who discovered it?
Johannes Kepler
Refracting telescope
The Keplerian telescope, invented by Johannes Kepler in 1611, is an improvement on Galileo's design. It uses a 
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 are there different type of this instrument? Yes, reflecting telescope, radio telescopes  and infrared telescopes who invented it? Hans Lippershey in what kind of research is the first type that you mentioned used? In astronomy as well as for terrestrial viewing are there any variations of this type of instrument? Yes the Keplerian telescope
wiki:19939008
Refracting telescope [SEP] Keplerian telescope
The Keplerian telescope, invented by Johannes Kepler in 1611, is an improvement on Galileo's design. It uses a convex lens as the eyepiece instead of Galileo's concave one. The advantage of this arrangement is that the rays of light emerging from the eyepiece are converging. This allows for a much wider field of view and greater eye relief, but the image for the viewer is inverted. Considerably higher magnifications can be reached with this design, but to overcome aberrations the simple objective lens needs to have a very high f-ratio (Johannes Hevelius built one with a focal length, and even longer tubeless "aerial telescopes" were constructed).