Newtonian telescope
Newtonian Telescope
The Newtonian telescope is a type of reflecting telescope invented by the British scientist Sir Isaac Newton (1643-1727), using a parabolic primary mirror and a flat diagonal secondary mirror.
Newtonian Telescope
This entry contributed by Dana Romero
The Newtonian telescope is the simplest of the reflecting telescopes.
Newtonian Telescopes. Used for Lunar and planetary work should have focal ratios from f/6 to f/12 with small diameter secondary mirrors.
Newtonian telescope A reflecting telescope in which incoming light is intercepted before it reaches the prime focus and is deflected into an eyepiece at the side of the instrument.
Newtonian Telescope A reflecting telescope with a paraboloidal primary mirror, and a flat elliptical diagonal secondary mirror that directs the focal plane out of the side of the telescope tube.
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Newtonian telescope - (n.)
A type of reflecting telescope where the beam reflected by the primary mirror is reflected by a flat secondary mirror so that the focus falls to the side of the telescope tube.
New General Catalogue (NGC) - (n.) ...
Newtonian telescope (NASA SP-7, 1965) A reflecting telescope in which a small plane mirror reflects the convergent beam from the objective to an eyepiece at one side of the telescope.
Optical path of the Newtonian telescope.
The Lurie-Houghton design uses a similar arrangement of mirrors except the main or primary mirror has a spheroidal surface instead of a paraboloid.
See Newtonian telescope. Cassiopeia (abbr Cas, Cass) See constellation. catalogue = star catalogue. catalogue number The designation of a star by the name of a particular star catalogue and the number of the star in that catalogue.
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reflecting telescope ...
It was developed by John Dobson in the 1970s and was designed as a low-cost, easy-to-use mount for large Newtonian telescopes. Dobsonian mounts are generally constructed of wood and sit low to the ground.
Typically a Newtonian Telescope of 6' or 8" (15 or 20cm) aperture is considered a good starter project. Some widely available plans found on the Internet include instructions for building 6", 8", and 10" Newtonians.
Mirror making ...
As a rule of thumb, remember that an even number of reflections will give you an inverted (upside-down) image, such as a Newtonian telescope, since primary and secondary mirrors amount to two reflections.
Coma
This refers to the blurring of objects at the edge of the field of view, most common in short focal ratio Newtonian telescopes (at f/10 and longer, Newtonians are very well corrected for coma).
To combat instrument turbulence, most instruments are thermally stabilized or "cooled down" before use, telescope tubes are constructed to control or dissipate thermal instabilities, observers using Newtonian telescopes stand if possible down wind ...
Such "Newtonian telescopes" are still popular: the fact that the eyepiece is near the top of the instrument, not at the bottom, helps observers, but more important, in spite of the added accuracy requirement, ...
1669 - Isaac Newton constructs the first "pratical" reflecting telescope, the Newtonian telescope
1672 - Laurent Cassegrain designs the Cassegrain telescope
1675 - Royal Greenwich Observatory of England ...
For every action there is an equal and opposite reaction. Newton also improved the design of the refracting telescope (using an objective mirror, instead of a lens), and it is now called a Newtonian telescope.
Brewster (Ency. Brit. 8th ed. vol. xiv. p. 749) proposed a plan on a like principle, by dividing the plane mirror of a Newtonian telescope.
 See also: Telescope, Light, Field, Planet, Astronomy
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