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Many Skies

Many Skies: Alternative Histories of the Sun, Moon, Planets, and Stars

Copyright Date: 2005
Published by: Rutgers University Press
Pages: 216
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  • Book Info
    Many Skies
    Book Description:

    What if Earth had several moons or massive rings like Saturn? What if the Sun were but one star in a double-star or triple-star system? What if Earth were the only planet circling the Sun?These and other imaginative scenarios are the subject of Arthur Upgren's inventive bookMany Skies: Alternative Histories of the Sun, Moon, Planets, and Stars.Although the night sky as we know it seems eternal and inevitable, Upgren reminds us that, just as easily, it could have been very different.Had the solar sytem happened to be in the midst of a star cluster, we might have many more bright stars in the sky. Yet had it been located beyond the edge of the Milky Way galaxy, we might have no stars at all. If Venus or Mars had a moon as large as ours, we would be able to view it easily with the unaided eye. Given these or other alternative skies, what might Ptolemy or Copernicus have concluded about the center of the solar sytem and the Sun?This book not only examines the changes in science that these alternative solar, stellar, and galactic arrangements would have brought, it also explores the different theologies, astrologies, and methods of tracking time that would have developed to reflect them. Our perception of our surroundings, the number of gods we worship, the symbols we use in art and literature, even the way we form nations and empires are all closely tied to our particular (and accidental) placement in the universe.Many Skies, however, is not merely a fanciful play on what might have been. Upgren also explores the actual ways that human interferences such as light pollution are changing the night sky. Our atmosphere, he warns, will appear very different if we have belt of debris circling the globe and blotting out the stars, as will happen if advertisers one day pollute space with brilliant satellites displaying their products.From fanciful to foreboding, the scenarios inMany Skieswill both delight and inspire reflection, reminding us that ours is but one of many worldviews based on our experience of a universe that is as much a product of accident as it is of intention.

    eISBN: 978-0-8135-5356-6
    Subjects: Environmental Science, Astronomy

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-xii)
    (pp. 1-4)

    The sky we see is a familiar one, with few changes taking place over the course of a single human lifetime. Our current view results from a delicate balance between many factors, and changes in just a few of them would have given us a sky with a very different appearance. For example, what if we had more than one sun in the sky? Or more than one moon? In either case we would see a panorama transformed. Alternative history, in which the consequences of various “what ifs” are explored, has become very popular in recent years, at least within...


      (pp. 7-17)

      Our Moon, our eternal companion, our queen of the night, was the result of an accident. The Earth has been accompanied by its faithful moon almost since the formation of the solar system 4.6 billion years ago. We know that there was much more material flying around in those early days of the system than there is now; planet-sized chunks not ready to settle down into final, proper nearly round orbits revolving about the star in the middle of it all. Seemingly, these renegades flew about like loose cannons, but in fact, they, too, faithfully followed the laws of motion...

      (pp. 18-34)

      We assume here that the Sun is one of three stars in a system that closely resembles Alpha Centauri. We can still refer to it as the solar system, since our Sun is the largest, closest, and brightest of the lot. At a distance of only 4 light years, Alpha Centauri, seen in the deep southern sky as a single star, is the nearest of all stars and the third brightest in all the heavens, outshone only by Sirius and Canopus. But it really consists of the three stars that are closest to our solar system. The brightest of the...

      (pp. 35-38)

      The stellar magnitude system was developed, as far as anyone knows, by Hipparchus in the second century b.c. He produced a catalogue of the thousand brightest stars visible from his home city of Alexandria. Then he divided the stars into five classes of brightness, in which the first magnitude was reserved for about twenty of the brightest stars. The next brightest fifty or sixty he assigned to the second magnitude and so on through the third, fourth, and fifth magnitude, which comprised the faintest group of stars he could see. Then and now, the number of stars in each successive...

      (pp. 39-44)

      With the magnitude scale now explained in Chapter 3, we return to the triple-star solar system of Chapter 2.

      Proxima, also known as Alpha Centauri C, is one of the tiniest stars in nearby space, truly a 10-watt bulb among stars. It circles the pair composed of Helios and Osiris and their planets at a distance of some 13,000 astronomical units, about one-fifth of a light year. Its orbital period is not well known but must be of the order of one million years assuming, as we do here, a nearly circular orbit. This small star is a very faint...

      (pp. 45-51)

      The tower stands foursquare to the ocean and the wind. It is the pride of the city and the Empire. The city, Alexandria, the second largest in the Roman Empire after Rome itself, stretches for miles along the juncture between one of the mouths of the Nile River delta and the seacoast. It is an important granary and supply depot for lands surrounding the entire Mediterranean Sea. With its renowned library, housing scrolls with all of the knowledge of the world, the city is also its intellectual center.

      A young man gazes out over the harbor at the tower with...

    • 6 WE ARE ALONE
      (pp. 52-64)

      The Sun was setting on that bleak November day. In another hour the sky would be dark. On overcast nights we could see a modicum of light from natural and artificial illumination from the ground, but on clear nights the world and the sky are totally dark. No moons or planets act to illuminate the night because none exist. Only the stars remain. On occasion the Aurora Borealis and Aurora Australis shine near the magnetic north and south poles, respectively, in our upper atmosphere. Our spacecraft venture only into inner-earth orbits since there is no need to go farther into...


      (pp. 67-72)

      October always brings on the frigid days, the days when the Sun proceeds south to the point where it passes behind our great celestial ring system. The average daily temperature has dropped by 10 degrees just this week and we must get out our winter wear. Then in early November, the warmth returns, at least for a while. Like Saturn, we have this giant ring system girdling the Earth; by day the rings seem about as thick as feathery cirrus clouds, too thin to appear gray or any color other than brilliant white or even to cast shadows. But they...

      (pp. 73-81)

      What a sight the Moon and nearby Jupiter make when they appear close to each other in the evening sky before and after sunset. The Moon subtends an angle of half a degree, 3 times that of Jupiter, if that huge planet were in the orbit occupied by Venus, or about 10 times the area in angular terms. Balanced against this is the fact that the big planet, perpetually enshrouded in a thick atmosphere, has 5 to 6 times the albedo or reflecting power of the airless Moon and, being only 70 percent of the distance of the Earth and...

      (pp. 82-87)

      I looked upon the Martian surface. From a slight rise I could look straight along one of the “canals” that covered the planet when an intelligent race was assumed to have mounted a great effort to irrigate the equatorial regions from the melting polar caps during each hemisphere’s springtime. The Sun shone along the canal low in the deep southwestern sky; it would set in just a couple of hours. The borders of the canal were not even, but rough, with edges that just petered out onto the desert sands. Any apparent oasis was limited to the canal itself. In...

      (pp. 88-96)

      Halley’s comet is the only bright, spectacular comet that has a period of less than a few thousand years. What if its period were not about 76 years but only 5 or 10? Many comets move about that quickly, with Encke’s comet orbiting in only 3.3 years, the briefest of all. But, like the majority of comets, none of these are visible to the naked eye. They once had much longer periods but perturbations by the major planets, Jupiter in particular, disturbed them to the degree that their periods were vastly shortened. In fact, one comet, Shoemaker-Levy 9, was captured...

      (pp. 97-102)

      The Sun moves along the ecliptic by definition; it is the Sun’s path traced out in the sky. Since the ecliptic is inclined 23½º from the celestial equator, over the year the Sun moves no closer than 90º – 23½º = 66½º from either celestial pole. It does so in June when it is nearest the north celestial pole and again in December when closest to the south celestial pole. The Moon and all of the planets except tiny Pluto move in orbits whose planes are inclined 7 degrees or less from the plane of the ecliptic (see Fig. 10.1)....

      (pp. 103-108)

      Is Pluto a planet or is it something less? For years this question has been raised, discussed, and arbitrated again and again.

      Pluto’s 1930 discovery stemmed from the observations that neither Uranus nor Neptune followed the orbits that Newton’s cosmos, even with Einstein’s alterations, derived for them. Uranus strayed from the orbit it should have complied with, and this led directly to Neptune’s discovery. But later observations confirmed that neither followed their orbits, hence another planet must be out there somewhere. This led Percival Lowell to his search, which succeeded only after he died in 1915. The discovery in 1930...


      (pp. 111-116)

      Stars come in an assortment of colors. Not just any old color, as crayons do, but in the colors of the spectrum or rainbow. In Chapter 2, we noted that as stars get hotter they proceed in tint from red through orange, yellow, and white to blue. There are instances in the past in which observers have described the colors of some individual stars as mauve, lilac, garnet, and heliotrope, but no one today assigns to stars colors of such fancy; these tones are left for interior decorators. But the two extremes, red and blue, are very real, as anyone...

      (pp. 117-124)

      The sky changes slowly. With an occasional exception, alterations among the stars and constellations are orderly and require centuries for major changes to be detected. The supernovae that appeared in 1572 and 1604, known as Tycho’s Nova and Kepler’s Nova, were and would be today totally unanticipated. But the other changes, the motions of the Sun and planets, eclipses, transits, and occultations are now predicted well in advance, if only because they are all within the solar system. Predictions that involve objects belonging to the solar system are based on the high level of celestial mechanics that is possible when...

      (pp. 125-128)

      The summer triangle consists of three bright stars in three different constellations; they dominate the zenith area in the sky all summer long, and with Arcturus to the west and Antares in the deep south, they are the brightest stars visible at the time. All three are blue, with Vega easily the brightest at magnitude 0.0, while Altair and Deneb, at 0.8 and 1.3, respectively, are not much fainter. In the days before excessive light pollution in the cities and suburbs, they were seen along with their constellations rather easily, and the term “summer triangle” was rarely used to denote...

      (pp. 129-133)

      Stars are frequently bunched together into clusters; a cluster consists of stars gravitationally bound together, moving with a common parallel motion, and presumed to share a common origin. Clusters come in three different flavors, open clusters, globular clusters, and associations, with associations sometimes grouped together with the more prevalent open clusters into a single class.

      About a thousand open clusters are known and recognized as such in our galaxy. By recognized I mean that the cluster contains sufficient stars with a common motion to pass for a cluster and does not consist of just a few stars lying here and...

      (pp. 134-140)

      The southern end of the city and island of Miami Beach, known as South Beach, occupies the southern tip of that municipality and island. South Beach has graduated from a region of modest housing for older middle class people to an upscale neighborhood for swinging singles and others. After sunset, with palm trees swaying and clicking in the breeze in the balmy twilight, the city becomes awash in light, but here in South Beach it stays dark, devoid of outdoor lights, forbidden by municipal ordinance for a reason that becomes obvious as the dusky sky comes alive and the first...

      (pp. 141-146)

      Coordinate systems are devised to identify uniquely each and every point on a surface. They typically fix points on a plane, a left-right measure commonly labeled thex-coordinate and an up-down scale known as they-coordinate. These kinds of systems are called rectangular or, more commonly, Cartesian coordinate systems, named after René Descartes (1596–1650), the eminent French philosopher and mathematician. I suppose the best-known Cartesian system of coordinates is the following. The levels of theymeasure might be labeled 4, 14, 23, 34, 42, 50, 57, etc., and thexlines might be 1, 2, 3, etc., or,...

    • 19 WE ARE ALONE II
      (pp. 147-152)

      Ours is not the only galaxy; there are many others, billions altogether, scattered throughout the visible universe. Three of the nearest among them have been mentioned above; two of these are the Large and Small Magellanic Clouds, the two small satellite galaxies to our own Milky Way, about 180,000 light years from us. The third is the great spiral galaxy in Andromeda known also as Messier 31, or M31, a near twin to our own Milky Way in size and majesty. Lying almost 2 million light years off, it is the farthest object visible to the naked eye.

      Charles Messier...


      (pp. 155-158)

      Artificial satellites have been with us since October 1957, when the Soviet Union launched the firstSputnik, almost half a century ago now. Since that time satellites have become more numerous and sophisticated, but in one respect they have not changed. This is their visibility, their luminance from reflected sunlight as they spin about the world. Space is still mostly the province of governments and nonprofit institutions, although the corporate world has shared payloads on any number of them.

      Soon this will change. The expense of a launch into near-Earth orbit and the maintenance of a modest payload have dropped...

      (pp. 159-161)

      Celestial mechanics, the science of the determination and prediction of the positions of celestial objects, began with Johannes Kepler. He was the first to draw conclusions directly from observations—in his case those of Tycho Brahe. Kepler published his three laws of planetary motion, the first two in 1609 and the third ten years later. The first law, deduced from the motions of the planets, states that planets move in elliptical orbits with the Sun located at one focus. Every ellipse has two foci on opposite sides of the center and equidistant from it. All before Kepler, from Aristotle to...

      (pp. 162-174)

      The landscape was still with only the wind breaking the stony silence. The lake lay quiet and blue, not a restful blue but intense, of a piece with the surrounding desert, gray-white and rocky, not sandy such as Arab horsemen might ride over in Saharan melodramas like Sigmund Romberg’sDesert Song.Directly in front stood a stone house, now clearly abandoned. Any vegetation of the past was long gone; neither root nor branch nor twig passed for evidence of a former vertiginous existence.

      The scene reminded me of Lake Mono in central California, not far north of Death Valley and...

      (pp. 175-186)

      Earlier today we felt the ground shake, a great shudder of such violence that trees swayed back and forth and a few lost limbs or even fell over. Then nothing—all was quiet. But moments afterward great fireballs swooped across the sky, so bright that they could not only be seen in full daylight, but were even bright enough to cast shadows almost as intense as those cast by the Sun.

      It did not take us long to determine the cause of this display of fireworks; an asteroid about 10 kilometers (6 miles) in diameter had just struck the Earth....

    (pp. 187-188)
    (pp. 189-190)
  10. INDEX
    (pp. 191-198)
  11. Back Matter
    (pp. 199-199)