Book Review: Sun, Moon, Earth
One of the major natural events happening in your lifetime will total a little more than two minutes.
On August 21, 2017, if you are standing in the right place at the right time, day will turn to night. The Sun will turn black as the Moon’s shadow eats the Sun. The air will cool. Birds will grow silent. Stars will pop out around a ghostly corona of light.
Attend this event, and you will have experienced a rarity, something the majority of mankind never sees: a total solar eclipse.
Tyler Nordgren’s Sun, Moon, Earth, The History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets, Basic Books, 2016, will prepare you for the Great Eclipse of 2017.
More than a basic science book on solar and lunar eclipses, as the sub-title indicates, Nordgren’s concise and well-written book discusses the science of solar and lunar eclipses and how over centuries mankind’s understanding of his place in the universe grew out of observations of and discoveries connected to eclipses. As Nordgren writes, “In this book we will follow that story, from the shamans and astrologers who divined the patterns of eclipses and perfected their predictions to the philosophers and scientists who discovered the true causes of eclipses and used them to measure the world and explore the universe beyond.”
Nordgren, an astronomer and educator, accomplishes his goal admirably. He traces that story by beginning with some of the earliest evidence of mankind’s observations about eclipses. We learn about Native American petroglyphs in Chaco Culture, lunar eclipse counting in the Mayan Dresden Codex, the alignment of Nubian graves, and Chaldean calendars, and the role that eclipses played in divination for Chinese court astrologers. His examples are not long digressions of chapter length, or overwhelming in complexity. Each narrative or aside, like beads on a string, lead in nicely to his next point about eclipses.
This storyline of eclipses follows the ancient Greeks and some of their surprising deductions from logic and simple observation. The reader will learn about Ptolemy and his geocentric view of the Earth’s place in the solar system and Anaxagoras who understood that the shadow of the moon reveals that the Sun is farther away than the Moon. Nordgren covers the contributions of more familiar scientists in the history of Western science and their role in astronomy. He connects the discoveries of Kepler, Galileo, Newton, the largely unrecognized Alhazen, and Einstein, whose principles of relatively at last deciphered the puzzling, erratic transit of Mercury across the Sun, a puzzle that Newton math and a supposed mystery planet Vulcan couldn’t explain. In a fascinating last chapter, he leaves the reader with a lyrical and haunting image of a far-future Earth and Moon, where they slowly rotate around each other, the Moon neither rising nor setting, where a day on Earth will equal a lunar month.
Nordgren, throughout his book, informs his reader of the importance of the scientific method and how this method applied to eclipses, unlike religion or cultural superstitions, allowed humans to locate themselves in the universe. For example, Kepler, while working on the spacing and size of our solar system’s planets in the heliocentric model, arrived at his three laws of planetary motion by abandoning centuries of dogma and accepting evidence that elliptical orbits did not fit the inherited view of a perfect circular heaven.
Besides covering the history of eclipses, this book provides basic information for a lay reader about the mechanics of lunar and solar eclipses, data that will explain the rarity and mechanics of the 2017 solar eclipse. (Total solar eclipses occur at a single given point on Earth’s surface on an average of once in every 375 years.) Charts, illustrations, and pictures show how and why solar and lunar eclipses occur with clockwork regularity. He also provides a list of websites and other sources for those seeking more precise information about this summer’s eclipse and other topics related to it. Having read Nordgren’s book, the reader should become well- prepared on the mechanics of solar and lunar eclipses and know what to expect this summer when the shadow of the Moon eclipses the Sun. Nordgren gives a basic astronomical understanding of the math and science that astronomers use to predict precisely the location and timing of the Sun, Moon, and Earth’s alignments of shadows across space and time. (Nordgren discusses the safety aspects of viewing a solar eclipse and advises you not to waste the precious seconds of totality fiddling with a camera.)
Celestial mechanics aside, the August 21 solar eclipse is in Nordgren’s opinion much about the feeling of wonder and awe that totality brings. As Nordgren writes, “No other experience comes close to the multisensory strangeness of this most unnatural of natural events.”
Positioning yourself precisely in space-time for the August 21 solar eclipse is up to the reader, but before he experiences totality, he should consider aligning himself intellectually with the science and history of eclipses by reading Nordgren’s enjoyable and informative book.