History of Astronomy Part 2

How did Kepler deviate from the beliefs of Aristotle and Copernicus in his first law?

Kepler was one of the 1st scientists to suggest that the planets revolve around the sun, rather than the earth being the center.

What was the date the last time earth was at perihelion?

On January 4, 2014 the earth was at the perihelion and at that time, the center of the Earth is 147,104,780 kilometers (91,406,672 miles) from the Sun.

What is perihelion? Aphelion?

Perihelion is the point in the orbit of a planet,asteroid or comet at which it is closest to the sun. Aphelion is the point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun.

How did Copernical theory explain retrograde motion?

Copernicus said that the planets closer to the sun moved faster than the ones that were farther away causing what looked like backward motion.

Whose data did Johannes Kepler analyze to arrive at his three laws of planetary motion?

Johannes Kepler analyzed the data of his mentor Tycho Brahe with three statements that described the motion of planets in a sun-centered solar sy

What were three of Tycho Brahe's reason for believing his model had to be right?

he observed a supernova (exploding star) which disappeared after 18 months--conclusion the heavens are not unchanging he observed a comet--which proved that not everything is non-changing and not everything is a circular motion. he measured the movement of planets and stars: couldn't find the parallax, conclusion: the earth is at the center of the universe unmoving.

What is the Copernican theory of the universe?

The Copernican theory says that the Sun is at the center of the Universe, motionless, with Earth and the other planets rotating around it in uniform circular paths modified by epicycles and at uniform speeds.

What key factor kept the Copernican theory from being widely accepted at first?

The key factor was that Copernicus proposed a heliocentric system (sun at the center) and the Roman Catholic Church had decided that the earth was the center of the universe (geocentric system) and that any contrary opinions about that was false.

State Kepler's three laws of planetary motion?

The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The Law of Ellipses) An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of Equal Areas) The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of Harmonies)

Tycho Brahe constructed an observatory in Denmark with the most accurate pre-telescopic observing instruments ever designed. What was the precision of his measurements?

The precision of his measurements was 1 minute of arc, which means a unit of angular measurement equal to 1/60 of one degree.

What was Tycho Brahe's model of the solar sys

Tyco Brahe's model of the solar system placed the Earth at the center and the sun and moon and stars revolve around the earth. The other five planets revolved around the sun. It was a geocentric system. But he said the heavens were not unchanging.

What did Tycho Brahe see in the sky that convinced him that the heavenly firmament was not as unchanging/perfect as he believed?

supernova comet