Perihelion – when a planet is closest to the sun in its orbit.

Aphelion – when a planet is farthest from the sun in its orbit.

Ellipse – the oval shaped path that a planet takes around the sun.

Geocentric Model of SS – Earth is at the center of the SS

Heliocentric Model of SS – Sun is at the center of the SS

Roman Astronomer, mathematician, and geographer

Thought Earth was at the center of the solar system (Geocentric model of the SS)

Thought that all the planets traveled in smaller circles, called epicycles.

Scientist during time of Renaissance

Thought the sun was the center of our SS(Heliocentric model of SS)

Also proposed the idea that Earth was tilted

He and his followers had to study in secret

He was the first to use telescopes to observe space

He discovered 4 moons around Jupiter

He discovered the phases of Venus

He observed the surface of the moon and the sun.

Built an observatory and recorded the positions of the stars and planets for 20 years.

At age 20, he was in a duel and lost part of his nose. He wore a metal insert over the missing part.

Brahe’s assistant and mathematician

Published the Laws of Planetary Motion in 1609 – 1618.

Kepler's First Law of Planetary Motion states that the orbits of the planets are ellipses with the sun at one focus of the ellipse.

Equal Area Law - states that a line from a planet to the sun will sweep out equal areas in equal times. The planet moves more slowly when it is farther from the sun and faster when it is near it.

Harmonic Law – states that the farther a planet is from the sun, the slower its speed and the longer its period of revolution.

The Universal Law of Gravitation states that the force of gravity between two objects is dependent on the mass of the objects and their distances from each other.

Perihelion – when a planet is ___________ to the sun in its orbit.

Aphelion – when a planet is ___________ from the sun in its orbit.

Ellipse – the oval shaped path that a ________ takes around the _______.

Geocentric Model of SS – ________ is at the center of the SS

Heliocentric Model of SS – _________ is at the center of the SS

________ Astronomer, mathematician, and geographer

Thought ______ was at the center of the solar system (_________ model of the SS)

Thought that all the planets traveled in smaller circles, called __________.

Scientist during time of ________________

Thought the ______ was the center of our SS(____________ model of SS)

Also proposed the idea that _____ was ______

He and his followers had to _______ in secret

He was the first to use ___________ to observe ______

He discovered 4 moons around ________

He discovered the __________ of Venus

He observed the ________ of the _______ and the _______.

Built an ___________ and recorded the positions of the _______ and _________ for 20 years.

At age 20, he was in a _____and lost part of his ______. He wore a metal insert over the missing part.

Brahe’s _________ and mathematician

Published the _____ of Planetary ______ in 1609 – 1618.

Kepler's First Law of Planetary Motion states that the ______ of the planets are ______ with the _____ at one focus of the ellipse.

______ Area Law - states that a line from a planet to the sun will sweep out _____ areas in equal times. The planet moves more ______ when it is farther from the sun and ______ when it is near it.

_________ Law – states that the _______ a planet is from the sun, the slower its ______ and the longer its period of __________.

The __________ Law of Gravitation states that the force of _______ between two objects is dependent on the _____ of the objects and their _______ from each other.