Astronomical Instruments

 

 

Why are instruments necessary for astronomical observations?

With our sense we can feel only light and heat from the heavenly bodies and for that too, we need instruments to accurately measure them. Other forms of energy such as X-rays, microwaves, gamma rays, etc., present in the Universe cannot be detected without instruments.

What instruments are used to detect the faint light from heavenly bodies?

Heavenly bodies faintly visible to the naked eye can be seen through telescopes. For observing very faint objects, telescopes of very high resolving power are used which can collect more light than the unaided eye.

 

 

 

What are the different designs of telescopes?

Mirrors that use lenses are known as refractor telescopes and those of reflector telescopes are Newtonian, Cassegrain, Herschelian, Gregorian, Conde and Schmidt designs. The refractor telescope has no major design variations.

 

 

 

 

 

 

 

 

 

What are the main components of a telescope?

Telescopes are optical instruments which make distant objects appear closer. The size of the image depends on the magnifying power of the telescope. The two main components of a telescope are: the “Eyepiece” through which one looks and the “Objective” which receives the light from the distant object.

The objective in a refracting telescope is a lens and in a reflecting telescope it is concave mirror. The eyepiece is always a lens.

 

 

How does a telescope magnify objects?

The objective of the telescope converges the light falling on it to a point called the focal point. The distance from the objective at which the light converges at the focal point called the focal length.

How precisely are large lenses and mirrors of astronomical telescopes made?

Large lenses and mirrors for astronomical telescopes are made to precision levels of one ten thousandth of a millimeter and checked by a ruby laser that can detect microscopic flaws. For example a 4000 mm primary mirror is made from a single 25 tonne block of glass that is carefully polished for three years during which its weight reduces to 17 tonnes.