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)

1
Q

Define:

Earth’s rotation

A

The spinning of Earth on its axis.

Earth’s rotation takes approximately 24 hours and is responsible for the cycle of day and night.

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2
Q

Define:

Earth’s revolution

A

The movement of Earth around the Sun.

Earth takes about 365.25 days to complete one revolution, which defines the length of a year.

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3
Q

Identify:

What is the imaginary line around which Earth rotates?

A

Earth’s axis

The axis is tilted at an angle of about 23.5 degrees, influencing seasonal changes.

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4
Q

Describe:

What happens during Earth’s rotation?

A

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.

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5
Q

Identify:

What imaginary line receives the most direct sunlight year-round?

A

The Equator

The Equator consistently gets nearly direct sunlight, leading to warm temperatures throughout the year.

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6
Q

Explain:

Why does Earth’s axial tilt affect the seasons?

A

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.

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7
Q

Explain:

What are the four main astronomical seasons?

A
  1. Spring
  2. Summer
  3. Autumn (Fall)
  4. 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.

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8
Q

True or False:

Earth is closest to the Sun during summer in the Northern Hemisphere.

A

False

Earth is actually closest to the Sun in early January, but seasons are determined by axial tilt, not proximity.

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9
Q

Identify:

When do day and night become nearly equal twice a year?

A

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.

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10
Q

Fill in the blank:

The longest and shortest days of the year are called the _______.

A

solstices

The summer solstice (June 20-21) has the longest daylight hours, while the winter solstice (December 21-22) has the shortest.

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11
Q

Explain:

Why do time zones exist?

A

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.

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12
Q

Define:

What is the Coriolis effect?

A

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.

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13
Q

Identify:

What is the reference point for global timekeeping?

A

The Prime Meridian (Greenwich Mean Time).

The Prime Meridian (0° longitude) is the standard reference for determining time zones worldwide.

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14
Q

Define:

leap year

A
  • 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.
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15
Q

Explain:

How does Earth’s motion affect day length?

A

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.

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16
Q

True or False:

All parts of Earth experience the same duration of daylight year-round.

A

False

The duration of daylight varies by latitude, with polar regions having extreme variations due to the axial tilt.

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17
Q

Define:

Sun-Earth-Moon system

A

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.

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18
Q

Identify:

What force keeps the Sun-Earth-Moon system together?

A

Gravity

Gravity controls the orbits of Earth around the Sun and the Moon around Earth.

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19
Q

Identify:

What is the point in Earth’s orbit closest to the Sun?

A

Perihelion

Perihelion occurs in early January when Earth is closest to the Sun, though its tilt, not distance, primarily determines seasonal temperatures.

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20
Q

Identify:

What is the point in Earth’s orbit farthest from the Sun?

A

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.

21
Q

Describe:

How does the Moon orbit Earth?

A

In an elliptical path.

The Moon’s orbit is slightly oval-shaped, causing variations in its distance from Earth.

22
Q

Explain:

Why do we always see the same side of the Moon from Earth?

A

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.

23
Q

Define:

lunar phase

A

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.

24
Q

Explain:

What are the eight phases of the Moon?

A
  1. New Moon
  2. Waxing Crescent
  3. First Quarter
  4. Waxing Gibbous
  5. Full Moon
  6. Waning Gibbous
  7. Last Quarter
  8. 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.

25
# Identify: What is the **phase** when the Moon is **completely illuminated**?
Full Moon ## Footnote This occurs when Earth is *between* the Sun and the Moon.
26
# True or False: A **supermoon** happens when the Moon is **closer** to Earth.
True ## Footnote A supermoon happens at **perigee**, when the Moon is closest to Earth, appearing up to 14% larger and 30% brighter than at apogee.
27
# Define: What is a **blue moon**?
A **second full moon** in a **single month**. ## Footnote Blue moons are **rare**, occurring roughly every 2.5 years due to differences between calendar months and the lunar cycle.
28
# Describe: What **happens** during a **solar eclipse**?
The Moon **blocks** sunlight, **casting a shadow** on Earth. ## Footnote This occurs when the Moon is between the Sun and Earth.
29
# Describe: What **happens** during a **lunar eclipse**?
Earth’s shadow **covers** the Moon. ## Footnote A lunar eclipse happens when Earth **blocks** sunlight from reaching the Moon, causing the Moon to pass through Earth’s shadow
30
# Explain: What are the **three types of solar eclipses**?
1. Total Solar Eclipse 2. Partial Solar Eclipse 3. Annular Solar Eclipse ## Footnote **Total Solar Eclipse** – The Moon completely blocks the Sun, casting a full shadow (umbra) on Earth. **Partial Solar Eclipse** – The Moon covers only part of the Sun, creating a partial shadow (penumbra). **Annular Solar Eclipse** – The Moon appears smaller than the Sun, leaving a bright ring (annulus) visible.
31
# Define: What is a **hybrid solar eclipse**?
An **eclipse that** **shifts** between total and annular. ## Footnote This **rare** event happens because Earth’s surface is curved, making different regions see different eclipse types.
32
# Explain: What are the **two types of lunar eclipses**?
1. Total Lunar Eclipse 2. Partial Lunar Eclipse ## Footnote **Total Lunar Eclipse** – The entire Moon is covered by Earth's shadow, turning it a reddish color. **Partial Lunar Eclipse** – Only a portion of the Moon enters Earth's shadow, causing a darkened section.
33
# Explain: Why don’t we see eclipses **every month**?
The Moon’s orbit is **tilted**, preventing perfect alignment. ## Footnote Its **5° tilt** relative to Earth’s orbit explains why eclipses don’t happen every month.
34
# Identify: What is the Sun’s **outer atmosphere** called?
The corona ## Footnote The **corona** is visible during a total solar eclipse and has extremely high temperatures.
35
# Define: tides
The **periodic rise** and **fall** of sea levels. ## Footnote Tides occur due to the gravitational pull of the **Moon** and, to a lesser extent, the **Sun**, causing regular fluctuations in sea levels.
36
# Explain: How does the **Moon** affect **Earth’s tides**?
Its gravity **pulls** on Earth's oceans, creating bulges of water. ## Footnote The Moon’s gravity pulls on Earth’s oceans, creating **tidal bulges**. As Earth rotates, different areas move through these bulges, resulting in **high** and **low tides** twice a day.
37
# Identify: What **type of tides** occur when the Sun, Moon, and Earth align?
Spring ## Footnote This results in **higher** high tides and **lower** low tides than normal.
38
# Identify: What is a region in the ocean with almost **no tidal movement**?
Amphidromic ## Footnote These points form due to *Earth's rotation*, *ocean basin shapes*, and the *Coriolis effect*, causing tides to rotate around them.
39
# Explain: Why are tides **stronger** during a **full moon**?
The Sun and Moon’s gravity **align**, increasing tidal force. ## Footnote This creates *spring tides*, which cause the highest and lowest tides.
40
# Identify: What are tides called that occur when the Sun and Moon are at **right angles**?
neap ## Footnote *Neap tides* occur when the Sun and Moon form a right angle with the Earth, reducing their combined gravitational pull. As a result, neap tides have the **smallest** difference between high and low tide, occurring during the first and third quarter moons.
41
# Explain: Why are there usually **two high tides** and **two low tides** daily?
Earth’s rotation **moves different areas** into the tidal bulges. ## Footnote This cycle repeats approximately every *12 hours*.
42
# Define: precession
The **slow wobble** of **Earth’s axis** over time. ## Footnote This motion gradually shifts *Earth's orientation* in space, impacting the alignment of stars over thousands of years.
43
# True or False: Precession **shifts the poles**, slowly changing Earth's seasons.
True ## Footnote Precession shifts the **timing** of solstices and equinoxes by slowly altering Earth’s orientation in space. Over thousands of years, this affects the calendar dates of seasons but does not significantly change seasonal climate patterns.
44
# Identify: What is the effect of **orbital changes** on **Earth's climate**?
They influence **ice ages** and **warming periods**. ## Footnote Changes in Earth's orbit, axial tilt, and wobble impact how sunlight is *distributed*, driving long-term climate cycles like *glacial* and *interglacial periods*.
45
# Identify: What is the **11-year cycle** of **solar activity** called?
The solar cycle ## Footnote The Sun goes through an 11-year cycle of increasing and decreasing **sunspots**, affecting space weather and sometimes Earth's climate.
46
# Explain: How do **solar flares** affect **Earth**?
They disrupt **satellites** and **power grids**. ## Footnote Solar flares release *bursts of radiation* that can interfere with communications, GPS, and even cause power outages when they interact with Earth’s magnetic field.
47
# Identify: What **natural phenomenon** is caused by **solar particles**?
Auroras ## Footnote When *charged particles* from the Sun hit Earth's atmosphere, they create colorful lights known as the *Northern* and *Southern Lights*, mainly seen near the poles.
48
# True or False: The Sun’s energy output is **always constant**.
False ## Footnote The Sun’s energy output *varies slightly* (~0.1%) over its 11-year solar cycle, affecting space weather and geomagnetic storms. While this can increase solar radiation and impact satellites, it does not drive major climate changes on Earth.