Astronomy Unit 10 A theory of the origin and nature of the universe is termed a cosmology Science is a theory of the origin of the universe incorrect Thales of Miletus was an early astronomer of the Greek world correct Thales of Miletus is best known for predicting an eclipse The first astronomer recorded to believe the Earth rotated about the Sun was Philolaus Philolaus is known for introducing the idea that the Earth is in motion Anaximander is known for his eclipse predictions incorrect Eratosthenes was the first astronomer to correctly measure the Earth s size correct The early Greek astronomer who is first recorded as believing that the heavenly bodies are spherical in shape was Pythagoras The curved terminator of the Moon was used by the Greek astronomers of the Pythagorean School to infer that the moon and Earth were round spherical The shape of the Moon s terminator gives definite evidence that the moon was spherical The curved shadow of the Earth on the Moon during a lunar eclipse was evidence used by olden time astronomers to infer the Earth had a spherical shape Anaxagoras deduced the true cause of eclipses correct The round shadows during lunar eclipses were used by Greek astronomers of the Anaxagonian School to infer that the Earth was round spherical The philosopher first known to press the idea that astronomy contributed to civilization was Plato Aristotle believed the Sun was further away than the Moon correct Aristotle deduced the relative sizes of the Sun and Moon incorrect An early Greek who gave a clear and correct explanation of the phases of the Moon was Aristotle An early Greek astronomer who believed in spherical Earth and who was the first to explain the phases of the Moon was Aristotle Aristotle is known for explaining the phases of the Moon Aristarchus of Samos is famous for his calculations of the relative distances of the Sun and Moon Aristarchus deduced the approximate relative sizes and distances of the Sun and the Moon correct Herodotus was the first astronomer to obtain a reasonably correct value for the Earth s diameter He made his observations with a well at Alexandria when the Sun was at the zenith at Syene Wrong Eratosthenes did this the well was at Syene measured angle at Alexandria First known astronomer to correctly measure the Earth s size was Eratosthenes Hipparchus is known for his star catalogue The concepts of eccentrics and epicycles were introduced by Hipparchus Eratosthenes discovered the precession of the equinoxes incorrect Precession was discovered by Hipparchus The Almagest was written by Ptolemy One of the basic differences between early Greek science and modern science is importance of observation and experiment in modern science Early Greek science was noted for its observational and experimental work wrong both of these were its weakest points 7 61 x 2 0 15 only 2 sigfig trailing 0s are signif 7 61 x 2 00 15 2 3 sigfigs Al Battani was an early Indian Italian astronomer incorrect Among other things Al Battani is known for his measurements of the mass of the Sun incorrect known for his determination of the shape of the Earth s orbit The Arab astronomer best known in medieval Europe was Muhammad Al Battani The resolution of the human eye is about 2 All the concepts of astronomy were developed by Western European civilization Incorrect Islamic East Indian Chinese and Japanese societies developed some concepts independently Polynesian and Native American societies developed some concepts independently The parallax we see in the position of a nearby star is caused by that star s motion incorrect The shift in the apparent position of a star due to the Earth s motion about the Sun is measured by the star s parallax A 2 meter tall man is observed to have an angular height of 57 degree 2060 How far away is he 200m Venus is about 1 2 x 10 4 km in diameter and sometimes is as close as 4 0 x 10 7 km What is Venus approximate angular size when it is closest 63 A space satellite 1 meter in diameter is circling the Earth It is observed to have an angular size of 2 06 seconds of arc The distance to the satellite is 10 7 A space satellite 1 meter in diameter is circling the Earth It is observed to have an angular size of 0 206 seconds of arc The distance to the satellite is 10 8 When Mars is closest to the Earth its angular diameter is about 17 and its distance is about 7 7 x 10 7 km The approximate diameter of Mars is 6 4 x 10 3 If a is the angular size of an object in seconds of arc d its real size and r the distance to the object these quantities are related by a 206265 d r The model of the solar system which involved deferents and epicycles was devised by Ptolemy Ptolemy s solar system model had all the planets and the Sun move about the Earth The system of answering questions about nature by observations or experimentation is called science If you are at latitude 34 degrees N then on the winter solstice the altitude of the Sun above the southern horizon at noon is approximately 32 5 degrees If you are at latitude 34 degrees N then on the summer solstice the altitude of the Sun above the southern horizon at noon is 79 5 degrees If you are 90 degrees N then on the summer solstice the altitude of the Sun above the southern horizon at noon is approximately 23 5 degrees