The Sun's Heartbeat: And Other Stories from the Life of the Star That Powers Our Planet
“The sun has a heartbeat . . . is in fact a third generation star, . . . [and] The fate of our sun at the very end will not be a supernova, but . . . you’ll just have to read this fascinating book yourself!”
The sun has a heartbeat in which the sun, in 11-year cycles, alters both its appearance and energy output. The sun also reverses its magnetic polarity every 22 years. Everything about the sun is amazing. That the sun is bright may be obvious, but that the sun loses 4 million tons of mass per second may be less so. The sun emits lots of energy, including ultraviolet, light, and heat. Three percent of the sun’s energy is converted to neutrinos, and while most of the light given off by the sun is green, green plants reflect green, not absorb it. Green plants absorb blue and red.
“Stars are impossibly distant dots but this one is right here, offering its secrets, as deep as can be in exquisite detail,” says Bob Berman. How many of your friends know that a government panel has issued a warning that a future solar storm could destroy our nation’s power grid?
In relation to the rest of the universe, our sun is just another star. Stars are organized into 7 categories: O, B, A, F, K, G, M (by temperature—but the list has been alphabetically disordered by historical artifact). O and B class stars are the bluest and hottest. M class stars are the coolest and reddest. Our star is one of the middling G types. Mr. Berman explores not only the star categories but also how stars are created, the range of stars from suns to almost suns (those that no longer fuse hydrogen into helium), to double stars (which are quite common), and massive stars whose core fusion can run away and supernova. A supernova is a factory that creates all the elements heavier than iron.
Our sun is in fact a third generation star, a star that was created from a supernova of a star that was also created from a supernova. We know this from the spectrum of light our sun provides, which is a fingerprint of the material in the sun and also the material on the planets around it. The spectroscope is the instrument scientists use to identify elements in the Sun and in other stars. A spectroscope can also determine a star’s temperature, rotation, rotation of double stars, speed and motion in space, and even unseen companions.
There have been bizarre notions about the sun throughout history, such that it was inhabited and protected from heat by two layers of clouds, that it was made of ice, that it was Hell itself, that it got its fuel from comets. At least twice in the1700s astronomers traveled to distant locations to measure the transit of Venus across the face of the sun—first in 1761 then again in 1769—the goal being the calculation of the distance from the Earth to the Sun. The roundabout method comes from it being far easier to determine the relative distances of the planets’ orbits than absolute. Measuring Venus’ transit accurately would through geometric calculation yield the distance of the Earth to the sun. In the 1700s though, the transit measurements still weren’t accurate enough. Their efforts did lead to new discoveries however, that Venus had an atmosphere, and the discovery of diffraction of light; diffraction caused the apparent shape of Venus to change when it intersected the edge of the sun. The most accurate distance measurements of the Earth to Venus had to wait for the invention of radar.
Mr. Berman provides short biographies of scientists associated with discoveries about the sun, including Galileo, Fraunhoffer, Kirchoff, Bunsen, Zeeman, Maunder, and Eddy. Each chapter in The Sun’s Heartbeat is more or less independent and can be enjoyed as a stand-alone essay. The reader can pick and choose, skipping around, or even read chapters out of order according to interest. A sampling of the chapters provides entertaining explanations of the relationship of the sun to carbon dating, about infrared light and its relation to greenhouse gases, global warming and climate change, the effect of ionizing radiation on the ozone layer, on the constellations and signs of the Zodiac, on the human eye and color perception, and on solar eclipses, the aurora, and space weather.
Space weather is the invisible stuff that streams from the sun, which includes radiation that can impair GPS, and satellite and radio communication, disrupt satellites and cause failures in the power grid. Space weather and its ionizing radiation may be a greater determinant to the success or failure of man’s conquest of space than advances in technology.
The strength of Earth’s magnetic field varies with the conditions on the sun, in particular the number of the sun’s sunspots. A sunspot is where the sun’s magnetic field is strongest. It is seen as a dark spot because the field blocks material rising from the sun’s interior. Slower moving material is cooler, and cooler material is darker. When the sun’s magnetic field lines disconnect and reconnect, up to 20 million amps and 50,000 volts can be induced on Earth. This energy fuels the aurora but can also cause satellite failures, power transformer failures, and electrical grid failures. There are satellites in orbit now whose purpose is to measure and provide early warning of such events. Early warning allows airlines to rerouting paths to reduce the amount of X-rays given to pilots and passengers along high latitude routes, and this warning also provides enough time for astronauts in the International Space Station (ISS) to take shelter.
Note that Galileo wasn’t the first to record sunspots and the number of sunspots per year has widely varied over history as recorded by ancient cultures. There have also been multi-decades–long periods with no sunspot activity recorded at all. It also has also been noted that long periods of absence of sunspots correlate with periods of global cooling. Walter Maunder first theorized that the relationship between sunspots and variations in the Earth’s magnetic field through the mechanism of the solar wind. Jack Eddy followed Maunder in searching for the mechanism by which the solar cycle is connected to the Earth’s climate, and this is still an open topic of investigation. Sunspot activity has not only been tied to periods cooler climate on Earth but also the position and strength of the Gulf Stream, the thickness of the Earth’s atmosphere, the longevity of man-made satellites, the clarity of radio transmissions, and variations in the ozone layer.
The last chapter of The Sun’s Heartbeat addresses how the sun’s life will end. Approximately 1.1 billion years from now, the sun will radiate 10% more energy. The increased solar output will cause the oceans will evaporate. Eventually the Earth’s temperature will stabilize at about 710 degrees Fahrenheit. At this point the sun’s life as a star will be barely half over. The fate of our sun at the very end will not be a supernova, but . . . you’ll just have to read this fascinating book yourself!
The most difficult part in the responsibility of a critic is in relaying the bad along with the good. The author’s style here is particularly difficult to get used to. In the early chapters he generates solar facts in a stream-of-consciousness style, one after another, each being about the sun randomly and not thematically connected—perhaps with the intent of keeping it light, but instead generating the perception of being used as a stylistic tactic to hide a lack of depth. Mr. Berman’s point-of-view also tends toward flippancy, which sometimes falls to the level of insult. As examples, Mr. Berman refers to two scientists as “bearded buddies,” and makes the comparison that “Neutrinos are everywhere, like roaches in Rio.” As this flippancy is sprinkled throughout from beginning to end, the reader may wish that Mr. Berman’s editor had better sense—or greater control.