From the Sun to the Stars

The following sections are included:

• Dedication
• Contents
• What It's All About

The Sun: A glowing ball of heat and light that everyone appreciates, especially when missing it on a cloudy day, and no one dares look at except perhaps when rising or setting in the horizon murk or when behind sufficiently thick clouds. It's just too bright. But without its intense illumination, there would be no life, as nearly all the energy we live by ultimately comes from solar power, including that derived from fossil fuels. The seemingly simple solar facade hides a deeply buried nuclear engine that has allowed the Sun to glow at close to its current luminosity for nearly five billion years. And it has another five billion to go before it begins to die away, or perhaps better put, before it transforms itself into something quite different than it is today. That is a story for later, as is its place among its billions of siblings, seen at night as all the other stars sparkling against a blackened sky.

From our parochial perspective, the most important feature of the Sun is its set of planets, one of which is ours, the Earth. All shine by reflected sunlight. Traditionally, since the discovery of the outermost one in 1930, there have been nine to memorize, to learn about, Mercury through Pluto. However since the discovery of many more Pluto-like bodies in the far reaches of the Solar System, Pluto's been booted out of the pantheon, so the formal number has been cut to eight. But be careful saying “Pluto's not a planet anymore,” as children will assume that somebody blew it up. Pluto's still there! It's now seen as belonging more to a vast zone of orbiting debris, the “Kuiper Belt” (after Gerard Kuiper, 1905-1973), outside the orbit of Neptune, which has become the last planet standing. In a very real sense, the planets are the satellites, the “moons,” of the Sun, all born together four and a half billion years ago. While they play little role in the lives of the stars themselves (including that of the Sun), the planets are of great importance in illuminating the way in which the stars were (and are still being) formed. Moreover, the planets are obviously crucial to us, to humanity, as one of them provides a home for life. Perhaps the most powerful driving force in astronomy involves the answer to “Are we alone?” Are there others like us? To know, we first have to explore other stars to see if they too have planets, more significantly planets that might also support life (Chapter 8)…

“You can observe a lot by watching.” (Yogi Berra, who said he did not say all the things he said.) And watch we do, for thousands of years, both to enjoy and to comprehend the sky, its stars, its planets, its galaxies. Hardly trivial, pre-telescopic observation provided the foundation for Copernicanism, Kepler's Laws, and ultimately for part of Newton's great work on the rules of physics. But there are stringent limits as to what the unaided eye can accomplish. The breakthrough was made in 1609, when Galileo turned his telescope onto the sky. Though it had a lens only a couple inches across, it provided a powerful new technology that allowed him to reap vast rewards, which included evidence that Copernicus was not just dreaming, but correct.

In times past, the children of the aristocracy would take the grand tour of Europe to view the sights and help make them more worldly and sophisticated. Here we do the same with the sky, wherein we will more or less randomly romp among the stars and constellations to sample the celestial scenery, the idea really being to intrigue. We'll take various side excursions, after which we'll return to the main tour. In later chapters, we'll look at where the various celestial sights came from, how they fit together, what will happen to them, and ultimately what they mean to us.

Following the credit roll of " Chicken Run," an animated film based on "The Great Escape" (and after most of the audience has escaped as well), the chickens debate the philosophical, indeed biological, question: "Which came first, the chicken or the egg?" Transmogrifying the barnyard into the galaxy: Which now do we look at first, stars or the eggs that hatch them? Stars are born out of the dusty gases of the interstellar medium (ISM), the term for all the matter that lies in the vast spaces between them. And vast it is; the distance to the nearest star is 30 million times the solar diameter. Yet as sparsely scattered as they are, as they die stars profoundly affect the interstellar medium and help drive star birth. The result is a continuous cycle, though with important dropouts to be taken up later. We have to break in somewhere, so let's pick the ISM and the creation of stars. In the next chapters, we'll look more closely at the kinds of stars that come out of it and how they live their lives and finally expire…

Well, not really “infinite.” That would imply a cosmologically infinite Universe. Since there are only so many parameters you can use to define a star, if the Universe is infinite (for which there is no actual evidence) there must a duplicate of the Sun (or any other star), indeed an infinite number of them! (Credit “Cosmology,” R. R. Harrison). Here “infinite” is an apt metaphor for the immense array of stars that nature creates from the dark dusty clouds of interstellar space, of which the tour in Chapter 4 and the introduction to star formation in Chapter 5 give but a hint. (On the other hand we live in a quantum Universe where particles act like waves and cannot be pinned down in both velocity and position at the same time: the Heisenberg Uncertainty Principle. That could mean that even in an infinite Universe true replication is impossible.)…

While there are those who reject anthropomorphism in science, it remains a metaphoric, poetic way of expression that infuses astronomy. We speak of stars being born, of passing through youth, middle age, old age, of dying, as if they were sentient beings. Thus W. H. Auden's verse aside ("you can look it up"), in our hearts they can be friends that are with us so long as we, along with Whitman, walk the Earth.

Richard Proctor's daughter Mary (1862-1957) became the first woman science writer, communicating astronomy with excellence as did her father. She most famously authored "Stories of Starland" in 1895 for children.

The following sections is included:

• Index