are there different type of this instrument?
Yes, reflecting telescope, radio telescopes  and infrared telescopes
Telescope
The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. 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 capable of detecting different regions of the electromagnetic spectrum, and in some cases 
io and europa the inner two of jupiter's four largest moons They include also Ganymede, and Callisto what are these four moons collectively known as? The Galilean moons who discovered them? Galileo Galilei are these moons visible from earth? Yes through a telescope
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Telescope [SEP] Introduction
A telescope is an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects, or various devices used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. The first known practical telescopes were refracting telescopes invented in the Netherlands at the beginning of the 17th century, by using glass lenses. They were used for both terrestrial applications and astronomy. The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s.