Ch 27.2 Models of the Solar System

The early oceans became salty when

• dissolved solids were carried from land into the oceans.
• salt dropped from the atmosphere into the oceans
• sea creatures left salty deposits in their remains.

About 99% of all matter contained in the solar nebula now exists in

• planets.
• asteroids.
• space
• the sun

Which of the following do scientists NOT consider a major planet?

• Saturn
• Neptune
• Earth
• Pluto

Small bodies that orbit planets are called

• planetesimals
• protoplanets
• moons
• comets

When early Earth’s atmosphere formed, which of the following gases were lost because Earth’s gravity was too weak?

• oxygen and helium
• helium and nitrogen
• helium and hydrogen
• hydrogen and ozone

Who believed that planets moved in epicycles as they revolved in larger circles around Earth?

• Aristotle
• Newton
• Ptolemy
• Copernicus

The relationship between the average distance of a planet from the sun and the planet’s orbital period is described by the

• law of equal areas
• law of motion
• law of ellipses
• law of periods

Which of the following laws describes the speed at which objects travel at different points in their orbits?

• law of equal areas
• law of eccentricity
• law of ellipses
• law of periods 

The law that describes how a planet orbits the sun is called the scribed by the

• law of orbital periods
• law of ellipses
• law of equal areas

The degree of elongation of an elliptical orbit

• gravity
• orbital period
• eccentricity