اللغة الانجليزية

I'm very happy to work with these students 
1-Thamer Bander Al Rasheed
2-Hussien El Shahrani
3-Abdel Aziz Al Dehilan 
4-Abdel Majeed Khan
Inshaa Allah we will make a research about 
Day , Night , and seasons 

 Abdel Aziz Aldehilan has made a research about telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The first known practical telescopes were invented in the Netherlands at the beginning of the 17th century, using glass lenses. They found use in terrestrial applications and astronomy.
Within a few decades, the reflecting telescope was invented, which used mirrors. In the 20th century many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. The word telescope now refers to a wide range of instruments detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.

The word "telescope" (from the Ancient Greek τῆλε, tele "far" and σκοπεῖν, skopein "to look or see"; τηλεσκόπος, teleskopos "far-seeing") was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at theAccademia dei Lincei.[1][2][3] In the Starry Messenger, Galileo had used the term "perspicillum".

History

Main article: History of the telescope

The invention of the achromatic lens in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes. Reflecting telescopes, though not limited by the color problems seen in refractors, were hampered by the use of fast tarnishing speculum metal mirrors employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857,[9] and aluminized mirrors in 1932.[10] The maximum physical size limit for refracting telescopes is about 1 meter (40 inches), dictating that the vast majority of large optical researching telescopes built since the turn of the 20th century have been reflectors. The largest reflecting telescopes currently have objectives larger than 10 m (33 feet), and work is underway on several 30-40m designs.The idea that the objective, or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope.[7] The potential advantages of using parabolic mirrors—reduction of spherical aberration and no chromatic aberration—led to many proposed designs and several attempts to build reflecting telescopes.[8] In 1668, Isaac Newton built the first practical reflecting telescope, of a design which now bears his name, the Newtonian reflector.
The 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first purpose built radio telescope went into operation in 1937. Since then, a tremendous variety of complex astronomical instruments have been developed.

Types of telescope


The name "telescope" covers a wide range of instruments. Most detect electromagnetic radiation, but there are major differences in how astronomers must go about collecting light (electromagnetic radiation) in different frequency bands.

Telescopes may be classified by the wavelengths of light they detect:
Light Comparison
NameWavelengthFrequency (Hz)Photon Energy (eV)
Gamma rayless than 0.01 nmmore than 10 EHZ100 keV – 300+ GeVX
X-Ray0.01 to 10 nm30 PHz – 30 EHZ120 eV to 120 keVX
Ultraviolet10 nm – 400 nm30 EHZ – 790 THz3 eV to 124 eV
Visible390 nm – 750 nm790 THz – 405 THz1.7 eV – 3.3 eVX
Infrared750 nm – 1 mm405 THz – 300 GHz1.24 meV – 1.7 eVX
Microwave1 mm – 1 meter300 GHz – 300 MHz1.24 meV – 1.24 µeV
Radio1 mm – km300 GHz – 3 Hz1.24 meV – 12.4 feVX
As wavelengths become longer, it becomes easier to use antenna technology to interact with electromagnetic radiation (although it is possible to make very tiny antenna). The near-infrared can be handled much like visible light, however in the far-infrared and submillimetre range, telescopes can operate more like a radio telescope. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm (0.003 mm) to 2000 μm (2 mm), but uses a parabolic aluminum antenna.[11] On the other hand, the Spitzer Space Telescope, observing from about 3 μm (0.003 mm) to 180 μm (0.18 mm) uses a mirror (reflecting optics). Also using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe from about 0.2 μm (0.0002 mm) to 1.7 μm (0.0017 mm) (from ultra-violet to infrared light).[12]
At the photon energy of shorter wavelengths and higher frequency, fully reflecting optics rather than glancing-incident optics are used. Telescopes such as TRACE and SOHO use special mirrors to reflect Extreme ultraviolet, producing higher resolution and brighter images than otherwise possible. A larger aperture does not just mean that more light is collected, it also enables a finer angular resolution.
Telescopes may also be classified by location: ground telescope, space telescope, or flying telescope. They may also be classified by whether they are operated by professional astronomers or amateur astronomers. A vehicle or permanent campus containing one or more telescopes or other instruments is called an observatory.

Telescopic image from different telescope types



هناك 3 تعليقات:

  1. Unknown7 ديسمبر 2015 في 10:09 ص

    بارك الله فيك أستاذ صلاح موفقين ان شاء الله

    ردحذف
  2. Unknown8 ديسمبر 2015 في 10:51 م

    رائع أستاذ صلاح موفقين ان شاء الله

    ردحذف
  3. Unknown10 ديسمبر 2015 في 1:09 ص

    احب اشكر المنسق الرائع الاستاذ عبد رب النبي علي مساعدته لينا واستجابته وهذه والله ليست مجاملة
    جزاك الله خيرا وجزي الله الطلاب الرائين كل الخير

    ردحذف

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