Sky Science

  Modern Astronomy Connection: Sky Science

People in ancient Greece watched the night sky and tracked carefully the movements of the Moon and stars as they changed positions in the night. They named five planets (wanderers which do not seem to move in a pattern): Mercury, Venus, Mars, Saturn, and Jupiter. They estimated the distance from the Earth to the Sun and Moon.

Aristotle

Aristotle observed that the stars move together in patterns that do not seem to change (constellations). He knew that northern and southern constellations are different. Aristotle knew the Earth was round because he observed the curved outline of lunar eclipses. He also tracked the shadows cast by objects.

On the other hand, Aristotle made some key mistakes. He imagined the universe as a giant onion with many layers. He thought the Earth was the centre of the universe and the universe revolved around it. Because of Aristotle, people for a thousand years believed that the Earth was the centre of the universe and that the sun, planets, and stars moved around the Earth.

Galileo Galilei

More than a thousand years after Aristotle, Galileo constructed the very first telescope. He held two lenses together to get a clearer view of the sky. Galileo was one of the first astronomers to describe our solar system based on careful recorded observations and calculations. With better instruments, people were able to see that the Sun is the centre of our solar system and the planets move around it.

Today, we can use powerful telescopes that can be sent into the far reaches of space. We have access to far more information than people had centuries ago. Our understanding of space and time is drastically different; however, we remain in awe of the vastness of our universe. There is still much to be discovered.

  Video

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The video below explains how much Galileo was able to learn from observing the sky using the simple instruments he had available at the time.