16 - The Sun-Earth-Moon System Flashcards
This deck covers Earth's motions, including rotation, revolution, and their effects on day/night, seasons, and time zones. It also explores the Sun-Earth-Moon system, including lunar phases, tides, eclipses, and solar activity's impact. (48 cards)
Define:
Earth’s rotation
The spinning of Earth on its axis.
Earth’s rotation takes approximately 24 hours and is responsible for the cycle of day and night.
Define:
Earth’s revolution
The movement of Earth around the Sun.
Earth takes about 365.25 days to complete one revolution, which defines the length of a year.
Identify:
What is the imaginary line around which Earth rotates?
Earth’s axis
The axis is tilted at an angle of about 23.5 degrees, influencing seasonal changes.
Describe:
What happens during Earth’s rotation?
Earth spins counterclockwise, causing the cycle of day and night.
As Earth rotates, different parts face the Sun, experiencing daylight, while others move into darkness, experiencing night.
Identify:
What imaginary line receives the most direct sunlight year-round?
The Equator
The Equator consistently gets nearly direct sunlight, leading to warm temperatures throughout the year.
Explain:
Why does Earth’s axial tilt affect the seasons?
It changes the intensity and angle of sunlight in different regions.
When a hemisphere is tilted toward the Sun, it experiences summer; when tilted away, it experiences winter.
Explain:
What are the four main astronomical seasons?
- Spring
- Summer
- Autumn (Fall)
- Winter
These events occur because Earth’s axis is tilted at 23.5° relative to its orbit.
Spring – Begins at the vernal equinox, with nearly equal day and night.
Summer – Starts at the summer solstice, the longest daylight period.
Autumn (Fall) – Begins at the autumnal equinox, balancing day and night.
Winter – Starts at the winter solstice, the shortest daylight period.
True or False:
Earth is closest to the Sun during summer in the Northern Hemisphere.
False
Earth is actually closest to the Sun in early January, but seasons are determined by axial tilt, not proximity.
Identify:
When do day and night become nearly equal twice a year?
During the equinoxes.
The vernal equinox (March 20-21) and autumnal equinox (September 22-23) occur when the Sun is directly over the Equator, resulting in nearly equal day and night lengths.
Fill in the blank:
The longest and shortest days of the year are called the _______.
solstices
The summer solstice (June 20-21) has the longest daylight hours, while the winter solstice (December 21-22) has the shortest.
Explain:
Why do time zones exist?
Because Earth rotates, creating different local times across the globe.
The world is divided into 24 time zones, each roughly 15 degrees of longitude apart.
Define:
What is the Coriolis effect?
The deflection of moving air and water due to Earth’s rotation.
The Coriolis effect causes winds and ocean currents to curve right in the Northern Hemisphere and left in the Southern Hemisphere.
Identify:
What is the reference point for global timekeeping?
The Prime Meridian (Greenwich Mean Time).
The Prime Meridian (0° longitude) is the standard reference for determining time zones worldwide.
Define:
leap year
- Leap years add an extra day (February 29th) to synchronize the calendar with Earth’s slightly longer than 365-day orbit.
- The Gregorian calendar dictates leap years as those divisible by 4, except for century years not divisible by 400.
Explain:
How does Earth’s motion affect day length?
It varies near the poles but stays constant at the Equator.
Near the poles, daylight can last 24 hours in summer or nearly disappear in winter due to Earth’s axial tilt.
True or False:
All parts of Earth experience the same duration of daylight year-round.
False
The duration of daylight varies by latitude, with polar regions having extreme variations due to the axial tilt.
Define:
Sun-Earth-Moon system
The gravitationally bound relationship between the Sun, Earth, and Moon.
This system governs motions like Earth’s orbit, the Moon’s phases, tides, and eclipses.
Identify:
What force keeps the Sun-Earth-Moon system together?
Gravity
Gravity controls the orbits of Earth around the Sun and the Moon around Earth.
Identify:
What is the point in Earth’s orbit closest to the Sun?
Perihelion
Perihelion occurs in early January when Earth is closest to the Sun, though its tilt, not distance, primarily determines seasonal temperatures.
Identify:
What is the point in Earth’s orbit farthest from the Sun?
Aphelion
Aphelion occurs in early July when Earth is farthest from the Sun, but summer still happens in the Northern Hemisphere due to Earth’s tilt.
Describe:
How does the Moon orbit Earth?
In an elliptical path.
The Moon’s orbit is slightly oval-shaped, causing variations in its distance from Earth.
Explain:
Why do we always see the same side of the Moon from Earth?
Because of synchronous rotation.
The Moon is tidally locked to Earth, meaning its rotation period (27.3 days) matches its orbital period around Earth. As a result, the same hemisphere of the Moon is always facing Earth, while the far side remains unseen from the surface.
Define:
lunar phase
The changing appearance of the Moon as seen from Earth.
The phases result from the Moon’s orbit around Earth and the reflection of sunlight.
Explain:
What are the eight phases of the Moon?
- New Moon
- Waxing Crescent
- First Quarter
- Waxing Gibbous
- Full Moon
- Waning Gibbous
- Last Quarter
- Waning Crescent
New Moon – The Moon is between Earth and the Sun, making it invisible.
Waxing Crescent – A thin sliver of the Moon starts becoming visible.
First Quarter – Half of the Moon is illuminated, appearing as a half-circle.
Waxing Gibbous – More than half of the Moon is visible as it nears fullness.
Full Moon – The entire face of the Moon is fully illuminated.
Waning Gibbous – The Moon starts decreasing in illumination after the Full Moon.
Last Quarter – Half of the Moon is visible again, but now in its waning phase.
Waning Crescent – A thin sliver remains before transitioning back to the New Moon.