Brown Astronomy Unit 2 Webassign Questions

As Saturn lies at about 10 AU from the Sun, out there the Sun's gravity would be

100 times weaker

Compared to orbital velocity, escape velocity is about

41% greater

On what did Copernicus and Ptolemy agree?

All orbits are circular

Upon which point did Kepler and Copernicus disagree?

All planetary orbits must be circular

The Copernican heliocentric model was actually first proposed by

Aristarchus

Which of these concepts was NOT part of Ptolemy's model?

Planets moved in ellipses

Which concept below was NOT part of Kepler's Laws?

Retrograde motion requires epicycles when the planet lies at opposition, closest to us.

Retrograde motion

Describes the portion of a planet's path in the sky when it stops moving eastward and for a while turns westward

The Ptolemaic model of the universe

Explained and predicted the motions of the planets with deferents and epicycles

What was one of Newton's contributions to astronomy?

He developed a theory of gravity that could explain orbital motion

What contribution to astronomy was made by Tycho Brahe?

He made extensive and detailed observations of the positions of the planets

What was one of the contributions made by Copernicus to astronomy?

He said that the Earth is not the center of the universe

Which of the following is one of the many contributions made by Galileo to astronomy?

He used a telescope to observe sunspots and the rotation of the Sun

The force of gravity between two objects

Increases with the mass of the objects and decreases with the distance between them

Scientists today do not believe the Ptolemaic model because

It has been proven to be incorrect

The Ptolemaic picture of the universe probably survived for so long because

It is consistent with the doctrines of the Church

What was the greatest contribution of the Greeks to modern thought?

Their concept of the universe as something to be studied, questioned, and explained

Long ago, people probably observed the heavens because

They relied on their knowledge of the heavens to know when to plant crops and how to navigate ships