling disc of stars and cosmic gas and dust majestically rotating once every 240 million years.

Imagine its shape as a vast wagon wheel, with its hub in the middle, cart-wheeling through the blackness of space. Rim to rim, Shapley reckoned its diameter to be 100,000 light years, and he was right. The bulge in the middle we now know to be a black hole four million times as massive as our sun and so dense that nothing escapes its gravitational pull, not even light. In this case, we’re lucky to be living on the edge.

(Before going further, let’s recall that a light year is not a measurement of time but of distance– enormous distance. We know that light travels at 186,000 miles per second {seven times around the Earth in one second!} Therefore, one light year equals about 6 trillion miles! Do the math…At last, something truly awesome!)

No hero is perfect; Dr. Harlow Shapley is no exception. His greatest error was concluding and defending in public the idea that the Milky Way was the extent of the universe. Other astronomers felt certain that other galaxies existed outside the Milky Way, one calling them “island universes.” Satisfaction was achieved when one of America’s most important astronomers, Edwin Hubble, weighed in with photographs he had taken with the new Hooker 100-inch telescope at Mount Wilson Observatory. Upon looking at the evidence, Shapley conceded saying, “Here is the (evidence) that destroyed my universe.”

In his role as Director of the Harvard College Observatory, he graciously encouraged Hubble to write a paper for a joint gathering of the premier American Astronomical Societies. Hubble’s findings went on to reshape fundamentally our view of the universe. How fitting that the space telescope, launched in 1990, whose images have thrilled and mesmerized the public, shall forever be known as the Hubble Space Telescope, the most sophisticated and productive scientific instrument in history.

With larger and more sophisticated telescopes came a better understanding of galaxies (most of them spirals like ours) beyond the Milky Way—thousands of them, then millions, then 100 billion and probably more containing on average 100 billion stars. Besides his trademark stellar count of “Billions and Billions,” Carl Sagan loved to spell out these numbers to emphasize the grandeur of it all: “One hundred thousand million billion stars.”

I hold in my hand, right reverently, too, Harlow Shapley’s 1958 book, Of Stars and Men signed by the author and gifted me by my father. The sub-title: The Human Response to an Expanding Universe. It’s one of those landmark books that shape the way we see things. Much like Silent Spring by Rachael Carson.

In the same way Galileo’s discoveries altered the way folks thought about their world and their place in it, Shapley details new discoveries to convince us that life is abundant and inevitable throughout the known universe. He proves his assertion statistically in the same way that strong circumstantial evidence convinces juries of guilt. His elegant writing rises to the occasion: “To establish, through statistical analysis the high probability of planets suitable for living organisms is not difficult. A statistical argument, in fact, is more convincing than would be a marginal observation.”

He goes on to discuss how adaptable and tenacious life is noting that some bacteria can even live in nuclear waste! What with billions of galaxies harboring billions of stars, many of them with “planetary potentialities,” it’s reasonable to conclude that some of those planets are habitable. (Over 4,000 exoplanets orbiting stars have since been discovered.) An ordinary star, our middle-aged Sun, on the edge of a typical spiral galaxy accomplished the creation of life on our planet “…through radiation to maintain the photochemical reactions that are the basis of plant and animal life.”

Every other star may be a Sun to someone. We now live in a galaxy that has more planets than stars, writes the National Geographic. The chances for life are, well, astronomical. Sagan again: “The universe is a pretty big place. If it’s just us, seems like an awful waste of space.”

Just knowing that life exists elsewhere is comforting. We will probably never meet because of the unimaginable distances that separate us. Nevertheless, finding life on another planet in another solar system, in or out of the Milky Way, would be “the most important news in human history,” declares Neil deGrasse Tyson. In the meantime, I recommend checking your library for the coffee-table book published by National Geographic titled HUBBLE—Imaging Space and Time. Here you will see images of the Cosmos unobstructed by earth’s distorting atmosphere. Through this new window on the observable universe, you will be rewarded by its unprecedented clarity and astonished by its immensity and majesty.

We, this people, on a small and lonely planet

Traveling through casual space

Past aloof stars, across the way of indifferent suns

To a destination where all signs tell us

It is possible and imperative that we learn

A brave and startling truth

Maya Angelou

* It took the Church nearly 350 years to admit that Galileo was correct after all…

**The distance is actually 28,000 light-years.


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Ojo Del Lago
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