Astronomy. My first Year Notes
written by Kirstie Calderon Lewis
My own notes of Astronomy First Year lesson 1 - 9. All notes from the lessons and my own work on Astronomy. Important information for quizzes and essays can be find within the notes.
Last Updated
05/31/21
Chapters
9
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916
Lesson Nine
Chapter 9
Aristarchus of Samos
• An ancient Greek mathematician and astronomer
• 310-230 B.C.E.
• Born on the Island of Samos
• Invented a widely used type of sundial
• Wrote a book in which he used mathematics to estimate the relative sizes of the Sun and the Moon.
• His observations were wrong, estimating that the distances between the sun and the moon at half moon was 87°, it was in fact 89°50’.
• His estimates of the distances were wrong too: he concluded that the Sun was 18 to 20 times as big as the Moon and 18 to 20 times as far away, whereas the correct ratio, both of size and distance, is around 400:1.
• He did state correctly that Earth is bigger than the Moon, but smaller than the Sun.
• Most famous for having proposed that Earth rotates on its axis, and it rotates around the sun as the other planets do.
• Since the Sun is bigger than the Earth, the Sun should act on Earth more strongly than Earth on the Sun, so the Sun ought to make the Earth revolve around it rather than the other way around.
• His model was condemned as impious by the Stoic philosopher Cleanthes, so he never published it. We know about it through the writings of Archimedes and the ancient Greek biographer Plutarch.
• It was almost unanimously rejected in his time, and for some 18 centuries thereafter, in favour of Ptolemy’s geocentric model, until sometime after it was proposed by Copernicus.
Copernicus
• Nicolaus Copernicus
• 1473-1543 C.E.
• Born in Torun, Poland
• Studied liberal arts, including astronomy and astrology, at the University of Cracow from 1491 to 1494. But left without degree.
• Moved to Italy and studied canon law at the University of Bologna from 1496 to 1500.
• Copernicus studied medicine and astrology at the University of Padua from 1501 to 1503.
• Returned to Poland.
• Employed as a church canon, collecting rent from church-owned land, securing military defences, overseeing chapter finances, managing the bakery, brewery, and mills, and caring for the medical needs of the other canons.
• Worked on astronomy in his spare time.
• Work on observations, eclipses, alignments and conjunctions of the planets and stars.
• He knew that Aristarchus had long ago proposed that Earth rotates about an axis and that the planets, including Earth, revolve around the Sun, and his observations led him to suspect that this model was correct.
• He observed that the calendar then in use had fallen seriously out of alignment with the actual position of the Sun.
• Earth’s axis was not fixed but itself rotates, a phenomenon now known as the precession of the equinoxes.
• He wrote a six-part book whose title in English is "Six Books Concerning the Revolutions of the Heavenly Orbs".
• Never gave Aristarchus any credit for having proposed that same model some 18 centuries earlier.
• His theory wasn’t generally accepted at the time, largely because it didn’t accurately predict the motion of the planets.
• Von Rheticus convinced Copernicus to publish his book 1543.
• Death 1543.
• An ancient Greek mathematician and astronomer
• 310-230 B.C.E.
• Born on the Island of Samos
• Invented a widely used type of sundial
• Wrote a book in which he used mathematics to estimate the relative sizes of the Sun and the Moon.
• His observations were wrong, estimating that the distances between the sun and the moon at half moon was 87°, it was in fact 89°50’.
• His estimates of the distances were wrong too: he concluded that the Sun was 18 to 20 times as big as the Moon and 18 to 20 times as far away, whereas the correct ratio, both of size and distance, is around 400:1.
• He did state correctly that Earth is bigger than the Moon, but smaller than the Sun.
• Most famous for having proposed that Earth rotates on its axis, and it rotates around the sun as the other planets do.
• Since the Sun is bigger than the Earth, the Sun should act on Earth more strongly than Earth on the Sun, so the Sun ought to make the Earth revolve around it rather than the other way around.
• His model was condemned as impious by the Stoic philosopher Cleanthes, so he never published it. We know about it through the writings of Archimedes and the ancient Greek biographer Plutarch.
• It was almost unanimously rejected in his time, and for some 18 centuries thereafter, in favour of Ptolemy’s geocentric model, until sometime after it was proposed by Copernicus.
Copernicus
• Nicolaus Copernicus
• 1473-1543 C.E.
• Born in Torun, Poland
• Studied liberal arts, including astronomy and astrology, at the University of Cracow from 1491 to 1494. But left without degree.
• Moved to Italy and studied canon law at the University of Bologna from 1496 to 1500.
• Copernicus studied medicine and astrology at the University of Padua from 1501 to 1503.
• Returned to Poland.
• Employed as a church canon, collecting rent from church-owned land, securing military defences, overseeing chapter finances, managing the bakery, brewery, and mills, and caring for the medical needs of the other canons.
• Worked on astronomy in his spare time.
• Work on observations, eclipses, alignments and conjunctions of the planets and stars.
• He knew that Aristarchus had long ago proposed that Earth rotates about an axis and that the planets, including Earth, revolve around the Sun, and his observations led him to suspect that this model was correct.
• He observed that the calendar then in use had fallen seriously out of alignment with the actual position of the Sun.
• Earth’s axis was not fixed but itself rotates, a phenomenon now known as the precession of the equinoxes.
• He wrote a six-part book whose title in English is "Six Books Concerning the Revolutions of the Heavenly Orbs".
• Never gave Aristarchus any credit for having proposed that same model some 18 centuries earlier.
• His theory wasn’t generally accepted at the time, largely because it didn’t accurately predict the motion of the planets.
• Von Rheticus convinced Copernicus to publish his book 1543.
• Death 1543.
