According to scientists, both Earth and moon are...

• About 1.6 Billion Years Old
• About 4.6 Billion Years Old
• About 9.6 Billion Years Old
• About 14 Billion Years Old

After water vapor condensed to form rain and then gradually accumulated, which of the following was formed?

• Earth's First Atmosphere
• Earth's Second Atmosphere
• Earth's Oceans
• Earth's Continents

Which of the following is not an important part of Earth's second atmosphere?

• Helium
• Oxygen
• Water Vapor
• Carbon Dioxide

The earliest form of life known on Earth was...

• Leafy Plants
• Bacteria
• Fossils
• Single-Celled Organisms

Scientists believe that __________ and the moon are about the same age.

• Earth
• Comet

According to scientists, Earth began as a ball of dust, rock, and __________.

• Ice
• Gases

___________ pulled this mass together

• Gravity
• Big Bang Theory

A(n) __________________ is a ball of dust, gas, and ice that orbits the sun.

• Comet
• Moon

According to scientists, over billions of years, Earth's ________ have formed, broken apart, and crashed together again.

• Landmasses
• Oceans

Scientists believe that Earth's core and crust formed after the materials pulled by Earth's gravity became very hot and ___________.

• Melted
• Broken