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telescope

Definitions

  • Double-Carrying Telescopic Band-Mill
    Double-Carrying Telescopic Band-Mill
  • WordNet 3.6
    • v telescope make smaller or shorter "the novel was telescoped into a short play"
    • v telescope crush together or collapse "In the accident, the cars telescoped","my hiking sticks telescope and can be put into the backpack"
    • n telescope a magnifier of images of distant objects
    • ***

Additional illustrations & photos:

Lick Observatory telescope Lick Observatory telescope
Paris Exhibition telescope Paris Exhibition telescope

Webster's Revised Unabridged Dictionary
  • Interesting fact: It takes the Hubble telescope about 97 minutes to complete an orbit of the Earth. On average, the Hubble uses the equivilent amount of energy as 30 household light bulbs to complete an orbit.
    • n Telescope An optical instrument used in viewing distant objects, as the heavenly bodies.☞ A telescope assists the eye chiefly in two ways; first, by enlarging the visual angle under which a distant object is seen, and thus magnifying that object; and, secondly, by collecting, and conveying to the eye, a larger beam of light than would enter the naked organ, thus rendering objects distinct and visible which would otherwise be indistinct and or invisible. Its essential parts are the object glass, or concave mirror, which collects the beam of light, and forms an image of the object, and the eyeglass, which is a microscope, by which the image is magnified.
    • a Telescope Capable of being extended or compacted, like a telescope, by the sliding of joints or parts one within the other; telescopic; as, a telescope bag; telescope table, etc.; -- now more commonly replaced by the term telescoping.
    • Telescope To cause to come into collision, so as to telescope.
    • Telescope to shorten or abridge significantly; as, to telescope a whole semester's lectures into one week.
    • v. i Telescope To slide or pass one within another, after the manner of the sections of a small telescope or spyglass; to come into collision, as railway cars, in such a manner that one runs into another; to become compressed in the manner of a telescope, due to a collision or other force.
    • ***
Century Dictionary and Cyclopedia
  • Interesting fact: The Hubble telescope is so powerful that it is like pointing a beam of light at a dime that is two hundred miles away.
    • n telescope An optical instrument by means of which distant objects are made to appear nearer and larger. It originated in the first decade of the seventeenth century, apparently earliest in Holland; but Galileo in 1609 independently invented the form which bears his name, published it to the world, and was the first to apply the instrument to astronomical observation. The telescope consists essentially of two members: one, the objective, a large converging lens, or a concave mirror (technically speculum), which forms an optical image of the object; the other, the eyepiece, a small lens or combination of lenses, which magnifies this image. The optical parts are usually set in a tube, and this is so arranged that the distance between the objective and the eyepiece can be adjusted to give the most distinct vision. Telescopes are classed as refracting or reflecting, according as the objective is a lens or a speculum. The simple refracting telescope has for an objective a large convex lens, A (fig. 1), of long focus, while the eyepiece, B, is also a convex lens, but of short focus, the two being placed at a distance slightly less than the sum of their focal lengths. The “real” inverted image of the object formed at m by the object-glass is viewed by the magnifying lens B, the magnifying power being equal to the ratio between the focal lengths of the lenses A and B. With this form of instrument the object is seen inverted. In the Galilean telescope the eye-lens is concave instead of convex, and intercepts the rays from the objective before they reach the focus, so that the object is seen erect. But the field of view is very restricted, and this form of instrument now survives only in the operaglass. The simple refracting telescope in any of its forms is a very imperfect instrument, owing to the fact that rays of different color are not alike refrangible, the focus being nearer the lens for the blue rays than for the red. By making the telescope very long in proportion to its diameter, the injurious effect of this chromatic aberration can be greatly reduced, and about 1660 Huygens and Cassini used instruments more than 100 feet long in their observations upon Saturn. About the middle of the eighteenth century it was discovered in England that, by combining lenses of different kinds of glass, objectives could be made nearly free from chromatic aberration, and all the refracting telescopes now constructed have achromatic object-glasses of some form. The usual construction is a double-convex lens of crown-glass combined with a (nearly) planoconcave lens of flint-glass, the focal lengths of the two lenses being proportional to their dispersive powers, and the curves so chosen that the spherical aberration is corrected at the same time. But other forms are possible and even preferable. Fig. 2 shows some of those most used. For many years after the invention of the achromatic telescope it was impossible to obtain suitable glass for lenses of more than 5 inches in diameter. The discoveries of Guinand about 1800 partially relieved the difficulty, and from about 1870 to 1890 a considerable number of instruments have been made with apertures exceeding 2 feet—the largest so far being the great Lick telescope (fig. 3), of 36 inches diameter and 57 feet in length, the object-glass by Clark of Cambridge, Massachusetts. The next in size is the Pulkowa telescope, 30 inches in diameter, the object-glass also by Clark. The achromatic objective constructed of flint- and crown-glass is, however, by no means perfect, and cannot be made so while these kinds of glass are used. When the correction for the rays of mean wave-length in the spectrum is the best possible, the extreme rays—the red and violet—refuse to coincide with the others, so that the image of a bright object is surrounded by a purple halo, which renders it somewhat indistinct. This “secondary spectrum,” as it is called, is not very obtrusive in small instruments, but is a serious defect in large ones, and unfits the ordinary achromatic refractor for photography. For this purpose it is necessary to use an object-glass specially corrected for the violet rays, and therefore practically worthless for visual observations. But while it is impossible to secure a perfect color-correction with any lens composed of ordinary crown- and flint-glass, there is no reason why kinds of glass may not be invented which will render it possible; and since 1880 experiments, under the auspices of the German government, by Professor Abbé at Jena, appear to have resulted in at least partial success. Lenses as large as 12 inches in diameter have been made of the new glass. If large disks of this glass can be obtained sufficiently homogeneous, and not corrosible under exposure to the air, the art of telescope-making will immediately make enormous progress. The reflecting telescope was invented between 1660 and 1670. independently by Gregory and Newton, by the latter as the result of his discovery of the decomposition of light by refraction, which led him to conclude (erroneously) that the faults of the refracting telescope were necessarily incurable. There are four different forms of the instrument, differing only in the method by which the rays reflected by the concave speculum which forms the objective are brought to the eyepiece. In the Gregorian telescope (fig. 4) the rays reflected from the speculum are a second time reflected by a small concave mirror in the center of the tube, and just beyond the focus. The large mirror is perforated, and the eyepiece, placed behind the perforation, receives the rays thus twice reflected. In the Cassegrainian the construction is precisely similar, except that the small mirror is convex, and is placed within the focus; this shortens the instrument a little, but restricts the field of view. In both these forms the observer looks toward the object just as with a refractor. In the Newtonian form, which is the most used, the small mirror is plane, and set at an angle of 45°, so that the rays are reflected out at the side of the tube. Finally, in the front-view or Herschelian form the small mirror is dispensed with, the speculum being slightly tilted so as to throw the image to one side of the mouth of the tube. This saves the loss of light due to the second reflection, but involves some injury to the definition. Although the reflecting telescope is free from chromatic aberration, it seldom gives as perfect definition as an achromatic instrument, and is much more subject to atmospheric disturbance; the image also is less brilliant than that given by a refractor of the same aperture; but the speculum is much easier and less costly to construct than an achromatic object-glass of the same size, so that the largest telescopes ever made have been reflectors. At the head of the list stands the six-foot “leviathan” of Lord Rosse, erected in 1845, and still in use: it is of the Newtonian form. The five-foot silver-on-glass Cassegrainian reflector of Mr. Common, erected in 1889, stands next, and there are in existence a number of instruments with apertures of 3 and 4 feet. Herschel's great telescope, erected in 1789, but long since dismantled, was 48 inches in diameter and 40 feet long. The magnifying power of a telescope depends upon the ratio between the focal length of the object-glass and that of the eyepiece. (See eyepiece.) It can therefore be altered at pleasure by merely exchanging one eyepiece for another. As a rule, the highest power practically available, with the best object-glasses and under the best circumstances, is from 75 to 100 to every inch of aperture. The illuminating power is proportional, other things equal, to the area of the object-glass or the speculum; so that a telescope of 12 inches aperture ought to give four times as much light as one with a 6-inch lens. Practically, however, the larger lenses, on account of the increase in the thickness of the glass, do not reach their theoretical performance. Reflecting telescopes vary greatly in their light-gathering power. A Newtonian reflector with a silver-on-glass speculum freshly polished is not very greatly inferior in light to an achromatic of the same aperture; but as a rule a reflector in its ordinary working condition has only about half the light of the corresponding refractor. Small telescopes for terrestrial purposes are usually unmounted, but the tube is ordinarily made in several sections which slide into one another, reducing the length of the instrument, and making it more portable, as in the common spyglass. Larger telescopes are mounted upon stands of some kind, and the practical efficiency of the instrument depends greatly on the firmness and convenient arrangement of the stand. At present telescopes for astronomical use are almost always mounted equatorially—that is, the telescope-tube is attached to an axis, which itself is carried by another axis with its bearings so arranged that it points toward the pole. This principal axis is called the polar axis, and a clockwork is usually arranged to make it turn at the rate of one revolution in a sidereal day. When the telescope is once pointed at a celestial object, the clockwork will keep it apparently stationary in the field of view for any length of time. By the help also of graduated circles attached to the two axes it is easy to “set” the telescope so as to find any object whose right ascension and declination are known. Fig. 5 represents diagrammatically the equatorial of the usual German form.
    • n telescope [capitalized] Same as Telescopium.
    • n telescope A telescope with its tube completely filled with water. Such an instrument was used by Airy at Greenwich, about 1870, as part of a zenith-sector, in order to settle by observation certain questions relating to the aberration of light.
    • telescope To drive into one another like the movable joints or slides of a spy-glass: as, in the collision the forward cars were telescoped; to shut up or protrude like a jointed telescope.
    • telescope To move in the same manner as the slides of a pocket-telescope; especially, to run or be driven together so that the one partially enters the other: as, two of the carriages telescoped.
    • ***
Chambers's Twentieth Century Dictionary
  • Interesting fact: French astronomer Adrien Auzout had once considered building a telescope that was 1,000 feet long in the 1600s. He thought the magnification would be so great, he would see animals on the moon
    • n Telescope tel′e-skōp an optical instrument for viewing objects at a distance
    • v.t Telescope to drive together so that one thing, as a railway-carriage in a collision, slides into another like the movable joints of a spyglass
    • v.i Telescope to be forced into each other in such a way
    • ***

Quotations

  • Source Unknown
    Source Unknown
    “An atheist is a man who looks through a telescope and tries to explain all that he can't see.”
  • Source Unknown
    Source Unknown
    “Enthusiasm is a telescope that yanks the misty, distant future into the radiant, tangible present.”
  • Source Unknown
    Source Unknown
    “When looking for faults use a mirror, not a telescope”
  • Henry Ward Beecher
    Henry%20Ward%20Beecher
    “The soul without imagination is what an observatory would be without a telescope.”
  • Victor Hugo
    Victor%20Hugo
    “Where the telescope ends, the microscope begins. Which of the two has the grander view?”

Etymology

Webster's Revised Unabridged Dictionary
Gr. viewing afar, farseeing; far, far off + a watcher, akin to to view: cf. F. télescope,. See Telegraph, and -scope

Usage

In literature:

He had told his little son, aged five years, to look through the telescope.
"The Book of the Damned" by Charles Fort
Telescopic: arranged so that one portion of an organ or process may be drawn into another, like the joints of a telescope.
"Explanation of Terms Used in Entomology" by John. B. Smith
She found enjoyment, too, in peering through the great telescopes at the heavenly wonders.
"Debts of Honor" by Maurus Jókai
Shandon pointed his telescope in the direction indicated, and confirmed the pilot's announcement.
"The English at the North Pole" by Jules Verne
Preparation of Large Mirrors or Lenses for Telescopes.
"On Laboratory Arts" by Richard Threlfall
As they did so, Captain Dall put his telescope to his eye for a moment, wishing to scan closely the features of the chief.
"Sunk at Sea" by R.M. Ballantyne
Occasionally the doctor scanned the side of the mountain with his telescope.
"The Motor Maids at Sunrise Camp" by Katherine Stokes
He showed Myra its wonders through the telescope, discoursing on them with glee.
"Shining Ferry" by Sir Arthur Thomas Quiller-Couch
Oh, but am I not glad that General Zuroaga gave me that old telescope?
"Ahead of the Army" by W. O. Stoddard
He used the telescope and contemplated Walden on its screen.
"The Pirates of Ersatz" by Murray Leinster
With the help of the telescope we could certainly see some of the houses on shore.
"A Boy's Voyage Round the World" by The Son of Samuel Smiles
The telescope grasped the whole of the sun, and a considerable portion of the space surrounding it.
"Fragments of science, V. 1-2" by John Tyndall
Several thousand double stars are known altogether, while the motions of several hundreds of them have been detected with powerful telescopes.
"Aether and Gravitation" by William George Hooper
He no longer saw her sitting there by the telescope, calm, gracious, and beautiful.
"The World Peril of 1910" by George Griffith
Joe felt as a man might feel if the mirror of the greatest telescope on earth, in his care, had been smashed.
"Space Platform" by Murray Leinster
I here found my telescopic sight very useful for observing every movement while personally laying guns.
"With the Naval Brigade in Natal (1899-1900)" by Charles Richard Newdigate Burne
This observatory has no tower and no telescope.
"A Tour of the Missions" by Augustus Hopkins Strong
Telescope.# Same as above.
"Astronomical Instruments and Accessories" by Wm. Gaertner & Co.
Well, they had telescopes, didn't they?
"Eight Keys to Eden" by Mark Irvin Clifton
Finally I heard he was interested in the stars and owned a telescope.
"Child and Country" by Will Levington Comfort
***

In poetry:

How often have the critics, trained
To look upon the sky
Through telescopes securely chained,
Forgot the naked eye.
"A Criticism of Critics" by Robert Fuller Murray
"Alas! no present saint we find;
The white cymar gleams far behind,
Revealed in outline vague, sublime,
Through telescopic mists of time!
"The Chapel of the Hermits" by John Greenleaf Whittier
They brought him onions strung on ropes,
And cold boiled beef, and telescopes,
And balls of string, and shrimps, and guns,
And chops, and tacks, and hats, and buns.
"Pasha Bailey Ben" by William Schwenck Gilbert
Ah me! I see him on the cliff!
Farewell, farewell to hope,
If he should look this way, and if
He's got his telescope!
To whatsoever place I flee,
My odious rival follows me!
"Size And Tears" by Lewis Carroll
The old have had their days of hope,
They worked as through a telescope,
On years to come;—which came and fled,
But left sweet vestiges behind,
In Memory's heart of hearts enshrined,
The joys of love—the sainted dead.
"Pleasures of Memory" by John Bowring
Then she cried, Oh! father dear, come here and see the wreck,
See, here take the telescope, and you can inspect;
Oh! father, try and save them, and heaven will you bless;
But, my darling, no help can reach them in such a storm as this.
"Grace Darling or "The Wreck of the Forfarshire"" by William Topaz McGonagall

In news:

Euclid telescope to probe dark universe.
Despite the many observations by Hubble and other telescopes, astronomers are not sure what is causing the brightening.
Take a Tour Around the Telescope Array Where We're Searching for Extraterrestrial Intelligent Life.
Hubble telescope reveals farthest -ever view of universe.
Hubble telescope reveals farthest view into universe ever.
Department Of Energy/international Large Array Telescope Team).
The Gargantuan Telescope Designed to Find Life on Other Planets.
The Hubble Space Telescope, apparently.
Gezari (Johns Hopkins University), A Rest (Space Telescope Science Institute) and R.
Planet could be close enough to observe with conventional telescopes.
Hubble telescope finds Needle galaxy in celestial haystack.
I could see them at a distance, without a telescope.
DRILLERS began work last week on a revolutionary astronomical telescope that will operate three miles beneath the surface of the Pacific Ocean.
He had to set the clock to the exact time of local noon, as determined by his transit telescope.
Hubble's photo of Arp 274, the winner of a public contest to decide the space telescope's target for the International Year of Astronomy's "100 Hours of Astronomy" project.
***

In science:

The Whipple 10m telescope was the first IACT telescope to be operated (Cawley, 1990).
An Overview of The VERITAS Prototype Telescope And Camera
The observations have been made either at the 1.6 m LNA telescope in Brazil or with the 1.52 m ESO telescope in Chile.
An estimate of the time variation of the abundance gradient from planetary nebulae III. O, S, Ar, and Ne: A comparison of PN samples
Spectra from the ESO Very Large Telescope and ESO 3.6m Telescope of 24 objects in the sample.
Complete identification of the Parkes half-Jansky sample of GHz peaked spectrum radio galaxies
The 1.32 m telescope diameter and the 2.2 m distance between the telescope secondary and the back of the Offner relay define the overall size of the payload.
The Molecular Hydrogen Explorer H2EX
Experimental hard X–/gamma–ray astronomy is moving from direct sky-viewing telescopes to focusing telescopes.
Focusing of gamma-rays with Laue lenses: first results
NGC 247 was observed with the 1.3 m Warsaw telescope at LCO, the 2.2 m MPG/ESO telescope at La Silla Observatory and the 4.0 m Blanco telescope at CTIO.
The Araucaria Project: The Distance to the Sculptor Group Galaxy NGC 247 from Cepheid Variables Discovered in a Wide-Field
He finds a color difference between the two telescopes of δ(B − V ) = 0.12 mag at late times, when the second telescope began observing.
CfA3: 185 Type Ia Supernova Light Curves from the CfA
The Very Large Telescope Interferometer (VLTI) will soon be equipped with instruments able to combine between four and six telescopes.
An integrated optics beam combiner for the second generation VLTI instruments
At present, the instrument is fully working on the MMT telescope, and it is the first and only adaptive secondary mirror operating on a telescope.
Calibration of force actuators on an adaptive secondary prototype
In our telescoping representation, we de fine the state to be the field values at the telescoping surfaces.
Telescoping Recursive Representations and Estimation of Gauss-Markov Random Fields
We call ∂ T λ a telescoping surface since the telescoping representations we derive recurse these surfaces.
Telescoping Recursive Representations and Estimation of Gauss-Markov Random Fields
In deriving our telescoping representation for GMRFs on a unit disc in Section III, we saw that the recursions started at the boundary, which was the unit circle, and telescoped inwards on concentric circles and ultimately converged to the center of the unit disc.
Telescoping Recursive Representations and Estimation of Gauss-Markov Random Fields
In Fig 6(a)-(b), the telescoping surfaces are circles, however, we can also have other shapes for the telescoping surface.
Telescoping Recursive Representations and Estimation of Gauss-Markov Random Fields
Apart from the telescoping surfaces for a unit disc shown in Fig 6(a)-(d), we can de fine many more telescoping surfaces.
Telescoping Recursive Representations and Estimation of Gauss-Markov Random Fields
Telescoping Representations We now generalize the telescoping representation to GMRFs de fined on arbitrary domains.
Telescoping Recursive Representations and Estimation of Gauss-Markov Random Fields
***