4A1 The Sun-Earth-Moon System Flashcards
Explain how Earth's motions and its interactions with the Sun and Moon drive various environmental and atmospheric phenomena.
What is Earth’s rotation?
The spinning of Earth on its axis.
One full rotation takes approximately 24 hours and is responsible for the cycle of day and night.
How long does one complete rotation of Earth take?
Approximately 24 hours.
This is known as a solar day, which is about 23 hours, 56 minutes. The slight variation is due to Earth’s orbit, as it needs a bit more time to adjust for the movement in its orbit around the Sun.
What is Earth’s revolution?
The movement of Earth around the Sun.
Earth completes one revolution in about 365.25 days, which defines a year.
True or False:
Earth’s axis is perfectly perpendicular to its orbital plane.
False
Earth’s axis is tilted at approximately 23.5 degrees relative to its orbital plane.
What is the primary consequence of Earth’s axial tilt?
The changing of seasons.
The axial tilt causes variations in the angle and intensity of sunlight received at different latitudes throughout the year.
Define:
Solstices
The times when the Sun is at its highest or lowest point in the sky at noon.
Solstices occur twice a year, marking the longest and shortest days: the summer and winter solstices.
Fill in the blank:
The equinox occurs when day and night are nearly ______.
equal
During an equinox, the Sun is directly above the equator, leading to nearly 12 hours of daylight and darkness worldwide.
When do the equinoxes typically occur?
Around March 21st and September 23rd.
These are known as the vernal (spring) and autumnal (fall) equinoxes, respectively.
What causes Earth to experience day and night?
Earth’s rotation on its axis.
As Earth rotates, different parts of its surface move into and out of sunlight, creating day and night cycles.
True or False:
The Earth’s revolution affects the length of a day.
False
The Earth’s revolution primarily determines the length of a year, while rotation determines the length of a day.
What is the term for the path Earth follows during its revolution?
Orbit
Earth’s orbit is elliptical, meaning it is not a perfect circle but slightly oval-shaped.
Fill in the blank:
The tilt of Earth’s axis is approximately ______ degrees.
23.5
This tilt is responsible for seasonal variations in sunlight and temperature.
What is the main reason for the seasons on Earth?
The tilt of Earth’s axis combined with its revolution around the Sun.
Seasonal changes result from the varying angles of sunlight caused by axial tilt.
True or False:
The Earth’s speed of rotation is constant at all latitudes.
False
The speed of rotation is fastest at the equator and decreases toward the poles due to Earth’s spherical shape.
What is the significance of the Tropic of Cancer and the Tropic of Capricorn?
They mark latitudes where the Sun is directly overhead during solstices.
The Sun is overhead at the Tropic of Cancer during the summer solstice and at the Tropic of Capricorn during the winter solstice.
Fill in the blank:
Earth’s elliptical orbit causes the Sun’s apparent size to ______ throughout the year.
vary
The Sun appears slightly larger during perihelion and smaller during aphelion due to the varying distance.
What are periods of continuous darkness at the poles during winter?
Polar nights
Polar nights occur because the tilted axis prevents sunlight from reaching certain latitudes during winter months.
What are midnight suns?
Periods of continuous daylight at the poles during summer.
Midnight suns occur because the tilt of Earth’s axis allows continuous sunlight at high latitudes during summer months.
What is the significance of the Arctic and Antarctic Circles?
They define the boundaries of polar day and night.
Areas within these circles experience at least one day of continuous daylight or darkness annually.
True or False:
Earth’s axial tilt remains constant over time.
False
Earth’s axial tilt changes very slowly over thousands of years due to gravitational interactions, a phenomenon called axial precession.
What is the slow wobble of Earth’s axis over time?
Axial precession
Axial precession alters Earth’s orientation relative to the Sun and affects long-term climate patterns.
How does Earth’s revolution change the apparent position of stars?
It causes stars to shift positions throughout the year.
As Earth orbits the Sun, different parts of the sky become visible at different times of the year. This shift in the apparent position of stars is due to Earth’s changing vantage point in its orbit.
Fill in the blank:
The angle of sunlight is _________ during summer, leading to warmer temperatures.
higher
A higher Sun angle means more concentrated sunlight and increased heating of the Earth’s surface.
Why is the equator consistently warm year-round?
It receives nearly direct sunlight year round.
The equator experiences minimal variation in sunlight angles due to its location.
True or False:
The Earth’s orbit is a perfect circle.
False
Earth’s orbit is elliptical, causing varying distances from the Sun during the year.
What happens during the summer solstice in the Northern Hemisphere?
It experiences the longest day of the year.
The North Pole is tilted toward the Sun, leading to maximum daylight hours.
True or False:
Earth’s tilt creates uneven energy distribution across latitudes.
True
The axial tilt causes varying sunlight angles, leading to different climate zones.
Fill in the blank:
Earth’s motions drive __________, condensation, and precipitation.
evaporation
Earth’s rotation and revolution affect solar heating, which drives evaporation. Condensation and precipitation, however, depend on additional atmospheric conditions, such as temperature, humidity, and air pressure.
What causes tides on Earth?
The gravitational pull of the Moon and Sun.
The Moon’s gravity has the most significant effect on tides, but the Sun’s gravity also plays a role, though to a lesser extent.
What is a tidal cycle?
The rise and fall of sea levels caused by the Moon and Sun’s gravity.
A full tidal cycle consists of two high tides and two low tides over approximately 24 hours and 50 minutes.
True or False:
Tides occur only once per day.
False
Most coastal areas experience two high tides and two low tides daily, known as a semidiurnal tide cycle.
What is a spring tide?
A tide that occurs when the Sun, Earth, and Moon are aligned.
Spring tides produce higher high tides and lower low tides and occur during the new moon and full moon phases.
What is a neap tide?
A tide that occurs when the Sun and Moon are at right angles.
Neap tides produce lower high tides and higher low tides and occur during the first and third quarter moon phases.
When do spring tides occur?
During the new moon and full moon phases.
During these phases, the Sun and Moon are aligned, enhancing their gravitational effect on Earth’s oceans.
True or False:
Neap tides have higher high tides compared to spring tides.
False
Neap tides have lower high tides compared to spring tides due to the weaker combined gravitational pull of the Sun and Moon.
What is the tidal range?
The difference in height between high tide and low tide.
The tidal range varies depending on the Moon’s and Sun’s relative positions to Earth.
Fill in the Blank:
A larger tidal range is associated with _______ tides.
Spring
Spring tides have a larger difference between high and low tides due to the combined gravitational effects of the aligned Sun, Earth, and Moon.
What is the primary cause of eclipses?
The alignment of the Earth, Moon, and Sun.
Eclipses occur when one of these bodies casts a shadow on another, caused by their relative positions.
What happens during a lunar eclipse?
The Earth blocks the Sun’s light, casting a shadow on the Moon.
Lunar eclipses are visible only at night in regions where the Moon is above the horizon during the alignment of Earth’s shadow.
When do solar eclipses occur?
During a new moon.
A solar eclipse happens when the Moon is positioned directly between Earth and the Sun, blocking the Sun’s light.
True or False:
A solar eclipse cannot be seen from any location on Earth.
False
A solar eclipse is visible only from specific areas on Earth where the Moon’s shadow falls, but it can always be seen from some location within the path of totality or partial shadow during the eclipse.
During which moon phases do lunar eclipses occur?
Full moon
Lunar eclipses occur when Earth’s shadow falls on the Moon, which only happens when the Moon is full.
True or False:
Lunar eclipses are visible only during the night.
True
Lunar eclipses occur when the Moon is on the opposite side of Earth from the Sun, making them visible at night.
What is the period of approximately 18 years after which eclipses repeat?
Saros cycle
The Saros cycle describes the pattern in which similar eclipses occur, as the Sun, Moon, and Earth return to the same relative positions.
What effect does a total lunar eclipse have on the Moon’s appearance?
The Moon appears reddish.
During a lunar eclipse, Earth’s atmosphere scatters shorter wavelengths of light, allowing red wavelengths to reach the Moon.
Fill in the Blank:
A total solar eclipse occurs when the Moon completely blocks the ______.
sun
In a total solar eclipse, the Moon is perfectly aligned to cover the Sun completely, casting a shadow on Earth.
What is the result of a partial solar eclipse?
Only part of the Sun is covered by the Moon.
During a partial solar eclipse, the Sun’s light is only blocked in certain areas, creating a crescent shape.
What phase of the Moon is required for a solar eclipse?
New Moon
Solar eclipses occur during the new moon phase, when the Moon is directly between Earth and the Sun.
What causes the phases of the Moon?
Its position relative to the Earth and Sun.
As the Moon orbits Earth, different portions of its illuminated side become visible from Earth, creating the phases.
Which phase occurs when the Moon is between Earth and the Sun?
New Moon
During the new moon, the side of the Moon illuminated by the Sun is facing away from Earth, making it invisible.
What is the phase that immediately follow the new moon?
Waxing Crescent
In this phase, a small sliver of the Moon becomes visible as it begins to move away from the Sun in the sky.
True or False:
The full moon occurs when the Moon is on the opposite side of Earth from the Sun.
True
During the full moon, the entire illuminated half of the Moon is visible from Earth.
Fill in the Blank:
The phase that occurs after the full moon is called the _______ _________.
Waning Gibbous
After the full moon, the Moon starts to wane, with the visible illuminated portion decreasing.
What is the Moon phase when it is three-quarters through its cycle?
Third Quarter
During the third quarter, half of the Moon’s visible surface is illuminated, and it is moving toward the new moon phase.
What phase occurs after the waxing gibbous?
Full Moon
As the Moon’s illumination continues to grow, it reaches the full moon phase, where the entire face is visible.
True or False:
A waxing crescent moon occurs after a waning gibbous.
False
The waxing crescent follows the new moon, while the waning gibbous follows the full moon.
How long does it take for the Moon to complete one full cycle of phases?
Approximately 29.5 days.
This is known as a lunar month, or synodic month, and marks the period it takes for the Moon to return to the same phase.
Fill in the Blank:
The phase in which the Moon is fully illuminated is called the ______ _______.
Full Moon
The full moon occurs when the Earth is between the Sun and the Moon, and the entire illuminated side of the Moon is visible from Earth.
What is a full moon that appears larger due to its proximity to Earth?
Supermoon
A supermoon occurs when the Moon is at its closest point to Earth in its orbit, called the perigee.
What happens during the First Quarter Moon?
Half of the Moon’s visible surface is illuminated.
The first quarter occurs when the Moon has completed about one-quarter of its orbit around Earth.
What is solar wind?
A stream of charged particles from the Sun.
Solar wind can affect Earth’s magnetosphere and cause various phenomena like auroras and geomagnetic storms.
What effect can solar wind have on communication satellites?
It can interfere with their signals and operation.
Solar wind can disrupt satellite communications by disturbing the electrical systems and signals.
Fill in the blank:
The interaction between solar wind and Earth’s magnetic field creates ________.
auroras
Solar wind particles interact with Earth’s magnetosphere, exciting atoms in the atmosphere, which results in the display of auroras.
True or False:
Solar wind can cause power outages.
True
Solar wind can induce geomagnetic storms that affect power grids and electronics, leading to blackouts.
What is the primary cause of auroras?
Solar wind interacting with Earth’s magnetic field.
The charged particles in solar wind collide with gases in Earth’s atmosphere, causing them to light up and create auroras.
Define:
Geomagnetic storm
A disturbance in Earth’s magnetic field caused by solar wind.
Geomagnetic storms can interfere with navigation systems, communications, and power systems.
What is the region around Earth affected by solar wind?
The magnetosphere.
The magnetosphere is the area where Earth’s magnetic field interacts with solar wind, protecting the planet from the full force of solar radiation.
What is a solar flare?
A sudden, intense burst of energy from the Sun’s surface.
Solar flares can release large amounts of radiation and energy, impacting satellites, communications, and power systems.
True or False:
The solar wind can only cause damage during solar flares.
False
Solar wind itself can cause disturbances, but solar flares can enhance these effects, leading to more intense phenomena.
How does solar wind affect GPS systems?
It can cause errors in signal reception and navigation.
Solar wind can interfere with GPS satellites, leading to incorrect positioning data due to disruptions in satellite signals.
