Astronomy is by far the oldest science in existence, going as far back as 6,000 years. Nearly every civilization that has lived on earth has wondered about the Sun, the Moon and the stars and each has formed their own opinions about what it all meant and how it worked.
Astronomy the Greek Way
The ancient Greeks, who lived in a world full of intellectual freedom, were one of the first civilizations to make scientific progress in the field of Astronomy. Many Greek philosophers sought to answer age old questions about the sky. Heraclitus put forth the idea that the each night the stars were lit and each morning the sun was lit, much in the same way that oil lamps are. Aristotle believed that the earth was at the center of what we now term the universe. Despite these wild speculations the Greeks made serious progress in the fields of geometry and trigonometry which then enabled them to begin the task of measuring astronomical distances. Around the year 500 BCE Pythagoras stated that the Earth, the Sun, and the Moon and other planets were spherical in shape. Aristotle backed up this idea by observing the shape of the earth’s shadow during a lunar eclipse.
Copernicus and the Birth of Modern Astronomy
In the year 1543 Nicolaus Copernicus published a treatise that talked about the universe as having the sun at the center rather than earth. This theory where the earth orbited the sun solved many of the problems that cropped up with previous theories although it also created an issue or about the stars. People wondered that if the sun was at the center and the earth moved around it, why then did the stars not also move. Copernicus answered this by placing stars at enormous distances away from earth so that their movements simply wouldn’t be noticeable from earth.
Three Laws of Planetary Motion
Johannes Kepler, who lived in the late 16th to early 17th century, formulated what are now known as the three laws of planetary motion. The first law was formulated in 1609 and showed that the orbits of all planets are not circular but elliptical. His second law revealed that a planets orbiting speed is slower when it reaches the far ends of its orbit. In 1619 Kepler proved the relationship between the size and the period of an orbit. After Kepler the next major astronomical discoveries came from Galileo.
With the advent of the telescope major advances in the field of astronomy began to emerge. Galileo produced his own telescopes which could magnify up to 30 times. He made several major discoveries just by observing with the telescope. One of the major discoveries made by Galileo was that the planet Venus goes through several phases much like the moon. He was also the first to indicate that the moon was covered in both mountains and craters.
Modern Astronomy would not be possible without all of the small steps made by men from earlier centuries. Without the earliest telescopes today’s high powered ones would never have been invented.
Source: Rees, Martin. Universe: The Definitive Visual Guide. DK Publishing, New York. 2008.