So they can get clearer images
This usually refers to a telescope that is actually located outside of the earths atmosphere. as opposed to a telescope designed to view outer space (which is all telescopes to my knowledge).
Usually, by using your eye sight, optical telescope, or radio telescope.
Urban places are usually located where there is a high population density. In Canada, an urban area must have at least a population of 1000 people. Other countries follow this sort of guidelines too, but the population differs.
The temperature and level of oxygen. High altitudes sometimes have more snow and low altitudes are usually drier.
A telescope eyepiece usually has 2 lenses in an astronomical telescope, and it is designed to give a magnified view of the virtual image produced at the focal point of the main lens.
It has a collection of mirrors and lenses - which direct the incoming image to the eyepiece, which is usually set at 90 degrees to the body of the telescope.
Several men laid claim to inventing the telescope, but the credit usually goes to Hans Lippershey, a Dutch lensmaker, in 1608.
Usually it's simply called a "solar telescope, but there are other names such as "helioscope" (specialising in sunspot observation).
Usually optical energy.
One advantage is that there is usually less turbulence at higher altitudes. I think because you are flying higher than those "pockets" of turbulence that you experience at lower altitudes.
The dates are in dispute. The year of the single-lens optical microscope is usually given as 1590 (remarkable, in that Zacharias Jannsen's birth year is sometime between 1580 and 1588), and the year of the telescope as 1608.
A parabolic mirror, usually. A spherical mirror is also sometimes used, but that requires additional corrections in other parts of the telescope.