Formation of the Solar System

What two factors affect the gravitational attraction between two objects?

• surface area and mass
• distance and circumference
• volume and mass
• distance and mass

A cloud of gas and dust from which bodies in space are formed

• photosphere
• nebula
• solar flare
• Sunspot

What force "holds" the planets in orbit?

• inertia
• gravity
• air pressure
• magnetism

what happens during nuclear fusion in the sun?

• oxygen nuclei combine to form helium
• Helium nuclei combine to form oxygen
• helium nuclei combine to form hydrogen
• hydrogen nuclei combine to form helium

how might Earth be affected by the activity of sunspots on the sun's surface?

• sunspot activity might affect Earth's temperatures
• low sunspot activity might contribute to global warming
• sunspot activity could send electrically charged particles into Earth's atmosphere
• sunspot activity has bee linked to hurricanes

In what layer of the sun is energy produced?

• photosphere
• convective zone
• chromosphere
• core

the planets of the solar system formed as 

• the center of the gas cloud cooled
• planetesimals flattened into a rotating disk
• planetesimals collided into one another
• the sun absorbed extra gas and dust from the solar system

what may have caused oceans to form during Earth's second atmosphere?

• the Earth had cooled enough for heavy rain to follow
• Nitrogen gases condensed into water
• the moon released icy dust particles that crashed into Earth
• millions of years of meteor showers fell upon Earth

Earth's early continents formed as rocks melted and 

• absorbed much of the water covering the planet
• Lighter materials rose above the ocean's surface
• the heaviest materials rose to form the planet's crust
• sank below the ocean's surface

Earth's period of revolution is about

• one day
• one week
• One year
• One hour