CHAPTER LIII

ASTRONOMY No greater homage has ever been paid to the progress of American science than when the planning and supervision of the astronomical section of the new Encyclopaedia Britannica was entrusted to the late Prof. Simon Newcomb, who was also the only American save Benjamin Franklin ever elected an associate of the French Institute. His death occurred some time before the Britannica was completed, but he had already finished the articles which he had undertaken personally to contribute, and read a great number of the other articles which had, at his suggestion, been assigned to eminent astronomers in various parts of the world. His famous hand-book, _Popular Astronomy_, has been translated into all the European languages, and into Japanese as well; but the unlimited resources in the way of collaboration which the editorial organization of the Britannica put at his disposal, enabled him to assemble in these volumes a complete body of astronomical knowledge which is the greatest of his educational achievements. The making of a lens for a great telescope is the most difficult undertaking in all craftsmanship, and the mounting of the telescope itself a triumph of mechanical ingenuity. Yet the stars and planets have been guide-posts for the shepherd and the sailor throughout the ages, and have told the farmer when to sow and when to reap, and, even in our day, observations made by an amateur, through a common field-glass, have in more than one instance yielded results of serious value. [Sidenote: A Few Facts] Progress is from one point of view so slow that astronomers are now compiling data regarding fixed stars of which the motion cannot be deduced for centuries to come; yet some of the changes to be observed are so swift that solar prominences often rise at the rate of 350,000 miles an hour, and have been seen to rise to that height. The temperature of the sun’s envelope, 6000° C., greatly exceeds any that we can artificially create, and would convert into gas any substance we know; and for every unit of heat it sends to the earth, a hundred million other units, poured into space, are absolutely lost for any purposes of mechanical effect. Astronomy deals with objects so minute that even a shooting star evolving, as it passes through our atmosphere, so much light that we can trace its course with the naked eye, may be no larger than a grain of sand; deals, too, with objects of so shadowy a nature that the white clouds in our sky are, in comparison, solid blocks; and deals, again, with distances and surfaces so vast that numerical description fails to convey any impression but one of confusion. It is not easy to conceive, when we see a balloon in the air, the remainder that would exist if the bag, the car, and the cordage were all subtracted. There would be, until the gas mixed with the atmosphere, a sphere of gas. The stars, our sun included, seem to be masses of incandescent gas, possessing fairly definite boundaries, and not far from spherical in shape; the nebulae seem also to be masses of incandescent gas, irregular in form and having no clearly marked limits; even the nucleus of a comet is apparently not solid enough to be opaque; and as the four great planets also seem to be gaseous, it is probable that only the smaller bodies, like our earth, the moon, and Mars, are solid. To the rule that we can handle none of the matter that originates beyond the limits of our atmosphere, the meteorites supply an exception. Seventy years ago, a mass of stone, cold and invisible, flying through the aether of space at the rate of some hundred thousand miles an hour, entered our atmosphere, became so hot, as the air’s friction checked its speed, that bits of its surface, fused to crust, flicked off and floated in the air, leaving a shining trail; then as its speed was reduced to some three hundred miles an hour, cooled until it was no hotter than a laundress likes her iron to be. At Mhow, in India, as it made a dent in the earth, it killed a man—the only man known to history who has died so uncanny a death. But near Wold Cottage, in Yorkshire, England, thirty years before, another meteorite had fallen only ten yards from a labourer; and only thirty years ago another arrived on a Yorkshire railway line, forty yards from a gang of platelayers. The largest meteoric mass known weighs about fifty tons, but most of them seem to have split in the course of their journey; and at Hessle, a hundred thousand fragments spread, like grapeshot from a giant gun, over an area of some thirty square miles. See METEORITE (Vol. 18, p. 262). [Sidenote: Life on Mars] Although the closest scrutiny has not discovered in any meteorite a shred of life, even the lowest, we obtain, from another source, and by a different method of observation, evidence—as yet inconclusive,—that not only life, but intelligent life exists beyond our planet. As in respect of other astronomical problems, the Britannica is singularly clear, impartial and authoritative in its treatment of this question. The article MARS (Vol. 17, p. 761) was written by Professor Newcomb, but Professor Percival Lowell contributes a summary of the recent investigations and deductions relating to Mars with which his name is associated. In 1877, Schiaparelli, adopting the old belief now abandoned by all astronomers, that oceans occupied the darker-coloured regions of Mars, observed dark streaks connecting these dark patches, and, believing them to be strips of water, described them by the Italian word “canale,” by which he meant channels, or natural bodies of water. An absurd misconception of his meaning gave wide currency to the idea that these strips were artificial _canals_, a manifest impossibility, as they are many miles in width. No canal, properly so called, could be so wide, and no reservoir could conceivably be so extensive. There is, in the existence of such patches, even if they were bodies of water, as no one now believes them to be, not the slightest indication of excavation. In 1894, Professor Lowell, an American astronomer of great authority, established, for the special purpose of observing Mars, the Lowell Observatory at Flagstaff, in Arizona, 7,250 feet above sea level, in singularly clear, dry air, equipped with a twenty-four-inch telescope. This observatory unquestionably commands greater penetration than any other, and Professor Newcomb says that the work there upon Mars “has been continued with such care and assiduity that its results must take precedence of all others.” Professor Lowell’s first announcement that he had detected evidences of the existence of extensive artificial canals, which would of course absolutely prove Mars to be inhabited by intelligent creatures, was received with derision by many critics who jumped to the conclusion that he meant artificial canals many miles in width. Fuller statements from Professor Lowell showed that he believed Schiaparelli’s wide strips to be not water, _but areas of vegetation lying on each side of artificial irrigating canals of no extraordinary width_, by a network of which water is brought to, and distributed throughout, the temperate and equatorial zones of Mars from the extreme North and South, as the polar snow caps melt; and that this irrigation gives the rainless area a seasonal fertility, just as the melting of Abyssinian snows fecundates the distant valley of the lower Nile. These strips, according to Professor Lowell and other observers, are at one season of a bluish-green colour suggesting prosperous vegetation, then fade to a paler shade or in some places to a tawny brown. The strips are thousands of miles in length, perfectly straight. No one claims to have seen the artificial canals, but if there are areas of vegetation, they must be due to irrigation performed by waterways. If continued observations confirm the existence of these strips, it will become certain that they are not telescopic illusions, but the results of engineering operations on a scale unknown to our planet. The readings indicated in this chapter will yield a survey of this special field, as of all other fields of current research in astronomy, and give new interest to current investigations. A brief account of some of the principal astronomical articles is printed here in tabular form, and a fuller list, alphabetically arranged, follows this topical outline. _Topics for Reading_ _Article and Contributor_ Early Interest in the Sky. Astral theology—the “assumption of ASTROLOGY (Vol. 2, p. 795), and a close link between the BABYLONIAN AND ASSYRIAN RELIGION movements going on in the heavens (Vol. 3, p. 114), by Dr. Morris and occurrences on the earth.” Jastrow, author of _Religion of The history of astrology traced the Babylonians and Assyrians_. to ancient Babylonia (about 3000 B.C.). Story of the Constellations. A Map CONSTELLATION—with star-maps and of the Heavens. tables (Vol. 7, p. 11), by Charles Everitt, fellow Royal Astronomical Society. See also separate articles on the principal constellations and stars. Development of Astronomy. Scientific knowledge of the ancient ASTRONOMY, _History_ (Vol. 2, p. Chinese, Egyptians and 808), by Agnes M. Clerke, author Babylonians. Revolutionary cycle of _A Popular History of of the planets. Astronomy_. First conception of the earth as a PYTHAGORAS (Vol. 22, p. 699), by globe. “The harmony of the Dr. A. S. Pringle-Pattison, spheres.” Identification of author of _Man’s Place in the morning and evening stars (about Cosmos_, etc. 520 B.C.). The Greeks measure the earth by ERATOSTHENES OF ALEXANDRIA (Vol. 9, astronomical means (about 200 p. 733), by Sir Thomas Little B.C.). Heath, author of _Treatise on Conic Sections_. The first observatory. OBSERVATORY (Vol. 19, p. 954), by J. L. E. Dreyer, Director of Armagh Observatory. The first systematic astronomer, PTOLEMY, _Mathematics_ (Vol. 22, p. Ptolemy and his System (A.D. 620), by Prof. George J. Allman, 150). Queen’s, Galway; COPERNICUS (Vol. 7, p. 100), by Agnes M. Clerke. Revival of heliocentric theory KEPLER, JOHANN (Vol. 15, p. 749), (A.D. 1506–1512). by Agnes M. Clerke. Plan of Solar System realized. The GALILEO GALILEI (Vol. 11, p. 406), founder of descriptive astronomy by Agnes M. Clerke. (1564–1642). Newton’s contributions to astronomy NEWTON, SIR ISAAC (Vol. 19, p. and astronomical physics 586), by Henry M. Taylor, Fellow (1585–1586). of Trinity College, Cambridge. Continuation of Newton’s work. EULER, LEONHARD (Vol. 9, p. 887). Nebular hypothesis of Laplace NEBULAR THEORY (Vol. 19, p. 333), (1796). by Sir Robert S. Ball, author of _The Story of the Heavens_, etc. The New Astronomy. Work of Wollaston, Fraunhofer, ASTROPHYSICS (Vol. 2, p. 819), by Kirchoff, and Rowland in spectrum Dr. Simon Newcomb, late director analysis. National Observatory, Washington. Discoveries during recent eclipses. PHOTOGRAPHY, CELESTIAL (Vol. 21, p. Photographing the Heavens, 523), by Prof. H. H. Turner, Star-charts, etc. Oxford, author of _Modern Astronomy_, etc. Measuring light and heat from the PHOTOMETRY, _Celestial, or Stellar stars,—radio-micrometer. Photometry_ (Vol. 21, p. 530), by Dr. H. H. Turner, Oxford. New method of photographing the sun SPECTROHELIOGRAPH, illustrated and the results of this mode of (Vol. 25, p. 618), by Dr. George study. E. Hale, inventor of the spectroheliograph. Principles of Astronomy. How the positions and motions of ASTRONOMY, _Spherical or the heavenly bodies are defined. Geometrical Astronomy_ (Vol. 2, System of co-ordinates. p. 801), by Dr. Simon Newcomb. Distance of sun from earth the PARALLAX (Vol. 20, p. 760), by Dr. fundamental celestial Simon Newcomb. measurement. Methods of determining distances of STAR, _Distances and Parallaxes of stars. the Stars_ (Vol. 25, p. 789), by Arthur S. Eddington, Royal Observatory, Greenwich. Apparent motion of the heavenly ABERRATION, _Aberration of Light_ bodies. (Vol. 1, p. 54), by Dr. S. Otto Eppenstein, Zeiss Optical Works, Jena, Germany. Eclipses and their recurrence. List ECLIPSE (Vol. 8, p. 887), by Dr. of solar eclipses. Methods of Simon Newcomb. computing eclipses. Diameter of earth as an EARTH, FIGURE OF THE (Vol. 8, p. astronomical unit. Determination 801), by Alexander R. Clarke, of diameter and figure of earth. Ordnance Survey, and Prof. F. R. Helmert, University of Berlin. The Stars. The two Star-Streams. STAR (Vol. 25, p. 785), by Arthur Milky Way. Distribution of stars. S. Eddington, Royal Observatory, Greenwich. True nebulae. Constitution. How NEBULA, illustrated (Vol. 19, p. they differ from star-clusters. 332), by Arthur S. Eddington. Comets—origins and orbits. Physical COMET, illustrated (Vol. 6, p. constitution. List of periodic 759), by Dr. Simon Newcomb. comets. Shooting Stars. History of meteoric METEOR (Vol. 18, p. 260), by W. F. showers. Denning, formerly president, Liverpool Astronomical Society. Constitution of Shooting Stars. METEORITE (Vol. 18, p. 262), by Lazarus Fletcher, author of _Introduction to the Study of Meteorites_. General description of the Solar SOLAR SYSTEM (Vol. 25, p. 357), by System. Dr. Simon Newcomb. The photosphere, chromosphere and SUN, illustrated (Vol. 26, p. 85), corona, dimensions, temperature, by Dr. Ralph A. Sampson, and age of the sun, sun-spots. Astronomer Royal for Scotland. The vast envelope which surrounds ZODIACAL LIGHT (Vol. 28, p. 998), the sun. by Dr. Simon Newcomb. Are Northern Lights due to AURORA POLARIS, illustrated (Vol. emanations from the sun? 2, p. 934), by Dr. Charles Chree, president Physical Society of London. Opaque Bodies, members of the Solar PLANET, illustrated (Vol. 21, p. System. Their relation to each 714), and PLANETS, MINOR (Vol. other. Their spectra, atmosphere, 21, p. 717), both by Dr. Simon temperatures. First planetoid Newcomb. discovered (Jan. 1, 1801). Groupings of the planetoids. The smallest major planet. How it MERCURY (Vol. 18, p. 154), by Dr. presents the same face always to Simon Newcomb. the sun. Venus: Its peculiar rotation and VENUS (Vol. 27, p. 1013), by Dr. cloudy atmosphere. Has Venus a Simon Newcomb. satellite? The earth as a member of the solar EARTH (Vol. 8, p. 799). system. Our nearest neighbour. Is it MARS, illustrated (Vol. 17, p. inhabited? Similarity of physical 761), by Dr. Simon Newcomb, with conditions to those of the earth. a summary by Professor Lowell, of the observations at Flagstaff. The largest planet. Its belts, JUPITER, illustrated (Vol. 15, p. spots, markings and surface. Is 562), by W. F. Denning, formerly the great red spot a floating president, Liverpool Astronomical island? Society. The ringed planet. Physical SATURN (Vol. 24, p. 232), by Dr. constitution of rings. Simon Newcomb. Uranus: Its discovery, physical URANUS (Vol. 27, p. 788), by Dr. characteristics and satellites. Simon Newcomb. The outermost known planet. NEPTUNE (Vol. 19, p. 385), by Dr. Dimensions. Resemblance to Simon Newcomb. Uranus. Wonderful story of its discovery ADAMS, JOHN COUCH (Vol. 1, p. 177). (1845). LEVERRIER, U. J. J. (Vol. 16, p. 510), by Agnes M. Clerke, author of _A Popular History of Astronomy_. The moon. Its aspects, phases and MOON, illustrated (Vol. 18, p. constitution. Its mountains and 802), by Dr. Simon Newcomb. atmosphere. Development of Practical and Observational Astronomy. Current mode of star nomenclature ASTRONOMY, _History of Astronomy_ adopted (1603). First planetary (Vol. 2, p. 813), by Agnes M. transit observed by Gassendi Clerke, author of _A Popular (1631). History of Astronomy_. Astronomical Instruments. How co-ordinates used in ASTRONOMY, _Practical Astronomy_ astronomical research are (Vol. 2 p. 807), by Dr. Simon determined. Newcomb. Telescope: Discovery and history. TELESCOPE, illustrated (Vol. 26, p. Parts and mounting. Great 557), by Sir David Gill, formerly telescopes of the world. Astronomer Royal at the Cape of Good Hope, and H. Dennis Taylor, inventor of the Cooke Photographic Lens. The Transit Circle due to Tycho TRANSIT CIRCLE, illustrated (Vol. Brahe. Description and use. 27, p. 181), by J. L. E. Dreyer, Armagh Observatory, author of _Planetary Systems from Thales to Kepler_, etc. Measuring machines. Importance and MICROMETER, illustrated (Vol. 18, use in astronomy. p. 381), by Sir David Gill. Measuring the sun’s diameter. HELIOMETER, illustrated (Vol. 13, p. 224), by Sir David Gill. Old time instruments. “Nearly every ASTROLABE, illustrated (Vol. 2, p. one of the modern instruments 795), by Lady Huggins, author of used for the observatories of _Life and Work of G. P. Mazzini_. practical astronomy is part of the perfected astrolabe.” Complete list of observatories OBSERVATORY (Vol. 19, p. 953), by throughout the world, date of J. L. E. Dreyer, director Armagh foundation, their equipment and Observatory, author of _Planetary their specialized work. Systems from Thales to Kepler_. LIST OF ARTICLES IN THE ENCYCLOPAEDIA BRITANNICA ON ASTRONOMY Aberration Ablatitious Adams, John Couch Airy, Sir George B. Albategnius Albedo Albumazar (Abu-Maaschar) Algol Alidade Almacantar Altitude Amici, Giovanni B. Amplitude Andromeda Andronicus of Cyrrhus Anomaly Ansa Aphelion Apse and Apsides Aquarius Aquila Arcturus Argelander, F. W. A. Aries Aristarchus, of Samos Armilla Astrolabe Astrology Astronomy Astrophysics Auriga Azimuth Bailly, Jean S. Baily, Francis Bainbridge, John Bessel, Friedrich W. Bianchini, Francesco Binary System Biquintile Black Drop Bode, Johann Elert Boötes Bradley, James Brahe, Tycho Brisbane, Sir Thomas M. Brünnow, F. F. E. Calvisius, Sethus Campani-Alimenis, M. Cancer Canes Venatici Canis Major Capricornus Carrington, R. C. Cassini (family) Cassiopeia Celsius, Anders Centaurus Cepheus Cetus Chromosphere Clerke, Agnes Mary Colure Coma Berenices Comet Comet-Seeker Compression Conjunction Conon Constellation Copernicus, Nicolaus Corona Coronium Cosmic Culmination Cunitz, Maria Cycle Cygnus Cynosure Declination Dee, John Deferent Delambre, J. B. J. De la Rue, Warren Delisle, Joseph N. Delphinus Dial and Dialling Dick, Thomas Direct Motion Diurnal Motion Donati, Giovanni B. Draco Dupuis, Charles F. Earth Eccentric Eclipse Ecliptic Egress Ellipticity Elongation Encke, Johann Franz Ephemeris Epicycle Epoch Equation of the Centre Equation of Time Equator Equinox Eratosthenes of Alexandria Eridanus Eros Establishment of a Port Evection Facula Firmament Flamsteed, John Galileo, Galilei Gegenschein Gemini Geocentric Gould, B. A. Grant, Robert Halley, Edmund Hansen, Peter Andreas Hansteen, Christopher Heliacal Heliocentric Heliometer Hercules Herschel, Caroline L. Herschel, Sir F. W. Herschel, Sir J. F. W. Hevelius, Johann Hipparchus Horizon Horrocks, Jeremiah Hour Angle Huggins, Sir William Hydra Ideler, C. L. Immersion Inghirami, G. Ingress Invariable Plane Janssen, Pierre Jules C. Jupiter Kepler, Johann Lacaille, N. L. de Lalande, J. J. L. de Lamont, Johann von Latitude Lemonnier, Pierre C. Leo Leverrier, U. J. J. Libra Libration Lilly, William Lockyer, Sir J. Norman Longitude Longomontanus, C. S. Lunation Lyra Magellanic Clouds Mars Mayer, Johann Tobias Mercury Meridian Meteor Metonic Cycle Micrometer Mitcel, Ormsby M. Mitchell, Maria Möbius, August F. Moon Mouchez, A. E. B. Nadir Nebula Nebular Theory Neptune Newcomb, Simon Node Nostradamus Nutation Observatory Occultation Olbers, Heinrich W. M. Orbit Orion Parallax Penumbra Perigee Perihelion Perseus Phoebe Photography, Celestial Photometry, Celestial Piazzi, Giuseppe Pickering, E. C. Pisces Planet Planets, Minor Pleiades Pond, John Pons, Jean Louis Precession of the Equinoxes Prime Vertical Pritchard, Charles Proctor, Richard A. Ptolemy (Claudius) Quadrature Quetelet, L. A. Jacques Ramsden, Jesse Regiomontanus Reichenbach, G. von Repsold, Johann G. Retrograde Rheticus, or Rhaeticus Right Ascension Rittenhouse, David Robinson, J. T. R. Roemer, Ole Rosse, William Parsons, 3rd earl of Rümker, C. L. C. Sabine, Sir Edward Sacro Bosco, Johannes de (John Holywood) Sagitta Sagittarius Santini, Giovanni Satellite Saturn Schiaparelli, G. V. Schönfeld, Eduard Schröter, Johann H. Schumacher, H. C. Schwabe, Samuel H. Scorpio Secchi, Angelo Serpentarius or Ophiuchus Sextant Smyth, Charles Piazzi Solar System Solstice Somerville, Mary Sosigenes Spectroheliograph Star Stationary Stone, Edward Jones Struve, E. G. W. Sun Synodic Period Syzygy Taurus Telescope Terminator Three Bodies, Problem Tide Time, Measurement of Time, Standard Tisserand, F. F. Transit Circle, or Meridian Circle Trepidation Troughton, Edward Ulugh Beg Umbra Uranus Ursa Major Ursa Minor Venus Vertical Virgo Vulpecula et Anser Walker, Sears Cook Walther, Bernhard Zach, Baron von Zenith Zodiac Zodiacal Light Zöllner, J. K. F.