EARTH SCIENCE REGENTS REVIEW – QUIZ
ANSWERS:
Correct answers are bold, incorrect answers are gray.
1. The diagram below shows the Sun's maximum altitude (C) relative to a vertical stick in New
York State on June 21. In which direction from the base of the stick does shadow C' point?
1.
2.
3.
4.
north
south
east
west
The sun's maximum altitude occurs near noon. This high noon position always occurs in a
southerly direction in New York State. The shadow forms in the opposite direction and therefore
points north.
2. What is the exact shape of the Earth's orbit around the Sun?
1.
2.
3.
4.
The orbit is a slightly eccentric ellipse.
The orbit is a very eccentric ellipse.
The orbit is an oblate spheroid.
The orbit is a perfect circle.
The earth's orbit is very slightly elliptical. The sun is very near the center of this ellipse. In a
scale diagram, the orbit would look very much like a circle even though it is not a perfect circle.
3. The diagram below represents a planet orbiting a star. Lines are drawn from the star to four
positions of the planet. The amount of time required to move between positions is indicated.
Area X is equal to area Y. Why is the distance A-B greater than distance C-D?
1.
2.
3.
4.
The planet travels at a constant orbital velocity around the star.
The planet travels the same number of degrees per hour.
The length of a planet's day is the same throughout the year.
The planet's orbital velocity is dependent on its distance from the star.
The diagram illustrates one of Kepler's laws of planetary motion. It states that an orbiting planet
covers an equal area in an equal amount of time. From the diagram you can infer that the
distance between points A and B is greater than the distance between points C and D. The planet
is covering a greater distance between points A and B in the same amount of time. It must be
traveling at a greater velocity. In general, the velocity of a planet increases as it approaches a
star. The velocity of a planet decreases as it moves further away from the star.
4. During a period of one year, what would be the greatest altitude of the Sun at the North Pole?
1.
2.
3.
4.
90°
66½°
23½°
0°
Near March 21 the sun is directly overhead at the equator. The tilt of the earth's axis causes this
position to change during the year. Near June 21 the sun is directly overhead at 23½° north
latitude. At this time of year, the sun would appear to be highest in the sky to an observer at the
North Pole. The altitude of the sun at noon to this observer would be 23½°.
5. Which is the best evidence for the Earth's rotation?
1.
2.
3.
4.
the rising of the Sun
the changing of the seasons
the phases of the Moon
the motion of a Foucault pendulum
If the earth did not rotate on its axis, a freely swinging pendulum would follow a constant path.
The French scientist Jean Foucault first noted that the path of the pendulum changes. He
explained this by stating that the path of the pendulum was not changing. It only appeared to
change because the earth was rotating on its axis.
Wrong Choices Explained:
(1) The sun does appear to rise and set each day because of the earth's rotation. This could also
be explained by the sun traveling around the earth as was once believed.
(2) The changing of the seasons is related to the earth's orbit around the sun. This is an annual
pattern. It has no direct relationship to the earth's daily rotation.
(3) The phases of the moon are caused by the moon's revolution around the earth. This is a
monthly pattern caused by the relative positions of the earth, sun, and moon. It is not related to
the daily rotation of the earth about its axis.
6. Which motion causes the Moon to show phases when viewed from the Earth?
1.
2.
3.
4.
the rotation of the Moon on its axis
the revolution of the Moon around the Earth
the rotation of the Sun on its axis
the revolution of the Sun around the Moon
On a monthly basis the moon shows different phases because the relative positions of the earth,
moon, and sun are changing. As the moon approaches the opposite side from the earth and sun,
its face appears fully illuminated. This phase is called "full moon." When the moon approaches a
position between the earth and the sun, its face appears completely darkened. This phase is
known as "new moon." When the moon reaches other positions in its orbit around the earth,
different amounts of the surface appear to be illuminated.
7. In the diagram below, the direct rays of the Sun are striking the Earth's surface at 23½° N.
What is the date shown in the diagram?
1.
2.
3.
4.
March 21
June 21
September 23
December 21
As illustrated in the diagram, the earth's axis of rotation is inclined by 23½°. During the earth's
annual orbit around the sun the position of this axis relative to the orbit changes. On June 21 the
axis is pointed toward the sun. This is the condition illustrated in the diagram. By contrast on
December 21 the axis would appear pointed 23½° away from the sun.
8. New York State has several more hours of daylight in summer than in winter. Which
statement helps explain this observation?
1.
2.
3.
4.
The Earth is tilted on its axis.
The distance between the Earth and the Sun varies.
The diameter of the Sun appears to change.
The speed of the Earth in its orbit changes.
In New York State the number of hours of daylight varies during the year. During the summer
the sun's apparent path in the sky is higher than during the winter. As a result the number of
hours of daylight is greater during the summer. These differences are caused by the tilt in the
earth's axis.
Wrong Choices Explained:
(2) The earth is closest to the sun in December and farthest away in June. These differences do
not affect the number of hours of daylight.
(3) The diameter of the sun appears to change during the year. This occurs as the earth moves
closer or farther away from the sun. When the earth is closest to the sun, it appears to be largest.
This does not affect the number of hours of daylight.
(4) The speed of the earth around the sun increases as the earth moves closer to the sun. When
the earth is moving farther away from the sun, its speed in orbit decreases. These changes do not
affect the number of hours of daylight.
9. Based on observations made in the Northern Hemisphere, which statement is the best
supporting evidence that the Earth rotates on its axis?
1.
2.
3.
4.
The stars appear to follow daily circular paths around Polaris.
The apparent solar diameter varies throughout the year.
The length of the daylight period varies throughout the year.
The seasons (spring, summer, fall, and winter) repeat in a cyclic pattern.
The earth rotates on its axis. This axis extends through the poles. To an observer in the northern
hemisphere, the stars appear to be moving in a circular path during the night. We know from
other evidence that this is caused by the earth's rotation and not by the movement of stars.
10. On March 21, two observers, one at 45° north latitude and the other at 45° south latitude,
watch the "rising" Sun. In which direction(s) must they look?
1.
2.
3.
4.
Both observers must look westward.
Both observers must look eastward.
The observer at 45° N. must look westward while the other must look eastward.
The observer at 45° S. must look westward while the other must look eastward.
Each day the sun appears to rise in an easterly direction, travel across the sky and set in a
westerly direction. This is caused by the rotation of the earth. Since the whole earth is rotating in
the same direction, sunrise occurs in the same general direction everywhere. Actually the
northern observer would see the sun rise south of east. The southern observer would have to look
north of east for sunrise.
11. On December 21, at which latitude would an observer find the Sun directly overhead?
1.
2.
3.
4.
0°
23½° North
23½° South
90° South
The earth is tilted on its axis 23½°. As a result the sun is directly overhead at 23½° North on
June 21. It is directly overhead at the Equator on March 21 and September 21. On December 21
it is directly overhead at 23½° South.
12. Why do stars appear to move through the night sky at the rate of 15 degrees per hour?
1.
2.
3.
4.
The Earth actually moves around the Sun at a rate of 15° per hour.
The stars actually move around the center of the galaxy at a rate of 15° per hour.
The Earth actually rotates at a rate of 15° per hour.
The stars actually revolve around the Earth at a rate of 15° per hour.
The earth makes one complete rotation on its axis of 360° in 24 hours. Dividing 360° by 24
hours gives 15° per hour or the rate of rotation. This is the reason why the stars appear to move
through the sky at a rate of 15° per hour.
13. A sundial measures time based upon the position of the Sun in the sky. This time is called
1.
2.
3.
4.
apparent solar time
standard time
Greenwich time
mean time
Many years ago people measured time directly by the position of the sun in the sky. When the
sun was highest in the sky it was considered noon. This is an example of apparent solar time. To
avoid the confusion of different times at locations a few miles apart, we now use standard time
zones. It is considered noon at every point within that time zone even though the sun is not it its
highest position at all locations in that time zone.
DIRECTIONS: Base your answers to questions 14 through 18 on your knowledge of earth
science, the Earth Science Reference Tables, and the diagram below. The diagram is a model of
the orbit of an imaginary planet Q around a star. Points A, B, C, and D, indicate four orbital
positions of planet Q.
14. At which position in its orbit does planet Q have the greatest velocity?
1.
2.
3.
4.
A
B
C
D
When a planet follows an elliptical orbit its velocity increases as it approaches the star and
decreases as it moves farther away. At position C planet Q is closest to the star. At this position it
will have the greatest orbital velocity.
15. As planet Q moves from position A to position C, what change occurs in the gravitational
attraction between the star and planet Q?
1.
2.
3.
4.
The gravitational attraction becomes 1/25 as great.
The gravitational attraction becomes 5 times greater.
The gravitational attraction becomes 1/5 as great.
The gravitational attraction becomes 25 times greater.
When planet Q is in position A it is 5 times as far away from the star as it is when it is in position
C. You can determine this using the ruler in the Earth Science Reference Tables. Gravitational
attraction is inversely proportional to the square of the distance between the two objects. This
means that if the distance is reduced by half, the gravitational attraction becomes four times as
great. When the distance is reduced by 1/5 the gravitational attraction becomes 52 or 25 times as
great.
16. Which graph best approximates the gravitational force between the star and planet Q at
positions A through D?
(1)
(2)
(3)
(4)
The gravitational force between the star and the planet is greatest when they are closest together.
This force is least when they are farthest apart. Graph (2) shows the gravitational force to be
greatest in position C and lowest in position A. Planet Q is closest to the star in position C and
farthest away when it is in position A.
17. What is the approximate eccentricity of planet Q's orbit? [Use the Earth Science Reference
Tables.]
1. 0.06
2. 0.15
3. 0.67
4. 1.50
The eccentricity of the orbit can be calculated using the equation in the Earth Science Reference
Tables.
Eccentricity = distance between foci/length of major axis = 60mm/90mm = 0.67
Note that question 18 has only three choices.
18. How would a scale drawing of the Earth's orbit around the Sun compare to the scale drawing
shown of planet Q's orbit?
1. Earth's orbit would appear to have a more circular shape than planet Q's.
2. Earth's orbit would appear to have a more eccentric shape than planet Q's.
3. Earth's orbit would appear to be the same shape as Planet Q's.
The earth's orbit around the sun is very nearly circular. On a scale drawing this size the orbit
would in fact appear to be circular. The change in distance between the earth and the sun is less
than 3 million miles. When compared to the average distance of 93 million miles this difference
is very small.