One night in a cornfield — Part Four

Posted by David Eicher
on Tuesday, July 19, 2011

The first national observatory, in Copenhagen, Denmark, was established in 1637. In the Netherlands, Christiaan Huygens described Saturn’s rings, discovered its moon Titan, and found light and dark markings on Mars. Observatories sprang up in Paris and at Greenwich, England. For the first time, astronomers began observing the sky of the Southern Hemisphere, noting a decidedly different group of stars, constellations, and features from that which they saw from the north.

Photo credit: Adam Block and Tim Puckett
Technologically, all the early telescopes were refractors. That is, they were simple telescopes using a glass lens as a main element at the front of a long tube, and an eyepiece at the rear of the tube to bring the rays of light to focus. Galileo’s first telescopes had objective lenses limited to between ½ and 1 inch in diameter made of glass that took on a greenish tinge from the iron content it held, and a magnifying power of 15x to 20x. However, in 1668, a young English physicist and mathematician, Isaac Newton, invented the reflecting telescope.

Newton was a genius, a jack-of-all-trades who had been born in the British countryside so prematurely his mother had said, “He could have fit inside a quart mug.” Raised by a grandmother, Newton attended Trinity College at Cambridge and, soon after his graduation, began developing the concepts that would lead to his invention of calculus.

He commenced a professorship at Cambridge and taught optics as well as math, which led to his development of the reflector. This type of telescope utilized a polished mirror at the rear end of the tube to reflect light entering back up to a secondary mirror, which diverted it into an eyepiece mounted on the side of the tube.

In 1671, at age 28, he demonstrated his reflecting telescope for the Royal Society. The telescope now commenced its journey through history on a two-track system, one for the original refractor design and the other for the new reflector.

Not to leave unfinished business in the trail of history, Newton also published his monumental Philosophiae Naturalis Principia Mathematica (“Mathematical Principles of Natural Philosophy”), known as Principia for short. It was one of the landmark works in the history of science. In this three-volume tome, Newton revealed his laws of motion, laid the groundwork for classical mechanics, and proposed a law of universal gravitation.

Aside from establishing Newton as the “father of modern science,” Principia ended the dispute over the Earth-centered universe by showing clearly that the Sun is in the center of the solar system. Galileo had died 45 years earlier, after suffering at the hands of the Catholic Church; in the end, Newton’s, Galileo’s, and Copernicus’s ideas prevailed.

TO BE CONTINUED …

Links to Part One, Part Two, and Part Three

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