Solar System — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A new moon phase occurs when the Moon is completely dark as seen from Earth.
During a new moon, the Moon sits between Earth and the Sun, so its sunlit side faces away from us and its dark side faces Earth, making it invisible in the night sky.
2. During a solar eclipse, the Moon passes between the Sun and Earth, blocking sunlight.
A solar eclipse occurs when the Moon lines up directly between the Sun and Earth, casting its shadow on Earth's surface and temporarily blocking sunlight from reaching a small area.
3. The Moon's cycle from new moon to new moon takes about 29 days.
The Moon's full phase cycle (synodic month) takes about 29 days because it needs a little extra time beyond its 27-day orbit to return to the same position relative to the Sun.
4. A lunar eclipse happens when Earth's shadow falls on the Moon.
During a lunar eclipse, Earth passes directly between the Sun and the Moon, so Earth's shadow falls on the Moon and darkens it, sometimes turning it a reddish color.
5. The pull of the Moon's gravity on Earth's oceans causes the rise and fall of tides.
The Moon's gravitational pull tugs on Earth's oceans, causing the water to bulge toward the Moon on one side and away on the other, creating the daily rise and fall of tides.
6. When more of the Moon's sunlit side becomes visible each night, the Moon is said to be waxing.
"Waxing" means growing, so a waxing moon shows more of its sunlit side each night as it moves from new moon toward full moon.
7. A quarter moon appears when exactly half of the Moon's face is lit by the Sun.
A quarter moon looks half-lit to us, but it is called "quarter" because the Moon has completed one-quarter (or three-quarters) of its full orbit around Earth.
8. Earth's axis is an imaginary line running from the North Pole to the South Pole.
Earth's axis is the imaginary line from the North Pole to the South Pole that the planet spins around. Its 23.5-degree tilt is what gives us seasons.
9. The longest day of the year in the Northern Hemisphere is called the summer solstice.
The summer solstice (around June 21) is the longest day because Earth's axis tilts the Northern Hemisphere closest toward the Sun, giving it the most hours of daylight.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
New moon
→ The Moon's sunlit side faces away from Earth
Earth's shadow covers the Moon turning it reddish
Full moon
→ The entire sunlit half of the Moon faces Earth
The entire sunlit half of the Moon faces Earth
Solar eclipse
→ The Moon blocks the Sun's light from reaching Earth
The Moon blocks the Sun's light from reaching Earth
Lunar eclipse
→ Earth's shadow covers the Moon turning it reddish
The Moon's sunlit side faces away from Earth
Each event depends on the positions of the Sun, Moon, and Earth: during a new moon the sunlit side faces away so we see darkness; during a full moon we see the entire lit half; a solar eclipse occurs when the Moon blocks the Sun; a lunar eclipse occurs when Earth's shadow darkens the Moon, bending red light onto its surface.