Earth Theory Questions And Answers
1. Suppose you are an alien explorer from outer space looking for life on other planets. Your spaceship flies into a group of stars that looks like a gigantic whirlpool. The whirlpool is the
Answer: Milky Way Galaxy.
2. Suppose an alien explorer heads for a star with eight planets in one arm of the Milky Way galaxy. The third planet from the star is a beautiful blue, white and green ball. This planet looks like it has life. The name of this planet is
Answer: Earth.
3. Describe Earth’s axis.
Answer: Earth’s axis is an imaginary line that goes through Earth from the North Pole to the South Pole.
4. State whether each of the following statements is true or false.
a) Earth spins on its axis.
Answer: True.
b) Earth’s axis is slightly tipped, leaning to one side.
Answer: True.
5. Earth travels around the Sun at about
Answer: 67, 000 miles per hour (107, 000 kilometers per hour).
6. State whether each of the following statements is true or false.
a) One year is one trip around the Sun.
Answer: True.
b) Earth’s path around the Sun is slightly oval-shaped.
Answer: True.
7. What causes Earth’s distance from the Sun to change during the year?
Answer: The oval shape of Earth’s path around the Sun.
8. Explain the following observation in nature.
“The Sun seems to rise in the morning, cross the sky during the day, and set at night. However, the Sun does not actually move around the Earth.”
Answer: Earth’s turning on its axis makes it look as if the Sun is moving.
9. How long does Earth make a complete turn on its axis?
Answer: 24 hours.
10. State whether each of the following statements is true or false.
a) As Earth turns, half of the planet faces the Sun, and the other half faces away.
Answer: True.
b) It is daytime on the half of Earth facing the Sun and night on the half facing away from the Sun.
Answer: True.
11. Explain why Earth has seasons in the Northern and Southern Hemispheres.
Answer: Earth has seasons because of the tilt of its axis. For part of the year, the top half is tipped toward the Sun while the other half is tipped away from the Sun.
12. The top half of Earth is called the
Answer: Northern Hemisphere.
13. The bottom half of Earth is called the
Answer: Southern Hemisphere.
14. The half of Earth that is tipped toward the Sun experiences
Answer: summer.
15. The half of Earth that is tipped away from the Sun experiences
Answer: winter.
16. State whether each of the following statements is true or false.
a) When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere.
Answer: True.
b) During spring and fall, the hemispheres are tipped neither toward nor away from the Sun.
Answer: True.
17. What is the equator?
Answer: The equator is an imaginary line around Earth’s middle.
18. State whether each of the following statements is true or false.
a) The farther you are from the equator, the greater the difference in temperature between seasons.
b) The equator never tips far from the Sun.
Answer: True.
c) Near the equator it is warm enough to go swimming all year long.
Answer: True.
d) Near the equator, the average temperature barely changes from month to month.
Answer: True.
e) In Alaska, far from the equator, the average temperature in January can be more than 60 degrees colder than it is in July.
Answer: True.
19. Why is there life on Earth?
Answer: Earth has just the right conditions for life.
· It is not too hot or too cold.
· Earth has lots of liquid water.
· Earth has an atmosphere (gases) that can support life.
20. When did the first kinds of life appear on Earth? Approximately
Answer: 3.8 billion years ago. (3, 800, 0000 years ago)
21. State whether each of the following statements is true or false.
a) Several times during Earth’s history, almost all life went extinct or disappeared.
Answer: True.
b) Each time, some life forms survived.
Answer: True.
c) The survivors spread all over the planet.
Answer: True.
d) Dinosaurs appeared about 230 million years ago and went extinct about 65 million years ago.
Answer: True.
e) Scientists believe that modern humans appeared about 130, 000 years ago.
Answer: True.
22. The top layer of the Earth is called
Answer: crust.
23. What is the crust made of?
Answer: Hard rock and soil.
24. More than 70% of the Earth’s crust is covered with
Answer: water.
25. State whether each of the following statements is true or false.
a) Most of Earth’s water is salt water in the ocean.
Answer: True.
b) Pieces of dry land called continents rise above the ocean.
Answer: True.
c) The part of Earth’s crust under the ocean is called the
Answer: seafloor.
26. What is the mantle?
Answer: The mantle is a layer of partly melted rock under the Earth’s crust.
27. What is the Earth’s core?
Answer: The core is the layer of Earth under the mantle.
28. Earth’s core is mostly
Answer: iron.
29. a) The outer part of the Earth’s core is
Answer: liquid metal.
b) The inside of Earth’s core is
Answer: solid metal.
c) What creates Earth’s magnetic field?
Answer: Scientists believe that the liquid metal makes Earth a giant magnet and creates Earth’s magnetic field.
30. State whether each of the following statements is true or false.
a) Earth’s crust is made of gigantic slabs of rock called plates that move over the mantle.
Answer: True.
b) Plates crash together to make mountains.
Answer: True.
c) Plates pull apart and let red-hot rock ooze up from Earth to make new crust.
Answer: True.
31. How did Earth form?
Answer: Scientists think that Earth and the rest of the solar system formed from a spinning cloud of gas and dust.
32. State whether each of the following statements is true or false.
a) Gravity pulled most of the gas and dust together to form the Sun.
Answer: True.
b) Some leftover gas and dust formed the Earth and other planets.
Answer: True.
c) Scientists think that the Earth and the Moon formed about 4.6 billion years ago.
Answer: True.
33. What keeps the Earth and Moon near each other as they travel together around the Sun?
Answer: Gravity.
34. Earth is one of the planets that that circle around the Sun to form a solar system. What is so powerful that it can hold objects in orbit that are billions of miles away?
Answer: The Sun’s gravity.
35. After the Sun, the closest star to Earth is
Answer: Proxima Centauri.
36. Which star is more than 20 trillion miles (30 trillion kilometers) away?
Answer: Proxima Centauri.
37. a) How long does it take light from the Sun to reach Earth? Approximately
Answer: 8 minutes.
b) How long does it take light from Proxima Centauri to reach Earth? Approximately
Answer: 4.23 years.
38. How long does it take light from other stars which are so distant from the Earth to reach the Earth?
Answer: Billions of years.
39. The Sun joins about 400 billion others stars to form a galaxy called
Answer: The Milky Way.
40. What is shaped like a pinwheel, with curved arms that circle around the center?
Answer: The Milky Way Galaxy.
41. Where is the solar system located?
Answer: The solar system is located in one of the galaxy’s pinwheel arms out toward the edge of the galaxy.
42. The Milky Way Galaxy belongs to a cluster of about 30 galaxies called the
Answer: Local Group.
43. Within the Local Group, the closest galaxy to the Milky Way Galaxy is
Answer: The Andromeda Galaxy.
44. How long does it take light from Andromeda Galaxy to reach Earth? About
Answer: two million years.
45. State whether the following statement is true or false.
“Our universe is so large that scientists can only guess how far it stretches.”
Answer: True.
46. a) Earth’s atmosphere contains many layers. Name six of them.
Answer:
· Exosphere.
· Thermosphere.
· Mesosphere.
· Ozone layer.
· Stratosphere.
· Troposphere.
b) The closest layer of Earth’s atmosphere to Earth is the
Answer: troposphere.
c) Most of Earth’s weather occurs in the
Answer: troposphere.
d) The outermost layer of Earth’s atmosphere is the
Answer: exosphere.
e) Many satellites orbit the Earth in the
Answer: exosphere.
47. Life on Earth could not exist without energy from the
Answer: Sun.