The Sun-Earth-Moon System Flashcards

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Questions and Answers

What causes seasons to change?

The tilt of Earth's axis causes seasons to change.

The first day of fall in the Northern Hemisphere is indicated by the _________.

September Equinox

The Earth takes 365.25 days to do what?

Revolve around the Sun

Where is Earth's northern axis pointing on the first day of winter?

Away from the sun Signup and view all the answers

Why is Earth colder at the poles than at the equator?

Earth is colder at the poles than at the equator because the light at the poles is more spread out than light at the equator. Signup and view all the answers

What causes days and nights on Earth?

Earth's rotation causes days and nights on Earth. Signup and view all the answers

What is an equator?

An imaginary line that divides Earth into its northern and southern hemispheres. Signup and view all the answers

What is an equinox?

Day when Earth's axis is not leaning toward or away from the Sun. Signup and view all the answers

What is an orbit?

Path an object follows as it moves around another object. Signup and view all the answers

What is revolution?

Motion of an object around another object. Signup and view all the answers

What is rotation?

Spinning motion. Signup and view all the answers

What is a rotation axis?

Line on which an object rotates. Signup and view all the answers

What is a solstice?

Day when Earth's rotation axis is the most toward or away from the Sun. Signup and view all the answers

What are maria?

Large, dark, flat areas on the Moon. Signup and view all the answers

What is a phase?

Lit part of the Moon or a planet that can be seen from Earth. Signup and view all the answers

What is a waning phase?

Occurs when less of the Moon's near side is lit each night. Signup and view all the answers

What is a waxing phase?

Occurs when more of the Moon's near side is lit each night. Signup and view all the answers

What is a lunar eclipse?

Occurs when the Moon moves into Earth's shadow. Signup and view all the answers

What is penumbra?

Lighter, outer part of a shadow where light is partially blocked. Signup and view all the answers

What is a solar eclipse?

Occurs when the Moon's shadow appears on Earth's surface. Signup and view all the answers

What is a tide?

Daily rise and fall of sea level. Signup and view all the answers

What is umbra?

Central, darker part of a shadow where light is totally blocked. Signup and view all the answers

Sun's energy reaches Earth as _ and _.

light and thermal energy Signup and view all the answers

How long does it take Earth to make one revolution around the Sun?

365.25 days (one year) Signup and view all the answers

What force keeps the Earth revolving around the Sun?

The Sun's gravity keeps the Earth revolving around the Sun. Signup and view all the answers

Rotation is a _______ motion.

spinning Signup and view all the answers

One complete Earth rotation is called a _ and takes _ hours.

day, 24 Signup and view all the answers

Earth's rotation axis is always _______ in the same direction by the same amount.

tilted Signup and view all the answers

Earth's rotation makes objects in the sky appear to move from _ to _.

east, west Signup and view all the answers

The energy in a beam of sunlight is spread out more at the _ than at the _.

poles, equator Signup and view all the answers

Earth rotates in a (clockwise/______) direction.

counterclockwise Signup and view all the answers

If the gravity between Earth and the Sun somehow stopped, what would happen to Earth?

Earth would fly off into space in a straight line. Signup and view all the answers

Around what does the Earth revolve?

The Sun Signup and view all the answers

Where does the north end of Earth's rotation axis lean during the December Solstice?

Away from the sun Signup and view all the answers

Which season does the December Solstice mark in the Northern Hemisphere?

Winter Signup and view all the answers

Which season does the December Solstice mark in the Southern Hemisphere?

Summer Signup and view all the answers

Why are the temperatures cooler in the Northern Hemisphere during the time near the December Solstice?

Because the north end of Earth's rotation axis is leaning away from the Sun. Signup and view all the answers

What is true about the number of daylight hours during the March Equinox?

There are nearly 12 hours of daylight and 12 hours of darkness everywhere on Earth. Signup and view all the answers

Which season does the March Equinox mark in the Northern Hemisphere?

Spring Signup and view all the answers

Study Notes

Seasons and Earth's Movements

Seasons change due to the tilt of Earth's axis relative to its orbit around the Sun.
The September Equinox marks the first day of fall in the Northern Hemisphere.
Earth completes one revolution around the Sun in 365.25 days, which defines a year.

Earth's Rotation

On the first day of winter, Earth's northern axis points away from the Sun.
Days and nights are caused by Earth's rotation, which takes approximately 24 hours to complete one full turn.
The equator is the imaginary line dividing Earth into northern and southern hemispheres.

Equinoxes and Solstices

An equinox occurs when Earth's axis is not tilted toward or away from the Sun, resulting in nearly equal day and night.
A solstice is the day when Earth's rotation axis is at its maximum tilt toward or away from the Sun, indicating the start of summer or winter.

Moon Features and Phases

Maria are large, dark, flat areas on the Moon's surface.
The phases of the Moon refer to the illuminated portion visible from Earth, with waxing phases indicating increasing visibility and waning phases indicating decreasing visibility.

Eclipses

A lunar eclipse happens when the Moon enters Earth's shadow, while a solar eclipse occurs when the Moon casts its shadow on Earth.
The penumbra is the lighter, outer part of a shadow where partial light is blocked; the umbra is the central, darker part where light is completely blocked.

Tides and Energy

Tides are caused by the daily rise and fall of sea level influenced by the gravitational pull of the Moon and Sun.
Sun's energy reaches Earth primarily in the form of light and thermal energy, more concentrated at the equator than at the poles.

Earth's Stability and Directionality

The Sun's gravity is the force that keeps Earth in orbit around it; if this force ceased, Earth would move in a straight line away from the Sun.
Earth rotates counterclockwise, so celestial objects appear to move from east to west in the sky.

Seasonal Variations and Daylight

During the December Solstice, the northern axis leans away from the Sun, marking winter in the Northern Hemisphere and summer in the Southern Hemisphere.
Near the December Solstice, temperatures are cooler in the Northern Hemisphere due to reduced sunlight.
The March Equinox results in nearly equal hours of daylight and darkness worldwide; it marks the start of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.

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Description

Test your knowledge about the dynamics of the Sun-Earth-Moon system with these flashcards. Learn about the causes of seasons, equinoxes, and Earth's revolution around the Sun. Perfect for students looking to grasp key concepts in astronomy.