Mathematics of Telescopes

Missing Figures

A Brief History of Telescopes

Although telescopes has been around for several hundreds of years, there has been great discrepancy as to who invented it first. Here is one authors opinion. Lippershey was a Dutch spectacle marker during the early 17th century (approximately 1600). He was one of the first who created the "looker" (now called telescope) by placing two pieces of lenses together. The discovery that placing lenses together can magnify images were made by children who took Lippershey's spectacles and looked at a distant church tower.

One of the most influential scientist associated with the telescope has to be Galileo. He took the design and reinvented the telescope into one of the first refractive telescopes we use to this day.

Galileo used this great invention to report astronomical facts such as the moon is cover with craters instead of being smooth, the Milky Way is composed of millions of stars, and Jupiter have four moons. Perhaps the most famous discovery is the Earth revolves around the Sun and the Earth is not the center of the universe (even though he was discredited at the time).

Newton was also involved with telescopes. After his growing interest with light bending, he applied his knowledge of the reflecting and refracting properties of light and invented the first reflective telescopes. Newton's reflective telescopes vastly improve the clarity of images as well as escaping from chromatic abberration. In order to fully understand the concepts and ideas of how a telescopes work, some knowledge of simple optics are required.

Some Simple Optics

Refraction

Refraction occurs when light travels from one medium crosses a boundary and enters another medium of different properties. For example, light traveling from air to water. The amount of refraction (or bending) can be calculated using Snell's Law.

Refractor

How Refractor Telescopes Work

The principle behind the refractive telescopes is the use of two glass lenses (objective lens and eyepiece lens) to gather and bend parallel light rays in a certain way so that the image fits the size of the eye's pupil. Light rays is gather through the opening of the telescope called the aperture and passes through the objective lens and refracts onto a single point called the focal point. From there the light rays continue the same direction until it hits the eyepiece lens which also refract the light back into parallel rays. During the process, the image that enters our eyes is actually reverse of the original image and magnified because the size in which we preceive the image.