Section 1: Planetary Motion
2. Kepler discovered that planets move faster when they
b. are closer to the sun
3. On what properties does the force of gravity between two objects depend?
Mass and distance
4. How does gravity keep a planet moving in an orbit around the sun?
The motion of a planet is a balance between falling toward the sun and moving in a straight line
past it. The result is a curved orbit around the sun.
Section 2: Days and Seasons on Earth
1. A solstice is the time at which the sun is farthest north or south of the equator.
2. A day is the time it takes the Earth to rotate once on its axis.
3. The time at which the North Pole is tilted toward the sun and the Northern Hemisphere receives more
daylight hours that the Southern Hemisphere is called
b. the June Solstice
4. What causes daylight and night on Earth?
Daylight and night are caused by the rotation of the Earth on its axis.
5. Sunlight travels through space to the Earth at a speed of 300,000km/s. The average distance between
the sun and Earth is 150 million kilometers. How long does it take light to travel from the sun to Earth?
150,000,000km / 300,000km/s = 500s / 60s = 8.3 min
6. If the Earth was not tilted, would we have seasons?
No because the northern and southern hemispheres would receive the same amount of sunlight
all year long.
Section 3: Lunar Cycles
1. An eclipse happens when the shadow of one celestial body falls on another body.
2. The different appearances of the moon that are due to its position changes are called phases.
3. When the sunlit part of the moon appears to get smaller, the moon is said to be
d. waning
4. The diameter of the moon is 3,475km. What is the moon’s radius?
3,475km/2 = 1737.5km
5. Explain why we always see the same side of the moon.
The moon’s rate of rotation is the same as its period of revolution.
6. Describe how the movement of the Earth and the moon’s orbit cause the phases of the moon.
The moon has phases because of its changing position relative to the Earth and the sun. As the
moon revolves around the Earth, varying amounts of sunlight reflect off of the moon’s surface.
Section 4: Tides, the Sun, and the Moon
2. Tides are at their highest during
a. spring tide
3. Which tides have minimum tidal range? Which tides have maximum tidal range?
Minimum = Neap Tides, Maximum = Spring Tides
4. What causes tidal ranges?
The combined forces of the sun and moon on Earth result in tidal ranges that vary based on the
positions of all three bodies.
5. If it takes 24 hours and 50 min for a spot on Earth that is facing the moon to rotate to face the moon
again, how many minutes does it take?
24h x 60min = 1440 min: 1440 min + 50 min = 1490 min
6. How many days pass between the minimum and the maximum of the tidal range in any given area?
Explain your answer.
7 days: Both spring and neap tides occur every 14 days. Neaps tides occur halfway between
spring tides.
7. Explain how the position of the moon relates to the occurrence of high and low tides.
High tides occur on the side of Earth facing the moon and on the opposite side. Low tides form
on the sides of the Earth that are not facing or opposite of the moon.