# pre1900

### johannas kelper

## Discovery Of The Solar System

The main idea of the solar system was proposed by the Polish astronomer Nicolaus Copernicus (1473-1543) who said that "the Sun is the center of the Universe" and made the planets move around it in perfect circles (in his book entitled, "On the Revolution of the celeste sphere written in Latin and published in 1543).The German astronomer Johannes Kepler (1571-1630) supported the Copernican concept that the Sun is at the center, but gave to the planets elliptical orbits, with the Sun in one of the center of each ellipse to describe their complicated motions more correctly.

## Erlay Modern World

1605 - The German mathnematician and astronomer Johannes Kepler establishes his three Laws of Planetary Motion, mathematical laws that describe the motion of planets in the Solar System, including the ground-breaking idea that the planets follow elliptical, not circular, paths around the Sun. Newton later used them to deduce his own Laws of Motion and his Law of Universal Gravitation.

## Dates

1602 is when Johannas Kepler introduced first two Law of Planetary Motions .In 1611 he introduced the third Law of Planetary Motion.Also in 1631 Kepler successfully predicts the motion of Mercury.

## 1930

Christoph Scheiner had built a telescope based on design that Johannas Kepler had made in 1611. Johannas designs helped Galileos by replacing the lenses . This helps to reduce rounded aberrations. Astronomers find spherical aberration quite annoying as it means that they do not get perfect images when they look through their telescopes

## Kepler's first law Ellipses are described mainly by the length of their two axes. A circle has the same diameter whether you measure it across or up and down. But an ellipse has diameters of different lengths. The longest one is called the major axis, and the shortest one is the minor axis. The ratio of these two lengths determines oddness the of the ellipse; it's a measure of how elliptical it is. Circles have e=0, and very stretched-out ellipses have an eccentricity nearly equal to 1. | ## Kepler's second law Kepler realized that the line connecting the planet and the Sun sweeps out equal area in equal time. Look at the diagram to the left. What Kepler found is that it takes the same amount of time for the blue planet to go from A to B as it does to go from C to D. | ## Kepler's third law Kepler's 3rd law is a mathematical formula. It means that if you know the period of a planet's orbit then you can determine that planet's distance from the Sun It also tells us that planets that are far away from the Sun have longer periods than those close to the Sun. They move more slowly around the Sun. |