Johann Kepler - a Legislator of the Sky. The laws of the planets movements put by Johann Kepler destroyed the thousand year old dogmas about the circles and spheres and opened the way to scientific understanding of celestial occurrences. ... The best object for observation was Mars - its orbit unlike the Earth's one has a noticeable eccentricity, the rotation period in comparison with Jupiter and Saturn is not too long and observation conditions are better than for Mercury and Venus. ...