Galileo telescope how does it work

And what has become of it today? Luckily, all of these are questions we are able to answer. Galileo had no diagrams to work from, and instead relied on his own system of trial and error to achieve the proper placement of the lenses.

Galileo knew that light from an object placed at a distance from a convex lens created an identical image on the opposite side of the lens. He also knew that if he used a concave lens, the object would appear on the same side of the lens where the object was located. If moved at a distance, it appeared larger than the object. In the late summer of , a new invention was all the rage in Europe — the spyglass. These low power telescopes were likely made by almost all advanced opticians, but the very first was credited to Hans Lippershey of Holland.

These primitive telescopes only magnified the view a few times over. Much like our modern times, the manufacturers were quickly trying to corner the market with their invention. When Galileo heard of this new optical instrument he set about engineering and making improved versions, with higher magnification.

Within a few years, he began grinding his own lenses and changing his arrays. As seen from the Earth, Venus goes through a full set of phases in a similar way to the Moon. However, because Venus appears so small, these are only visible through a telescope and Galileo was the first person to see them.

At point A in the diagram above, when Venus is between the Earth and the Sun, the sunlit part of Venus faces away from us making the planet almost invisible. The amount of the sunlit part of Venus we can see gets larger or waxes through to a crescent phase B , to a half Venus C and then to a full Venus at point D, when the whole sunlit side facing the Earth is illuminated.

It then gets smaller or wanes back to a half Venus E , then to a crescent F and then finally back to being almost invisible back at point A. As readers of a previous post will know, in , just before his death, Nicolas Copernicus had published the theory of heliocentrism which states that the planets orbit the Sun.

Indeed certain verses of the bible could be interpreted as supporting that viewpoint, such as Psalm However, the phases of Venus which Galileo had seen can only be explained by Venus orbiting the Sun. Therefore, Galileo concluded that the geocentric theory was incorrect. Unfortunately for Galileo, in the Catholic church declared heliocentrism to be heresy. Heliocentric books were banned and Galileo was ordered to refrain from holding, teaching or defending heliocentric ideas.

Galileo was kept under house arrest until his death in It also had a narrow field of view. In Johannes Kepler began investigations into the way that different combinations of lenses could work together to produce a magnified image.

Nowadays the Galilean telescope design is only used in low power binoculars. Keplerian and Galilean telescopes are both example of refractors where lenses are used to collect and focus light. Nowadays all large telescopes are reflectors where curved mirrors , rather than lenses, are used. Reflectors have a number of advantages. This happens in refractors because different colours of light are bent very slightly differently as they pass through the lens, which results in a blurred image.

Chromatic aberration can be overcome by using achromatic lenses, which consist of two or more lenses made out of different types of glass joined together to form a compound lens, but this is expensive and technically difficult when constructing larger lenses. The main advantage of reflectors is that it is much easier to produce a large mirror than a large lens.

A large lens many metres in diameters would be very thick, very heavy and difficult to manufacture to the quality needed in a telescope. It would also tend to sag, becoming deformed under its own weight, producing a blurred image. For these reasons the largest refractor used in professional astronomy is the one at Yerkes Observatory. It has an objective lens which is 1 metre in diameter. All telescopes larger than this are reflectors.

It is based at Williams Bay, Wisconsin and was operated by the University of Chicago until its closure in To calculate the magnification of a Galilean telescope, we divide the focal length of the objective by the focal length of the eyepiece. So, if the focal length of the objective is cm and the focal length of the eyepiece is 10 cm, the magnification of the telescope would be To view it, please click on the link below.

My blog explainingscience. It is written in a style that it is easily understandable to the non scientist. Publications and videos For links to my books and videos please visit www. Like Like. Nearsightedness, a more common affliction, proved more difficult to correct. It required biconcave lenses—those curving inward on each surface—that had to bring objects into focus at the specific distance at which one's eyesight failed.

The poorer one's vision, the greater the distance the lenses needed to provide focus. In , someone in Europe—it's not clear who—figured out that if you placed a lens for the farsighted about 12 to 14 inches away from a lens for the nearsighted, and then peered through the latter lens, distant objects would miraculously appear as if close by.

Oh, to have seen that pioneer's expression upon first realizing this! Within months, Galileo had not only learned of the new device but was well on his way to improving its design. In his workshop in Padua, Italy, he discovered that plano-convex and plano-concave lenses worked best—that is, lenses with a plane on one side and curved surfaces on the other.

Then, drawing on his skills as a professor of mathematics at the University of Padua, he determined the mathematical relationship that governed the instrument's ability to magnify. A spyglass with a plano-convex lens that focuses at 12 inches and a plano-concave lens that focuses at four inches, he found, magnifies images three times 12 divided by four.

Galileo played with this formula until, by the late fall of , he'd made a spyglass that could magnify what is seen by 20 times. No other spyglass maker could match that. That fall, Galileo also did what apparently no one else had ever done with a spyglass before: train the instrument on the heavens. In short order he began making astronomical findings that would shake our understanding of our place in the universe to its foundations.

Among them was the discovery of four moons orbiting Jupiter. To Galileo, the moons proved that not everything in space circled the Earth, and therefore our planet was not the absolute center of the universe, as the Church maintained the Bible had it.

For more on the controversy Galileo spawned, see His Big Mistake. Building a better refractor. The spyglass-turned-telescope had limitations, some of which Galileo was able to design around. To reduce distortions such as elongations and blurriness caused by the curvature of the "objective" lens—the convex lens at the far end of the telescope—Galileo ground a lens larger than he needed, for example.

He then placed cardboard around the edges of the lens so that light entered that portion of the lens where curvature-related distortions were least apparent.

Other problems Galileo would have to leave to others. One concerned magnification. In striving to make images he saw through his telescope ever larger, Galileo found that his field of view became ever smaller. He reached a point of diminishing returns beyond which enlarging the image made what was seen through the telescope too small to be of practical use. That point, he found, was achieved when he succeeded in magnifying the image 20 or 30 times.

Galileo's contemporary Johannes Kepler, a German mathematician, discovered a way to get beyond the magnification ceiling. Instead of a concave lens near the eye, Kepler used a convex lens.

The result was that the image magnified by the convex objective lens was further magnified by the now-convex eyepiece lens. The only problem was that the resulting image was upside down.