Solar System — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. In June the Northern Hemisphere is tilted toward the Sun. Why does this cause summer in the Northern Hemisphere?
A) Earth is closest to the Sun during June so it receives more heat energy.
B) The tilt causes sunlight to hit the Northern Hemisphere more directly, spreading more energy over less area.
C) The Sun burns hotter during the months of June, July, and August each year.
D) The Northern Hemisphere spins faster in summer which generates more heat from friction.
When the Northern Hemisphere tilts toward the Sun in June, sunlight hits it at a steeper angle, concentrating more energy over a smaller area. This direct sunlight heats the surface more efficiently, causing warmer summer temperatures.
2. Solar eclipses do not happen every month even though the Moon orbits Earth monthly. What best explains this?
A) The Moon is sometimes too far from Earth to block the Sun completely.
B) The Moon's orbital plane is tilted about five degrees from Earth's so it usually passes above or below the Sun's position.
C) The Sun moves out of alignment with the Moon for most months of the year.
D) Earth's atmosphere bends sunlight around the Moon most of the time.
The Moon's orbit is tilted about five degrees relative to Earth's orbit around the Sun, so most months the Moon passes slightly above or below the Sun's position in the sky rather than directly in front of it.
3. During a lunar eclipse the Moon often appears reddish instead of completely dark. What causes this red color?
A) The Moon's surface contains iron oxide which glows red when heated by the Sun.
B) Mars reflects red light onto the Moon during a lunar eclipse.
C) Earth's atmosphere bends red wavelengths of sunlight onto the Moon's surface.
D) The Moon produces a faint red glow from volcanic activity beneath its crust.
Earth's atmosphere acts like a prism during a lunar eclipse, bending longer red wavelengths of sunlight around the planet and onto the Moon's surface, which is why the Moon glows reddish instead of going completely dark.
4. A student notices that days are much longer in summer and shorter in winter. Which statement correctly explains this observation?
A) Earth spins more slowly in winter causing shorter periods of daylight.
B) The Sun rises and sets at different points on the horizon because of Earth's tilted axis.
C) Clouds block more sunlight in winter making the days seem shorter.
D) Earth's orbit is larger in winter so it takes longer for the Sun to appear.
Earth's tilted axis changes where the Sun rises and sets on the horizon throughout the year. In summer the Sun follows a higher, longer path across the sky, giving more daylight hours, while in winter it follows a lower, shorter path.
Part B: Fill in the Blank
Write the correct answer on each line.
1. An equinox is a day when daytime and nighttime are nearly equal in length, occurring in spring and fall.
An equinox occurs twice a year (around March 21 and September 22) when Earth's axis tilts neither toward nor away from the Sun, giving nearly equal hours of daylight and darkness everywhere.
2. The Moon always shows the same face to Earth because it rotates once for every orbit it completes.
The Moon is tidally locked, meaning it rotates on its axis in exactly the same time it takes to orbit Earth. This keeps the same face pointed toward us at all times.
3. During a waning crescent phase, the visible part of the Moon is getting smaller each night.
"Waning" means shrinking, so during a waning crescent the lit sliver of Moon gets smaller each night until it disappears into the next new moon.
4. The area of total darkness during a solar eclipse is called the umbra of the Moon's shadow.
The umbra is the darkest, central part of the Moon's shadow where sunlight is completely blocked. Only people standing within this narrow cone on Earth see a total solar eclipse.
5. Earth takes 365 days to complete one full revolution around the Sun.
Earth takes about 365.25 days to orbit the Sun once, which defines one year. The extra quarter-day adds up, so every four years we add a leap day (February 29) to stay in sync.