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- It was only 90 years ago that astronomy started exploring outside the Milky Way Galaxy. It was when Edwin Hubble discovered "spiral nebula" in the constellation of a Andromeda. That was another galaxy. And, that is what started our exploration outside our own galaxy. 400 BC was when astronomy started in the course of human history. That was when Aristotle figured out the eclipse on the moon was actually Earth's shadow. Therefore, Earth was not flat it was a sphere. In some sense that was the first planet discovery.
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----- 400 B.C. ----- Aristotle was a Greek philosopher you lived in the years 384 to 322 B.C. He lost both his parents as a child and was brought up by a friend of the family. He started his college education in Athens at each a 17. He joined Plato's Academy before Plato died in 347 B.C. He became the tutor for Alexander the Great. In 327 B.C. he started his own school lecturing students in his garden while walking around. His lectures were collected in to 150 volumes. His teachings accepted the Pythagorean notion of the roundness of Earth. When he traveled north the southern stars disappeared below the horizon. When the eclipse was viewed on the moon his theory was validated. Earth was a sphere.
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----- 1543 ---- In 1543 Nicholas Copernicus announced to the world that the Earth was not the center. The Sun was the center and Earth was just one part of the solar system.
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- Copernicus was a Polish astronomer living from 1473 to 1543. His father was a copper merchant. In 1491 he studied math. In 1496 he studied medicine in Italy. In 1507 he determined that the position of the planets could be calculated more easily if you assume the Sun was the center of an ellipse rather than the Earth being the center and the orbits being circles. In 1512 he published the mathematical details of these calculations, including the calculating the length of a year to within 28 seconds. These calculations also accurately explained the retrograde motion of Mars, Jupiter, and Saturn. His book was published in 1543, the year that he died.
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------ 1600 ---- 1600 Johannes Kepler did the math for the elliptical orbits of the planets around the Sun. He concluded that each planets orbit swept out equal areas in equal times. The square of the planets orbit is proportional to the cube of the radius from the Sun.
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- Johannes Kepler was a German astronomer living from the years 1571 to 1630. He was the son of a professional soldier. He contracted smallpox at the age of 3 crippling his hands and weakening his eyesight. He was brilliant in mathematics and was teaching science at the University in Austria. He became an astrologer and performed horoscopes for the Emperor. In 1598 he worked in Prague with Tycho Brach. In 1601 he inherited Tycho's astronomical data on planetary motion. September 30, 1604 he witnessed the supernova, that is now named after him.
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- He could not make spheres match Tyco's data on planetary orbits. He discovered that an ellipse fit the data and in 1609 he published the second law that a planets orbit sweeps out an equal area in equal time. Planets closer to the Sun orbit faster. Kepler's third law was that the square of the period of orbit is proportional to the cube of the distance from the Sun. Kepler corresponded with Galileo and used Galileo's telescope to observe Jupiter's four moons. He had 13 children but still had time to predict the transits of Mercury and Venus across the face of the Sun.
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------ 1610 ---- In 1610 Galileo observed the phases of Venus similar to the phases of the moon. This observation convinced Galileo that Copernicus was right. Also in 1610 when he discovered the moons orbiting Jupiter, it was a first time science had discovered satellites orbiting another body.
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- Galileo lived from 1564 to 1642. His father was a mathematician. In 1581, at age 17, he watched a swinging chandelier and devised the math for pendulums. He used his pulse rate for the clock. He conjectured that all objects fall at the same rate regardless of mass contrary to Aristotle's teachings. He invented the science of gunnery by defining the projectile’s trajectory as a parabolic curve.
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- In 1609 he constructed his first telescope and microscope. He used sunspots to determine the Sun's rotation rate to be 27 days. He deduced that the stars were much farther distant than the planets. He calculated the orbits of the four moons of Jupiter, and discovered the phases of Venus. He discovered earthshine on the Moon. He was the best lens maker in Europe and built dozens of telescopes. In 1633 he was convicted of heresy for his ideas. It was not until 1965 that the Catholic Church admitted it was wrong.
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------ 1796 ---- In 1796 Laplace mathematically established the stability of our planetary solar system. He proposed how it evolved from a dust rich nebula in to the rotating accretion disk orbiting the Sun and forming the planets.
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- Pierre Simon Laplace lived from 1749 to 1827. At the age of 18 he wrote a paper that got him a professorship in mathematics in Paris. He studied the eccentricity of the planetary orbits of the solar system. In 1799 he published a five volume work called "Celestial Mechanics". Then Napoleon made Laplace his Minister of Interior. In 1817 he became president of the French Academy. In 1812 he wrote a theory of probability. He proposed that the Sun originated as a giant nebula of gas that was in rotation with the rim of the gas condensing into planets.
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------ 1800 ---- In 1800 Piazzi discovered the asteroid Ceres orbiting between Mars and Jupiter. At the time it was thought to be the 5th planet in the solar system.
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- Giuseppe Piazzi was in an Italian astronomer living from 1746 to 1826. In 1764 he entered the order as a Theatine Monk. In 1780 he was put in charge of a Naples’s Astronomy Observatory. By 1814 he had mapped the position of 7,646 stars. In 1801 he discovered the dwarf planet Ceres. Ceres' diameter is only 485 miles. It was the beginning of the discoveries of 1,600 asteroids in the Asteroid Belt orbiting between Mars and Jupiter.
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RSVP, with comments, suggestions and corrections. An index of all reviews is available. Some reviews are at: -------------------- http://jdetrick.blogspot.com
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------ www.twitter.com or cell: 707-536-3272 ------ Sunday, December 8, 2013
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