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TIME Magazine, February 9, 1948, p. 56
(cover story):


SCIENCE: Look Upward
    ...Palomar Mountain [Observatory] became a scientific necessity 18 years ago. With the 100-inch telescope on Mount Wilson, near Pasadena, Astronomer Edwin Powell Hubble had made one of the most flabbergasting discoveries science has ever made. The whole visible universe, Hubble's data told him, is apparently exploding. The matter in space appears to be flying apart for faster than the white-hot gases of detonating TNT.
    Hubble's discovery threw top-level science into confused arguments which are still raging... But every attempt to reason the theory away raised even more serious problems. Since Hubble had seen so much with the 100-inch telescope (whose range is 500 million light-years), the astronomers simply had to see still farther.
    This week the greatest telescope is almost ready. It is housed in a softly revolving dome 137 feet in diameter. The telescope weighs 500 tons, but is so exquisitely mounted that an electric motor not much bigger than an orange turns it on its bearings. Its 200-inch parabolic mirror gathers four times as much nebula light as Mount Wilson's 100-inch mirror. Palomar will see twice as far, and it may tell Hubble whether the universe is really exploding-- or whether even stranger things are happening.

    Out into Space. Even as an apprentice astronomer, Hubble concentrated on the nebulae-- the faint patches of light scattered among the stars [most of what were called "nebulae" in 1948 are now known as galaxies]... Hubble's first step when he started work on Mount Wilson Observatory in 1919 was to find out definitely how far away they were...
    Variable stars called Cepheids, discovered at Harvard, told him that the bright nebula called Messier 31 [the Andromeda galaxy] is 680,000 light years away. Messier 31 was therefore no mere part of the Milky Way galaxy (the star-congregation in which our sun is a fourth-rate star), but an isolated star-system far out in space and as big as our entire galaxy. Other, longer-ranged measuring sticks carried him farther on his march into space...
    By a complex statistical method Hubble proved, after years of work, that these dimmest glimmers were so far away that their light, speeding at 186,000 miles per second, took 500,000,000 years to reach Mount Wilson.
    His success in measuring the distance of dimmer and dimmer nebulae led to his crowning discovery-- the theory of the expanding universe.

    Universe in Flight. Astronomers have a speedometer to clock the motions of skittish heavenly bodies. They take spectrographs: photographs of the body's light spread out by a prism into a band of colors. If the band is "shifted toward the red" (i.e., if it is redder than normal), it shows that the body is moving away from the earth.
    Working with short, amiable spectrograph expert Milton Humason, Hubble studied the light of the distant nebulae. In every case he found a "red shift."* The farther off a nebula was, the faster it appeared to be rushing away, and the enormous speeds (thousands of miles per second) were new, strange and startling to astronomers.
    While Humason's spectrographs gradually improved, Hubble theorized until he came to a momentous conclusion: that the speed of recession of the nebulae is directly proportionate to their distance. This meant that each of the large units of matter in the universe (nebulae) [now called galaxies] is moving away from every other unit...
    ...Other men (including Einstein) had theorized about the universe, using their minds as telescopes. Hubble had evolved his theory by looking at the universe itself.
    The announcement of the exploding universe theory threw all grades of scientists-- from semi-mystic philosophers to earthy materialists-- into counterattack. Some critics could not believe that the nebulae move at such breakneck speed... Hubble and Humason have clocked a nebulae about 250 million light-years away that seems to be moving at 26,000 miles per second, more than one-eighth the speed of light...

    Hubble is glad to discuss such objections objectively. Even when an adversary uses that subtle, stylized rancor with which the more quarrelsome scientists conduct their controversies, he reacts with courtly tolerance.**
    One reason for his balance, and the imagination that helps his work so much, may be that he has never been completely immersed in astronomy, which can easily become an obsession. In summer he goes on long fishing trips, as far away as the Colorado Rockies. He belongs to the American Legion, takes part in "civic activities like a good Californian." He studies Chinese philosophy. He even knows movie people. Relations between the Mount Wilson astronomers and Hollywood have never been close... but Hubble has some friends (Aldous Huxley, Michael Arlen, Anita Loos) among the movie colony's intellectual set.
    ...Hubble, 6 ft. 2, strikingly handsome, and built like a heavyweight boxer (just what he was in college), was born in Marshfield, Mo. in 1889, and took his bachelor's degree in 1910 at the University of Chicago. He knew by then that he wanted to be an astronomer, but he took time out for a Rhodes scholarship and two years of law at Oxford...

    At Oxford, Hubble was charmed by English common law, which he still considers one of the great achievements of the human mind. He returned to the U.S. with a British accent (traces still remain), and became a member of the Kentucky bar. After one year of law practice (very dull), astronomy called with unmistakable loudness, and Hubble went to the Yerkes Observatory in Wisconsin to make friends with the sky.
    He had published one scientific paper and prepared for his doctorate examinations when the U.S. entered World War I. After enlisting in the Army, Hubble sat up all night, finishing his doctoral thesis, and took his examinations next morning. His Ph.D. from the University of Chicago caught up with him at Fort Sheridan, Ill.
    The tall young astronomer rose quickly from private to major. (Some of his friends still call him "Major.") After the war, astronomy called as loudly as ever, and Hubble took a long-promised job at Mount Wilson.

    Weary Waiting. Mount Wilson's 100-inch telescope showed him the exploding universe, but it raised more questions than it answered. Hubble's theory needed the 200-inch to prove or disprove conclusively. The Rockefeller Foundation had agreed to finance the great new instrument as long ago as 1928, but 500-ton telescopes cannot be ordered from a catalogue. The blank glass disc for the mirror was not cast until 1934. The whole project lagged.
    Meanwhile Hubble, Humason and their colleagues did the best they could with the 100-inch telescope, which had passed the peak of its effectiveness for many kinds of work. When Mount Wilson Observatory was founded in 1904, Pasadena was a quiet village, attractive to old ladies. Los Angeles was a distant, smallish city, not yet a great industrial center. But eventually, Los Angeles' suburbs sprawled over the whole mountain-surrounded plain. A strange, white, acrid haze (locally called "smog") rose from the city. Often the smog climbed over Mount Wilson, dimming the nebulae.

    The Deadly Lights. The lights, of all colors, which Los Angeles uses with a showman's abandon, flowed out like glittering lava toward Mount Wilson. The sky turned from velvety black to grey, fogging the sensitive photographic plates. The most striking feature in Humason's recent spectrographs is a strong black band (mercury light from the advertising signs of Los Angeles)...

    Slow Grind. As the city's lights crept toward Mount Wilson, the 200-inch telescope project also made progress. An ideal site had been found for it at Palomar Mountain, a 6,000-ft. plateau 90 miles to the south. No sea of lights would overwhelm the new observatory; the nearest sizable city, San Diego, is 50 miles away.***

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    In 1936, the glass disc arrived at the Pasadena optical shop of the California Institute of Technology to be ground and polished. The 20-ton blank was placed face up on a turntable. As it revolved slowly, a 48-inch disc set with block of abrasive was stroked mechanically back & forth from its edge across its center. The whole process was maddeningly tedious.
    The telescope frame progressed faster, but both it and the mirror were still unfinished when Pearl Harbor Day scattered the astronomers to those odd, essential posts that scientists fill in wartime. Hubble tried to get back his old job in the infantry, but was made Chief Ballistician at Aberdeen Proving Ground, Md.
    Astronomer-Ballistician Hubble came back from his second war with the Medal of Merit, and settled down. With his wife, the former Grace Burke, he lives in a charming mission-style house in San Marino, near Pasadena, on the edge of a steep geological fault which he thinks may be incubating an earthquake.
    His brother astronomers straggled back too. The massive telescope frame was completed quickly. At the optical shop, work went more slowly; the incredibly delicate task of polishing the mirror could not be hurried. The mirror had to be a paraboloid (a slightly deeper curve than a hollow sphere), accurate to two-millionths of an inch. Each grinding and polishing was done with fanatical watchfulness. Visitors were asked to remove their shoes, like pious worshipers at the door of a mosque; a single grain of tracked-in sand might scratch up the glass and spoil months of work.
    By August of last year, the worst was over. Dr. John A. Anderson, who had supervised the polishing, knew that he had succeeded. He set the great disc on edge for the final tests, which it passed with flying colors**** (TIME, Oct. 13). Seven weeks later, it was crated and trucked up Palomar Mountain.

    Hair Oil & Aluminum. The polished surface of the mirror was transparent glass, still to be covered with a reflecting film of aluminum. Before this could be done, the glass had to be cleaned perfectly. The trick was to cover the surface with a "monomolecular layer" (one molecule thick) of a fatty acid to keep dust off the glass. This process sounds formidably scientific, but in practice the glass was covered with a well-advertised brand of hair oil (essentially an emulsion of lanolin), and the excess wiped of carefully with special wool flannel.
    After the hair oil was removed by an electric blast of "ions," the great disc was "silvered" with vaporized aluminum. At last, the big eye was finished.

    The Pleasant Science. Long before this stage, Hubble and his colleagues had been driving up & down Palomar Mountain to admire their still blind telescope and its lovely setting...
    Palomar Mountain is more pleasant than most. The dormitory (called the "Monastery") is pleasant too. For day-sleeping astronomers, the bedrooms have soundproofed walls and doors and black window shades. The only intruders in this astronomical Eden are the woodpeckers that like to drill away at the Monastery's copper roof.

    Energy & Neutrons. All of Hubble's colleagues have projects for Palomar Mountain. Dr. Ira Bowen, Director of the Observatory, hopes to analyze the stars with superior spectrographs and find out what nuclear reactions are supplying the energy for their outpouring light. Dr. Bowen is a cautious man, but in the back of his head is a more daring project. No present-day star, he believes, has enough pressure or temperature to form the atoms of the heavier elements. Perhaps, he speculates, they were formed during the genesis of the exploding universe, two billion years or more ago, when all the matter in all the nebulae was concentrated in a single mass inconceivably hotter and denser than anything existing now.
    Astrophysicist Fred Zwicky of CalTech (who doubles in rocket propulsion) hopes to go gunning with the 200-inch for neutron stars and gravitational lenses. Various theories of stellar evolution tell how stars may be born and decline to stellar senility. Zwicky thinks that the last stage may be a star made up chiefly of neutrons. Since neutrons are very much denser than atoms, such stars might be only ten miles in diameter. Every cubic centimeter of their volume would weigh, Zwicky figures, about one million tons...

    Historic Night. Palomar's 200-inch telescope is all but complete now, with the big mirror in place. There is still much tinkering to be done. The mirror, slightly flexible, is supported by 36 complicated gadgets to keep it accurately in shape as the telescope changes its position. Each support contains 1,100 parts, and each will need expert adjustments before it works correctly. So will other mechanisms.
    But its creators are sure by now that all will be well. Soon, Hubble will take his first photograph of the depths of space. It will be a historic night-- an extra-clear night with the sky velvety black and the stars, though bright, twinkling hardly at all. Hubble will go into the observatory after dusk, rise to the big round telescope chamber in a push-button elevator.
    He will be carried up inside the the dome on a cleverly moving platform to the observer's cage, a cylindrical chamber, six feet in diameter, right in the muzzle of the telescopic tube. He will climb into the cage, sit down in a seat which moves as the telescope swings.
    Below him will lie the great mirror, like a pool of still black water dimly sprinkled with stars. Around him will flow the starlight, down to the mirror and up to the "prime focus" of the telescope... a rectangular hole in a tablelike structure in front of him.
    Hubble will know how to find the tiny bit of sky he wants to photograph. He will telephone instructions to an assistant down at the control desk; the massive telescope will swing almost silently. When Hubble is satisfied he will put a plate in the holder, watch through a microscope, and make careful minor adjustments while the scattered photons of nebula light (some of which have been traveling for a billion years) make their marks on the photosensitive emulsion...

*Dr. Vesto Slipher of Lowell Observatory measured, before Hubble, the slower speeds of nearer nebulae.
**Hubble would be the first to deny that all the credit for the expanding universe theory is his. Many others, from Harvard's Harlow Shapely to Belgium's Abbé Georges Lemaitre, have contributed.

***Humason alone is pessimistic. Thinking of his mercury-spoiled spectrographs, he says gloomily: "You don't know Southern California."

****The first thing the great eye reflected when set on edge was a row of pin-up girls on the wall of the optical shop.

By late 1948, it had been discovered that an error in the grinding & polishing of the Hale mirror made it "useless for serious astronomical purposes". See the Astronomy News page for a TIME article on this discovery. The mirror was dismounted in 1949, and repolished:

TIME Magazine, October 31, 1949, p. 64

SCIENCE: Exacting Mirror
    The world's most troublesome piece of glass, the 200-in. mirror or Palomar's Hale telescope, is back in shape again. Observatory Director Ira S. Bowen announced last week that the mirror, which was taken out for repolishing last May, has been tested on the stars and pronounced O.K. In places as much as 20 millionths of an inch of glass was polished off. Next step will be to cover the mirror with its shining coat of aluminum. Dr. Bowen hopes the big telescope will be hunting nebulae again by the first of the year.

Palomar After 50 Years

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