PIONEERS IN ASTRONOMY AND SPACE EXPLORATION Many of the great thinkers of the time including Aristotle based their work on Eudoxus s model of the universe amending various parts as new information came to light This set the pattern for the advance ment of astronomy as a science with new theories building on those that came before Hipparchus and Ptolemy used the meth ods devised by Aristarchus of Samos in an attempt to figure out the size of the Moon and its distance from Earth Also influenced by Aristarchus was the father of modern astronomy Nicolaus Copernicus whose own theories were later championed by Galileo Tycho Brahe shared his data with Johannes Kepler who in turn greatly influenced Sir Isaac Newton Intrigued by the observations of astron omers and in some cases by science fiction stories as well physicists and engineers of the 20th century developed the technology that would allow for exploration in space The work of Robert H Goddard Wernher Von Braun and other rocket scientists led to spacecraft that would launch humans into orbit The earliest pioneers who rode those rockets into space came from the former Io
INTRODUCTION Soviet Union now Russia and the United States In a race to space each country tried to outdo the other with its achievements in exploring the so called final frontier Soviet cosmonaut Yury Gagarin won the title of first human in space over American astronauts Alan B Shepherd who made a suborbital flight about three weeks after Gagarin's fight and John Glenn the first American to orbit Earth Americans how ever were first to land on the Moon where Neil Armstrong and Buzz Aldrin explored the surface and planted an American flag Women also made their mark as space explorers Valentina Tereshkova of the Soviet Union was the first woman to travel in space while Sally Ride was the first American woman to do so Although tragedy cut her journey short of its goal teacher Christa McAullife was chosen as the first private citizen to travel into space aboard the U S space shuttle Challenger These days space pioneering is done mostly by unmanned satellites which travel to distant locations and beam images back to Earth Yet humans may once again venture deep into space spurred on by the accom plishments of pioneers from days gone by II
CHAPTER 1 EUDOxUS OF CNIDUS Greek mathematician and astrono mer Eudoxus of Cnidus contributed to the identification of constellations and thus to the development of astronomy in ancient Greece He also established the first sophisticated model of planetary motion Eudoxus was born around 395 390 BCE in Cnidus Asia Minor now in Turkey He studied mathematics and medicine and later went to Athens where he took part in philosophical discussions at the famous Academy directed by the philosopher Plato He eventually returned to Cnidus where he became alegislator and continued his research until his death at age 53 In his astronomical works Eudoxus mapped out the constellations and described the phases of fixed stars the dates when they are visible He also discussed the sizes of the Sun Moon and Earth Perhaps Eudoxus s greatest fame stems from his being the first to create a geometric model of the motions of the Sun the Moon and I2
EUDOXUS OF CNIDUS the five planets known in ancient times His model consisted of a complex system of 27 interconnected spheres with Earth at the center One sphere held the fixed stars while each planet occupied four spheres and and had the Sun Moon three each Callippus and later Aristotle modified the model Aristotle's endorsement of its basic principles guaranteed an enduring interest through the Renaissance Most astronomers seem to have aban doned the astronomical views of Eudoxus by the middle of the 2nd century BCE Nevertheless his principle that every celestial motion is uniform and circular around the center endured until the time of the 17th century astronomer Johannes Kepler 13
