Others, after finding something that contradict the views and beliefs of the Church, kept their findings for themselves, not letting the world of their discoveries because of the fear of persecution. As a result, there had been few published books or articles regarding developments in the field of astronomy that contradicts the view of the church. Thus, the church really hinders the development of astronomy because it contradicts their beliefs and teachings and was creating doubts in the perfection of the universe. It took a very long time to be able to accept developments and new knowledge in astronomy.
2.) Tides refer to the alternating rise and fall of sea level within a day. What causes the sea level to change? It is actually the gravitational attraction of the sun and moon that cause waters of the ocean to swell and recede at different parts of the earth. The earth and the moon are two great masses that have a significant gravitational pull on each other. This keeps the moon in orbit around the earth, and it is also what causes tides to occur in the ocean.
The fact that there are two tide cycles a day instead of just one can be cogently explained. Although we commonly think of the moon as revolving around the Earth they both revolve around their common center of gravity. The revolution of the earth and the moon about their own center of gravity counterbalanced the gravitational attraction between them. This balance in between the centrifugal force and the gravitational force between the earth and the moon appear exactly at their centers, in the center of the earth and the moon. The earth experiences gravitational and centrifugal forces resulting in the earths water to assume ellipsoidal.
As the earth turns upon its own axis in about 24 hours, a point on the earth moves through areas with these different forces acting on it. In one rotation (one day), a point on earth travels from an area of high tide, where the earths water is being pulled outward, to an area of low tide where the earths water is being pulled inward, trough another area of high tide which is the opposite pull to another area of low tide. Then it will return to its point of origin at high tide. Thus, two high tides and low tides can be observed instead of just one in a day.
3.) Johannes Kepler was born in Wurttemberg in 1571 and died in 1630. He received an excellent and wide-ranging education in Lutheran Schools and at the University of Tubingen. He hoped to follow a carrier in the church, but he wrote paper on an astronomical subject that came to the attention of Tycho Brahe, now at Prague, and Tycho invited the young man to join him as his assistant. After much soul searching, Kepler accepted, and when Tycho died the next year, in 1601, Kepler was appointed imperial mathematician in his place and inherited Tychos large body of accurate astronomical observations.
Keplers greatest contribution was a set of three laws of planetary motion that solved the problem of epicycles and eccentric orbits once and for all. The first of the new laws made a substantial change in the Aristotelian system, for it asserted that planetary motion is not uniformly circular. The planets do not travel in eccentric circles around the sun, but in ellipses, with the sun at one of the two foci of the ellipse. Keplers ellipses were very close to circles, which explained why the previous assumption of circular orbits had adequately explained the phenomena as long as observations remained relatively inaccurate. The new assumption was correct within the limits of observational accuracy of the time and required no further adjustments, no eccentricities, no epicycles, and no tricks of any kind.
Keplers second law of planetary motion asserted that a radius vector joining a planet to the sun sweeps out equal areas in equal time. What this mean is that in a certain time, a planet will travel more quickly along its orbit when it is closer to the sun than when it is farther away from it. This brilliant insight, a major inspiration to Newton, applies to all bodies moving in fields of force, not just planets. It explained most of the discrepancies between astronomical theory and observation.
The third law asserted a mathematical relation between the periods of revolution and of the planets and their distance from the sun. Discovering this law was a remarkable achievement considering the primitive instruments Kepler had at his proposal.
Kepler spent many years not only advancing his ideas about these laws and preparing Tychos tables of observation for publication, but also mulling over what he recognized as the great remaining unsolved problem of planetary motion: the motivation whereby the planets revolved around the sun. What holds the planets in their orbits and what drives them ever forward.