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What does Kepler's third law tell us?

More distant planets orbit the sun at slower average speeds, obeying a precise mathematical relationship.

Where was the sun located in Ptolemy's model?

Between the orbits of Venus and Mars.

During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars where?

Baghdad. Scholars working in the Muslim Empire translated and saved many ancient Greek works.

Which method of weather prediction did the people of Africa use?

African people learned that the orientation of the crescent of the moon is closely tied to rainfall patterns.

The Polynesian navigators of the South Pacific found their way primarily by observing the position of Polaris in the night sky.

False. They used the waves.

The names of the seven days of the week are based on what?

After the seven naked-eye objects to move along the constellations.

How did the Ptolemaic model explain the apparent retrograde motion of the planets?

Each planet was assumed to move around a small circle that turns upon a larger circle. The resulting path includes a loop in which the planet goes backward as seen from the earth.

What was the ancient goal of astrology?

Forecasting human events

Why was Ptolemy important in the history of astronomy?

He created and published a model that could correctly predict future planetary positions. His model was used for 1500 years.

Who developed a system for predicting planetary positions that remained in used for some 1500 years?


Scientific theories can never be proved true beyond all doubt.


How did Eratosthenes estimate the size of earth in 240 BC?

He did it by comparing the altitude of the Sun on the summer solstice in the Egyptian cities of Syene and Alexandria.

What does Kepler's second law tell us?

As a planet moves around its orbit, it sweeps out equal areas in equal time.

When and where did the Library of Alexandria exist?

It existed in 300 BC for some 700 years. In the city of Alexandria.

Was the Ptolemaic model of the solar system useless for predicting planetary positions?

No, he created a model that could correctly forecast future planetary positions to within a few degrees of arc.

Which scientists discovered the principle that we now call Newton's first law of motion?

Isaac Newton

What is a hypothesis?

A tentative model proposed to explain some set of observed facts, but which has not yet been rigorously tested and confirmed.

Who discovered that the orbits of the planets are ellipses?


When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary motions than the Ptolemaic model. Why not?

The Ptolemaic model accounted for retrograde motion.

At the Sun Dagger in New Mexico, a dagger-shaped beam of sunlight pierces a spiral when?

At noon on the summer solstice


Changed the way we perceive ourselves in the universe


Compiled naked-eye observations accurate to within less than one arc minute


Built the telescope


Law of gravity

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