TERRESTRIAL OR
EARTH BASED TELESCOPES 
== 1 TERRESTRIAL TELESCOPES - EARTH BASED
>> 2 CELESTIAL TELESCOPES - SPACE BASED
MENU
- THE PRISM BINOCULARS
- THE MONOCULAR TELESCOPE
- GALILEI TELESCOPE
- NEWTON TELESCOPE
- CELESTRON REFLECTOR TELESCOPE
- DOBSONIAN REFLECTOR TELESCOPE
- LOOKING AT SUNSPOTS
- RADIO TELESCOPE DWINGELOO
- RADIO TELESCOPE ARRAY WESTERBORK
- EUROPEAN GIANT TELESCOPE
Below described instruments exist out off a number of
binoculars and diverse sorts of telescopes.
We can study several astronomical phenomena, such as the sunspots, mountains and
craters on the Moon, phases of Venus, sand storms on Mars, four large moons of Jupiter,
rings of Saturn, double stars, stars and nebulae in our galaxy, comets, etc.
Look at a far object, e.g. a tower of a church. To get a sharp image with this binocular, you have to adjust the distance between the objective (object glass) and ocular (eyeglass) via middle rings.
The binoculars consists of a pair telescopes. The telescope is a Dutch invention made by two men in Middelbug in the Netherlands, namely Jansen and Lippershey (1608). This telescope was for Galilei the example for the construction of the first astronomical telescope (1609).
TECHNICAL DATA.
The represented binocular magnifies 10 times and has an objective with a diameter of 50 mm.
The field of vision of this binocular is 122. The field of vision is the number of meters, that you see around an object at a distance of 1 km of this object.
We calculate the illumination according to the formula: illumination = (diameter objective / magnification)². This binocular has a illumination of (50/10)² = 25.
By means of two light inverting prisms the image is represented for the eye in a
correct manner, for what concerns the objects at left and right, respectively above and
under in the picture.
Dutch => English
oculair => ocular
objectief => objective
de prismakijker => the binocular
Back to MENU
THE MONOCULAR TELESCOPE 20 x 50 mm.
Also named pirate spyglass, loved by one eyed pirate captains. Pull out the tube to full length and get a sharp image of a far object with the eyepiece ring.
With his by himself designed sort like telescope, which had a magnification of 30 x, Galilei discovered, except the mountains and valleys on the Moon, the sunspots and the four large moons of Jupiter, also that Venus as well as the Moon show phases and something particular (the ring) at Saturn. Galilei also discovered that in the telescope the galaxy dissolves itself in thousands of stars.
TECHNICAL DATA.
The represented telescope magnifies twenty times and has an objective with a diameter of 50 mm.
We calculate the illumination according to the formula: illumination = (diameter objective / magnification)². This telescope has a illumination of (50:20)² = 6.25.
Dutch
=> English
objectief => objective
oculair => ocular
Back to MENU
THE GALILEI TELESCOPE.
The design of this telescope is of Galileo Galilei (1564-1642). The refractor telescope consists out off an object glass (objective) and an eye glass (ocular) mounted in a tube. The picture formed by the object glass is examined with the eye glass, which works as a magnifying glass.
The astronomical telescope has an altazimuth mounting on a tripod, this means that it can be turned in an horizontal and vertical plane and for this reason also is extremely suitably for terrestrial vies of nature and the urban panorama.
Kepler improved the astronomical refractor telescope of Galilei by adding extra's, as a result of which measurements became more precise. On the basis of these measurements he reached the conclusion, that the planets move in elliptic and not in circular orbits around the sun.
TECHNICAL DATA.
The forming of the picture is based on refraction of light in lenses, therefore also the name refractor telescope.
The diameter of the objective of the represented amateur telescope is 50 mm. The length of the telescope is determinated by the focal distance of the objective and is 600 mm. More exactly said, it is the sum of the focal distances of objective and ocular.
The magnification is equal to the proportion of the focal distances of objective and ocular. With an ocular of 20 mm, resp. 6 mm we reach an enlarging of 30x, resp. 100x.
Close to the ocular is placed an inverting prism, as a result of which we can examine the erect image of objects outside the tube of the telescope.
 |
Dutch => English --------------------- oog => eye oculair => ocular objectief => objective licht => light |
Back to MENU
THE NEWTON TELESCOPE.
This reflection telescope has been designed by Sir Isaac Newton (1643-1727). The picture formed by the hollow mirror (objective) is examined by the eye glass (ocular), which works as a magnifying glass. The astronomical telescope has an equatorial mounting and as a result, it can be turned in the equator plane and an meridian plane of our earth. For this reason the telescope is extremely suitable to follow the daily celestial movements of the stars and less suitable for terrestrial observations.
Newton constructed the first mirror
or reflection telescope, which made possible a considerable larger aperture and as a
result a larger light receiving capacity. The refraction telescope of Galilei and the
reflection telescope of Newton, eventually extended with an Huygens ocular, still serve as
a main point for the construction of astronomical telescopes.
Also the laws of Kepler and Newton form still the first mental luggage of each
astronomer.
TECHNICAL DATA.
The forming of the picture is based here also on reflection in an hollow mirror, therefore also the name reflector telescope.
The diameter of the mirror of the represented amateur telescope amounts 114 mm. The focal distance of the mirror is 900 mm. With an eyepiece of 20 mm, resp. 6 mm we reach a magnification of 45x, resp. 150x. Close to the eyepiece is placed a flat mirror, which makes an angle of 45 degrees with the telescope axis, as a result of which the inverted image can be examined of the objects outside the tube of the telescope.
 |
Dutch => English --------------------- oog => eye oculair => ocular objectief => objective licht => light spiegel => mirror |
Back to MENU
CELESTRON
REFFLECTOR TELESCOPE
 |
Celestron NexStar 114 SLT Telescope Using Celestron's patented SkyAlign, simply input the date, time and location into the hand control then slew the telescope to any three bright celestial objects in the sky. And that's it - alignment so easy it's hard to believe! You'll spend your evening observing, not aligning your telescope!
|
For more of these instruments visit Binoculars.com US and Telescopes.com US or Telescopen NL.
Back to MENU
 |
LightBridge Truss-Tube Dobsonian - Deluxe It's not just a big telescope. It's a big telescope that goes anywhere. New LightBridge Truss-Dobs from Meade take down and set up quickly, so you can take one of these massive windows on the universe out to your favorite dark sky location with ease. LightBridge Dobs gie you high quality Meade optics, premium components and ultra portability all for about the same price as an ordinary tube Dobsonian. So get a LightBridge Truss-Dob and prepare to cross the universe. |
For more of these instruments visit Binoculars.com US, Telescopes.com US or Telescopen NL.
Back to MENU
The blindness of Galilei on later age is attributed to the fact, that he studied the sun with its telescope with naked eye. The ultraviolet radiation of the sun is to a great extent harmful for the retina of the human eye. Working with filters for sunlight at modern larger amateur telescopes is also discouraged, because these filters can crack by the heat of the joined sun rays (especially at high altitude of the sun) and the observer can loose an eye. More safely it is to make a image of the sun on a screen behind the eyepiece outside the telescope. Also we cannot use the viewfinder on the telescope, but the shade of this. We make this shade as small as possible, when we point the telescope to the sun.
You can also buy a solarscope to study the sun.
Back to MENU
This
Dutch radio
telescope was once world-famous with a single dish with a diameter of 25 meters, and
at that time also the largest in the world. Construction started in 1954, the telescope
was completed in 1956. It is no longer in operation as of 2000. Since 2007, it is
officially a national Dutch industrial heritage monument. The author of this web page
worked as student at this observatory in the sixties.
With this telescope was determined for the first time the detailed structure of the spiral structure of our galaxy. Radio waves (with wave-length 21 cm) emitted by hydrogen clouds in the spiral arms of our milky way were detected and a detailed map of the spiral arms could be made for as far as visible on the northern hemisphere. Australian radio telescopes completed the map later for the southern hemisphere.
Click with your mouse on the picture for a larger view.
Back to MENUWESTERBORK RADIO TELESCOPE ARRAY
This Dutch radio observatory, one of the largest in the world, is an
honorable successor of radio observatory Dwingeloo. The observatory has an array of many
connected dishes for the detection of radio waves from outer space. The dishes have all
the same diameter as the classic Dutch radio telescope in Dwingeloo and are very suited to
detect radio emission from hydrogen clouds in the 21 cm region, also for far away
galaxies. .
There is an array of fourteen parabolic dishes, all connected via electronic cables. Some of the dishes are movable on railroads over a distance till 3 kilometers. The measurements are collected by a computer and incorporated to make maps, in contrary to the classic Dwingeloo telescope build in a time when digital computers were hardly known in our world.
Click with your mouse on the picture for a larger view.
Back to MENU
ESO VERY LARGE
TELESCOPE ARRAY (VLT)
The European giant telescope (VLT) in Chile
is at present the largest and most modern optical telescope in the world for visible light and consists of four large mirror telescopes (each 8.2 meters in diameter), which are at present fully in operation.The separate telescope entities have been linked to each other in a similar manner as our Dutch Westerbork radio telescopes, on this way to produce a common image, what is much clearer and sharper than the image of each entity separate.
The telescopes have Indian names, namely Antu (Sun), Kuyen (Moon), Melipal (Soutern Cross) and Yepun (Sirius).
Click with your mouse on the picture right for a larger view.
Click with your mouse on the picture above for a larger
one (© ESO)
== 1 TERRESTRIAL TELESCOPES - EARTH BASED
>> 2 CELESTIAL TELESCOPES - SPACE BASED
