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The first known practically functioning telescopes were the refracting telescopes were invented in the Netherlands in 1608, and were credited to three individuals: Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, and Jacob Metius of Alkmaar. Hans Lippershey is the earliest person documented to have applied for a patent for the device. These early refracting telescopes consisted of a convex objective lens and a concave eyepiece and the telescope simply slid inside itself to focus. In 1611, Johannes Kepler described how a telescope could be made with a convex objective and eyepiece lens, and by 1655 astronomers such as Christiaan Huygens were building powerful but extremely large and unwieldy Keplerian telescopes with compound eyepieces. By the year 1616, Niccoa Zucchi had designed the first reflecting telescope, but the design was impractical. In 1688, Sir Isaac Newton had solved the problems of Zucchia’s reflector by adding a small flat diagonal mirror to reflect the light to an eyepiece mounted on the side of the telescope. Newton built the first practical reflecting telescope, which is called Newtonian reflector. In 1704, Sir Issac Newton announced a new concept in telescope design whereby instead of glass lenses, a curved mirror was used to gather in light and reflect it back to a point of focus. This reflecting mirror acts like a light-collecting bucket: the bigger the bucket, the more light it can collect. The reflector telescope that Newton designed opened the door to magnifying objects millions of times – far beyond what could ever be obtained with a lens. Laurent Cassegrain in 1672 initiated the design of a reflector with a small convex secondary mirror to reflect light through a central hole in the main mirror. The achromatic lens, which greatly reduced color aberrations in objective lenses and allowed for shorter and more functional telescopes, first appeared in a 1733 telescope made by Chester Moore Hall, who did not publicize it. Five years later, John Dollond independently developed achromatic lenses and produced and marketed telescopes using them in commercial quantities. Some other important developments in reflecting telescopes were John Hadley's production of larger paraboloidal mirrors in 1721; the process of silvering glass mirrors introduced by Lon Foucault in 1857;[3] and the adoption of long lasting aluminized coatings on reflector mirrors in 1932. The 20th century saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first radio telescope went into operation in 1937. Since then, a tremendous variety of complex astronomical instruments have been developed.
A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The word 'telescope' (from the Greek tele = 'far' and skopein = 'to look or see') was coined in 1611 by the Greek mathematician Giovanni Demisiani.
Telescopes
by MyPie
The history of the telescope
3 main types of telescopes:
This type uses a series of lenses and mirrors that fold the light path and send it through to the primary mirror through a small hole. This allows the light to be magnified and focused for viewing. There are two types of Catadioptric telescopes - Schmidt-Cassegrain and Maksutov-Cassegrain. The Maksutov type has a concave and convex correcting lens where the light enters. The light hits the primary mirror, is sent back to the secondary mirror and finally sent to the opening in the back of the telescope.
The Newtonian Reflector uses a primary mirror that is concave. This mirror sends light to a flat mirror which reflects the light out a side opening and to the eyepiece where it is magnified and focused. Catadioptric telescopes are portable and easy to use, and good for deep space and planetary observation.
The traditional long-tube looking telescope. The Refractor uses lenses to bend light and this causes the rays to meet at a point on the other end of the telescope. They are magnified by the eyepiece for viewing. There is a large lens on the front of the Refractor, which is the objective lens. Refractor telescopes require little to no maintenance, and are excellent for planetary viewing. But they have color deviation in achromatic designs, and are not recommended for deep sky observation.
The Refractor Telescope
The Catadioptric Telescope
The Reflecting Telescope
By 1610, Galileo Galelei discovered four moons orbiting the planet Jupiter, sunspots, the phases of Venus, craters on the Moon, the rings of Saturn, and the stars of the Milky Way by using his refractor telescope.
Telescope maker William Herschel discovered Uranus and the sixth and seventh moons of Saturn between 1782 and 1789 with his reflecting telescope.
The National Aeronautics and Space Administration (NASA) and the European Space Agency have discovered gamma ray burst and faint stars by using the Hubble space telescope, which is an optical reflector.
Important discoveries made about our solar system and our universe by using telescope!
