The history of astronomy is sprinkled with important discoveries, technologies, and insights. All three of them came together in the year 1609 to revolutionize humanity's view of the universe -- both what we could actually see, and how we understood what it all meant.
Astronomers are celebrating that revolution this year. The commemoration is called the International Year of Astronomy.
In 1609, Italian astronomer Galileo Galilei heard of a remarkable new technology -- the telescope. It had been invented the year before in Holland, but was more of a novelty than a scientific tool. Galileo built one of his own from descriptions of the Dutch instruments.
Next, Galileo turned his new tool toward the sky, and he made discoveries galore. He saw remarkable details on the Moon. He saw thousands of individual stars in the hazy band of the Milky Way. He discovered moons orbiting Jupiter, and phases for Venus. He even mapped dark "spots" on the Sun.
Galileo's discoveries rearranged the universe. The phases of Venus confirmed that Earth and the other planets orbit the Sun. The stars of the Milky Way showed that the universe is more extensive than anyone had known. And the features on the Moon and Sun showed that neither body is smooth and unchanging, but that the universe is dynamic and feature-packed.
Astronomers are still exploring Galileo's universe four centuries later -- and celebrating his revolution all year long.
Script by Damond Benningfield, Copyright 2008
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