Earth in Motion
What motion of Earth causes day and night?
Earth’s rotation on its axis.
Where does the Moon’s visible light come from?
Sunlight reflected from the Moon’s surface.
What type of eclipse happens when the Moon blocks our view of the Sun?
A solar eclipse.
The Big Dipper is a what?
constellation
About how many degrees is Earth’s axis tilted from perpendicular to its orbital plane?
23.5°
About how long does Earth take to complete one revolution around the Sun?
One year, or about 365 days.
Which phase occurs when the Moon’s entire visible face appears illuminated?
Full moon.
During a lunar eclipse, which object is between the Sun and the Moon?
Earth
What motion of Earth makes stars appear to move across the sky during one night?
Earth’s rotation.
When it is summer in the Northern Hemisphere, what season is it in the Southern Hemisphere?
Winter
The Sun appears to move from east to west. What motion causes this apparent movement?
Earth rotates from west to east.
More than half of the Moon’s visible face is illuminated, and the bright portion is shrinking. What phase is it?
Waning gibbous.
Which part of a shadow is lighter because the light is only partially blocked?
The penumbra.
What motion of Earth explains why we see different constellations in different seasons?
Earth’s revolution around the Sun.
Two pairs of seasons have uneven day and night, and two pairs of seasons have equal day and night. Name the two groups.
June & December - Solstice; Spring & Fall - Equinoxes
What is the difference between rotation and revolution?
Rotation is spinning on an axis. Revolution is orbiting another object.
Why do we see different phases as the Moon orbits Earth?
We see different portions of the Moon’s sunlit half.
During a solar eclipse, one observer is in the Moon’s umbra and another is in its penumbra. How do their views differ?
The observer in the umbra sees a total solar eclipse; the observer in the penumbra sees a partial solar eclipse
Why can observers in New Jersey and southern Brazil see different groups of stars?
Their different latitudes give them different views of the sky.
Why does direct sunlight heat a surface more strongly than sunlight striking at a low angle?
Direct sunlight concentrates the energy over a smaller area.
If Earth had no axial tilt but still rotated, would it still have day and night? Explain.
Yes. Rotation would still turn locations toward and away from the Sun.
A student says Earth’s shadow causes the Moon’s regular phases. Correct the statement.
Phases come from our changing view of the Moon’s sunlit half. Earth’s shadow causes a lunar eclipse.
Why doesn’t a solar eclipse happen every new moon?
The Moon’s orbit is tilted, so the Sun, Moon, and Earth usually do not line up closely enough.
Why can some star patterns remain visible throughout the year from certain locations?
They are close enough to the visible celestial pole that they never move below that location’s horizon.
A student says summer happens because Earth is closer to the Sun. What actually causes the seasons?
Earth’s tilt as it revolves around the Sun changes daylight hours and the angle of sunlight.