Staring into Space For hundreds of years humans have looked up at the night sky and asked questions about what they saw What is the Sun How many other planets are there How far away are the stars Ancient astronomers did not have telescopes or spacecraft to find the answers Their knowledge of space was based on what they could see with the naked eye The prehistoric monument Stonehenge in the U K may be linked to astronomy From a certain position the Heel Stone pictured here in the center lines up with the sunrise in midsummer and sunset in midwinter 6
EARLY EXPLORATION Ancient Astronomy In ancient times people set their calendars by the movements of the Sun and Moon They discovered that objects in space had an effect on the weather and the tides Tides are the way the sea rises and falls throughout the day They saw their heroes and gods in the patterns of the stars called constellations The science of astronomy or the study of space may have begun in China around 6,000 years ago The name comes from two Greek words meaning star and law astronomers scientists who study objects in space 7
Astronomy in Ancient Greece The ancient Greeks began applying math to the movement of objects in space They discovered that Earth moved around the Sun and that the Moon traveled around Earth Greek astronomers were the first to realize that Earth must be round They also worked out what caused eclipses The Greek astronomer Anaxagoras figured out that a solar eclipse was caused when the Moon passed between the Sun and Earth Everything has a natural explanation The Moon is not a god but a great rock and the Sun a hot rock Ancient Greek astronomer Anaxagoras 8
EARLY EXPLORATION A Closer Look In 1609 the Italian astronomer Galileo Galilei was the first person to look at the night sky through a telescope He made many discoveries including the rings around Saturn and Jupiter’s moons Telescopes showed that there was a lot more to space than anyone had ever imagined But it was many years later before people had the technology to travel into space Galileo drew sketches of the Moon showing the mountains and craters he saw on its surface eclipses when an object in space blocks the light from another object 9
