4A2 The Earth and The Solar System

Question 1

Define:

Solar system

Answer 1

A collection of the Sun, planets, moons, asteroids, comets, and other celestial bodies bound by gravity.

The Sun is the central star, with planets and smaller objects orbiting around it in elliptical paths.

Question 2

How many planets are in the solar system?

Answer 2

Eight

The planets, in order from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Question 3

How long ago did the solar system form?

Answer 3

About 4.6 billion years ago.

This age is determined through radiometric dating of meteorites and lunar samples.

Question 4

True or False:

The Sun contains over 99% of the solar system’s mass.

Answer 4

True

The Sun’s massive size allows it to dominate the solar system gravitationally.

Question 5

How many layers does the Sun have?

Answer 5

Six

The Sun has six main layers: three internal layers (core, radiative zone, convective zone) and three atmospheric layers (photosphere, chromosphere, corona).

Question 6

What is the solar nebula theory?

Answer 6

Theory that the solar system formed from a rotating gas and dust cloud.

This cloud, called the solar nebula, collapsed under gravity, leading to the formation of the Sun and the planets.

Question 7

What is a flat, rotating disk of gas and dust around a protostar?

Answer 7

Protoplanetary disk

This disk is where planets, moons, and other bodies form through accretion of material.

Question 8

Fill in the blank:

The Sun forms at the ______ of the protoplanetary disk.

Answer 8

center

The majority of the material in the collapsing nebula collects at the center, forming the Sun.

Question 9

True or False:

All planets in the solar system orbit in the same plane.

Answer 9

False

While most planets’ orbits lie close to a region known as the ecliptic plane, they are not perfectly aligned due to slight inclinations

Question 10

What are planetesimals?

Answer 10

Small, solid objects formed from clumped dust and gas.

Planetesimals are the building blocks of planets, growing through collisions and accumulation of material.

Question 11

How do terrestrial planets form?

Answer 11

By the accumulation of rocky materials.

In the inner disk, metals and silicates condense due to higher temperatures, creating rocky planets.

Question 12

True or False:

The planets formed before the Sun.

Answer 12

False

The Sun formed first as the central mass of the nebula, and planets formed later from the remaining material in the disk.

Question 13

What are the two main types of planets in the solar system?

Answer 13

• Terrestrial
• Gas giants

Terrestrial planets are rocky and dense, while gas giants are large and composed mainly of hydrogen and helium.

Question 14

Which planet has the longest orbital period?

Answer 14

Neptune

Neptune takes about 165 Earth years to complete one orbit around the Sun.

Question 15

True or False:

The gas giants in our solar system are mostly rock and metal.

Answer 15

False

The gas giants (Jupiter, Saturn, Uranus, and Neptune) are composed mostly of hydrogen, helium, and ice, rather than rock and metal.

Question 16

Which planet has the longest day?

Answer 16

Venus

Venus takes about 243 Earth days to complete one rotation on its axis, making its day longer than its year.

Question 17

True or False:

Mercury is the planet closest to the Sun.

Answer 17

True

Mercury orbits closest to the Sun, completing its revolution in just 88 Earth days.

Question 18

What is the largest planet in the solar system?

Answer 18

Jupiter

Jupiter is the largest planet with a diameter of about 142,984 km, and it is primarily composed of hydrogen and helium.

Question 19

Which planet is known as the red planet?

Answer 19

Mars

Mars is known as the red planet due to its reddish appearance, caused by iron oxide (rust) on its surface.

Question 20

Fill in the blank:

The planet _______ is known for its extreme tilt, causing its seasons to be very different from other planets.

Answer 20

Uranus

Uranus has an axial tilt of about 98 degrees, causing its poles to be in direct sunlight for many years at a time.

Question 21

True or False:

Jupiter is thought to have formed first among the planets.

Answer 21

True

Its massive size and strong gravity likely allowed it to dominate and shape the outer solar system.

Question 22

Fill in the blank:

A/an ______ planet is a planet that orbits outside the asteroid belt.

Answer 22

outer

The outer planets include Jupiter, Saturn, Uranus, and Neptune.

Question 23

What is the main composition of Saturn’s rings?

Answer 23

Ice and rock particles.

Saturn’s rings are made of billions of small particles of ice and rock that vary in size from tiny grains to large chunks.

Question 24

What is the shape of the planets’ orbits?

Answer 24

Elliptical

According to Kepler’s first law, planets move in elliptical orbits with the Sun at one of the foci.

Question 25

What is the **average orbital speed** of Earth around the Sun?

Answer 25

About 29.78 km/s. ## Footnote Earth moves at this speed to **maintain** its orbit around the Sun, balancing gravitational pull with inertia.

Question 26

# Fill in the blank: A planet **moves fastest** in its orbit at \_\_\_\_\_\_\_\_.

Answer 26

perihelion ## Footnote **Perihelion** is the point in a planet’s orbit where it is closest to the Sun and moves fastest.

Question 27

What is the **point** in a planet’s orbit where it is farthest from the Sun?

Answer 27

Aphelion ## Footnote **Aphelion** is the point in a planet’s orbit where it is farthest from the Sun and moves slowest.

Question 28

# Fill in the blank: The **distance** between Earth and the Sun is one ______ _______.

Answer 28

Astronomical Unit (AU) ## Footnote One **AU** represents the *average distance* between Earth and the Sun, serving as a fundamental measurement in **astronomy** to describe distances within our solar system.

Question 29

# Fill in the blank: The **distance** from Earth to the Sun is approximately \_\_\_\_\_ million miles.

Answer 29

93 ## Footnote This is also known as 1 Astronomical Unit (AU), a unit of measurement for distances within the solar system.

Question 30

What is the **primary composition** of the Sun?

Answer 30

Hydrogen and helium. ## Footnote These light elements **fuel** *nuclear fusion*, producing the Sun's energy.

Question 31

What role does **gravity** play in the formation of the solar system?

Answer 31

It **pulls material together** to form stars, planets, and other bodies. ## Footnote It is the *fundamental force* that drives the collapse of the nebula and the accretion of planetesimals.

Question 32

How does the Sun’s gravity **affect** the planets?

Answer 32

It **keeps** them in orbit. ## Footnote The Sun’s gravitational pull **prevents** the planets from flying off into space and maintains their orbital paths.

Question 33

# Define: Dwarf planet

Answer 33

An **object** that orbits the Sun, is nearly spherical, but hasn't cleared its orbital path of debris. ## Footnote Examples of dwarf planets include *Pluto*, *Eris*, and *Haumea*.

Question 34

Why are inner planets **smaller** than outer planets?

Answer 34

They formed in a **region** with less material and higher temperatures. ## Footnote The *inner disk* lacked the ices and gases abundant in the *cooler outer disk*.

Question 35

# Fill in the blank: The process of smaller objects **merging** to form larger ones is called _____.

Answer 35

accretion ## Footnote **Accretion** is the dominant mechanism by which planets and other bodies grow in size.

Question 36

What is the **frost line** in the solar system?

Answer 36

The **boundary** beyond which ices can condense. ## Footnote Located between Mars and Jupiter, it *divides* the rocky inner planets from the gas and ice giants.

Question 37

# Fill in the blanks: The asteroid belt lies **between** \_\_\_\_\_\_ and \_\_\_\_\_\_\_\_.

Answer 37

Mars ; Jupiter ## Footnote It is thought to be made of *leftover* planetesimals that never formed into a planet due to Jupiter's gravitational influence.

Question 38

What **causes** gas giants to form in the outer solar system?

Answer 38

The accumulation of **ices** and **gases** around a solid core. ## Footnote Lower temperatures in the outer disk allow volatile compounds to condense, leading to the formation of gas and ice giants.

Question 39

What lies **beyond** Neptune and contains icy bodies and dwarf planets?

Answer 39

The Kuiper Belt ## Footnote It is the source of many short-period comets and includes Pluto.

Question 40

What **surrounds the solar system** and is the source of long-period comets?

Answer 40

The Oort Cloud ## Footnote It is the source of long-period comets and marks the *outermost* boundary of the Sun's gravitational influence.

Question 41

# True or False: Comets are **made** of rock and metal.

Answer 41

False ## Footnote Comets are **primarily** composed of ice, dust, and organic compounds.

Question 42

# Fill in the blank: A \_\_\_\_\_\_\_ is a small icy body that orbits the Sun and **develops a tail** when heated.

Answer 42

comet ## Footnote **Comets** originate from the *Kuiper Belt* or *Oort Cloud*. When near the Sun, their ice vaporizes, forming a glowing coma and tail.

Question 43

# True or False: Comets are usually **located** within the asteroid belt.

Answer 43

False ## Footnote Comets are typically located in the **outer** solar system, far beyond the asteroid belt, in regions like the Kuiper Belt and Oort Cloud.

Question 44

What is the main **difference** between asteroids and comets?

Answer 44

**Asteroids** are made of metal and rock, **comets** of ice, dust, and rock. ## Footnote Asteroids typically reside in the asteroid belt between Mars and Jupiter, whereas comets are found in the outer solar system.

Question 45

What is the name of the **largest** known asteroid?

Answer 45

Ceres ## Footnote **Ceres** is also classified as a dwarf planet and is the largest object in the asteroid belt between Mars and Jupiter.

Question 46

# True or False The Sun's gravitational pull on the Moon is **stronger** than Earth's.

Answer 46

True ## Footnote The Sun’s gravity is much stronger because it is more **massive**, and it dominates the gravitational forces acting on the planets and moons.

Question 47

What is the **largest moon** in the solar system?

Answer 47

Ganymede ## Footnote **Ganymede** is a moon of Jupiter and is larger than the planet Mercury.

Question 48

Which planet has the **most moons** in the solar system?

Answer 48

Saturn ## Footnote **Saturn** has the most moons in the solar system with 146 confirmed moons as of late 2024; *Jupiter* follows with 95 moons.

Question 49

# True or False: The Moon is **classified** as a planet.

Answer 49

False ## Footnote The Moon is Earth's *natural satellite* and is not classified as a planet, as it orbits Earth and not the Sun.

Question 50

How **long** does it take for the Moon to orbit Earth?

Answer 50

About 27.3 days. ## Footnote This is the *sidereal month*, the time it takes for the Moon to **complete** one full orbit around Earth relative to the stars.

Question 51

What is another **term** for a moon that orbits a planet?

Answer 51

Satellite ## Footnote **Moons** are *natural satellites* that orbit planets, and some planets, like Jupiter, have many moons.

Question 52

# True or False: The Moon’s orbit is **tilted** by about 5 degrees relative to Earth’s orbit.

Answer 52

True ## Footnote The Moon’s orbital tilt causes **eclipses** to occur only when the paths of the Sun, Earth, and Moon align.

Question 53

What **causes** the phases of the Moon?

Answer 53

**Changing positions** of the Moon, Earth, and Sun. ## Footnote Different portions of the Moon’s lit side are **visible** as it orbits Earth, creating phases.

Question 54

List the **phases** of the Moon.

Answer 54

1. New Moon 1. Waxing Crescent 1. First Quarter 1. Waxing Gibbous 1. Full Moon 1. Waning Gibbous 1. Last Quarter 2. Waning Crescent ## Footnote 1. **New Moon** – The Moon is between Earth and the Sun, making it invisible from Earth. 1. **Waxing Crescent** – A thin crescent of the Moon becomes visible as it starts growing. 1. **First Quarter** – Half of the Moon is illuminated; it is 90° from the Sun in the sky. 1. **Waxing Gibbous** – More than half of the Moon is visible as it continues to grow toward a full moon. 1. **Full Moon** – The entire face of the Moon is fully illuminated as it is opposite the Sun. 1. **Waning Gibbous** – The illuminated portion begins to shrink after the full moon. 1. **Last Quarter** – Half of the Moon is lit again, but now it is decreasing in illumination. 1. **Waning Crescent** – A thin crescent remains visible as the Moon nears the next new moon phase.

Question 55

What is the **Moon phase** when the Moon is between Earth and the Sun?

Answer 55

New Moon ## Footnote During the *New Moon phase*, the side of the Moon **illuminated** by the Sun faces away from Earth, making it appear invisible from our perspective.

Question 56

What is the **Moon's cycle** from new moon to new moon called?

Answer 56

Synodic month. ## Footnote The *synodic month* lasts about 29.5 days and describes the Moon’s complete cycle of phases.

Question 57

# Define: lunar eclipse

Answer 57

Earth's shadow **covers** the Moon. ## Footnote This happens during a *full moon* when Earth aligns between the Sun and Moon.

Question 58

# True or False: A solar eclipse occurs when the Moon **blocks sunlight** from reaching Earth.

Answer 58

True ## Footnote A solar eclipse happens when the Moon is positioned between the Sun and Earth, casting a **shadow** on Earth.

Question 59

What is a **tide**?

Answer 59

The **rise** and **fall** of sea levels. ## Footnote Tides are caused by *Moon’s gravity* and Sun’s lesser influence.

Question 60

Why do we **experience** tides daily?

Answer 60

Earth's rotation and Moon’s gravity. ## Footnote The Moon’s gravitational pull creates **bulges** in Earth’s oceans, and as Earth rotates, different areas pass through these bulges, resulting in *two high tides* and *two low tides* approximately every 24 hours.

Question 61

# True or False: The Moon’s gravitational pull is the **only cause** of tides.

Answer 61

False ## Footnote While the Moon's gravity is the *primary cause*, the Sun's *gravitational pull* also influences tides, creating spring and neap tides depending on their alignment.

Question 62

What is the **difference** between neap tides and spring tides?

Answer 62

**Neap tides** have the smallest tidal range; **spring tides** have the largest. ## Footnote Neap tides happen during quarter moons when the Sun and Moon pull from different directions. Spring tides happen during full and new moons when the Sun and Moon pull together.

Question 63

# Define: axial tilt

Answer 63

Earth's **23.5° angle** relative to its orbital plane. ## Footnote Earth's axial tilt of 23.5° is responsible for the *changing seasons* as different parts of the planet receive varying amounts of sunlight throughout the year.

Question 64

What is the **summer solstice**?

Answer 64

The **longest day** of the year, around June 21. ## Footnote The summer solstice occurs when the *Northern Hemisphere* is most tilted toward the Sun, receiving the **most** direct sunlight.

Question 65

# True or False: Earth's **distance** from the Sun causes the seasons.

Answer 65

False ## Footnote Seasons are caused by Earth's *axial tilt*, not its distance from the Sun, which affects how sunlight reaches each hemisphere throughout the year.

Question 66

What is the **vernal equinox**?

Answer 66

The day with **nearly equal** daylight and night, around March 21. ## Footnote The vernal equinox marks the **start** of spring in the Northern Hemisphere when the Sun is directly above the equator.