Front

What does "geocentric" mean?

Back

The geocentric theory says that Earth is at the center of the universe and everything — the sun, stars, and planets — revolves around it.

Front

Which ancient civilization believed in the geocentric theory?

Back

The ancient Greeks believed in the geocentric model of the universe.

Front

What does "heliocentric" mean?

Back

The heliocentric theory says that the sun is at the center of the universe, and Earth and the other planets revolve around it.

Front

Who first proposed the heliocentric theory?

Back

Nicolaus Copernicus proposed the heliocentric theory in the 1500s.

Front

What was one major difference between the Greek model and Copernicus' model?

Back

The Greeks believed Earth was the center (geocentric), while Copernicus believed the sun was the center (heliocentric).

Front

Who discovered that planets move in elliptical orbits, not perfect circles?

Back

Johannes Kepler discovered that planets move in elliptical (oval-shaped) orbits around the sun.

Front

How did Kepler improve the heliocentric model?

Back

Kepler showed that planets orbit the sun in ellipses, not perfect circles, making the model more accurate.

Front

Compare geocentric and heliocentric theories.

Back

Geocentric: Earth at the center. Heliocentric: Sun at the center.

Front

Contrast the beliefs of Greeks, Copernicus, and Kepler.

Back

- Greeks: Earth-centered (geocentric) - Copernicus: Sun-centered (heliocentric) - Kepler: Sun-centered with elliptical orbits (improved heliocentric model)

Front

What was the main contribution of Copernicus to astronomy?

Back

Copernicus introduced the heliocentric model, which placed the sun at the center of the universe, challenging the long-held geocentric model.