17 - The Solar System and the Universe

Question 1

Define:

solar system

Answer 1

A system of planets and celestial bodies orbiting the Sun.

The solar system is a vast and dynamic system, where all objects are held together by gravity, and their movements are governed by gravitational forces.

Question 2

Explain:

What are the main components of the solar system?

Answer 2

• The Sun
• Eight planets
• Dwarf planets
• Moons
• Asteroids
• Comets
• Kuiper Belt & Oort Cloud

The Sun – The central star that provides heat and light.

Eight planets – Large celestial bodies orbiting the Sun, including Earth.

Dwarf planets – Smaller planetary bodies like Pluto that do not clear their orbits.

Moons – Natural satellites orbiting planets.

Asteroids – Rocky objects, mostly found in the asteroid belt between Mars and Jupiter.

Comets – Icy bodies that develop tails when approaching the Sun.

Kuiper Belt & Oort Cloud – Regions of icy objects beyond Neptune, home to comets and other small bodies.

Question 3

Identify:

What is a natural object in space called?

Answer 3

celestial body

Celestial bodies include stars, planets, moons, asteroids, and comets, all of which exist in space and follow physical laws such as gravity and orbital motion.

Question 4

Describe:

What are the key characteristics of the Sun?

Answer 4

A hot, massive ball of hydrogen and helium.

The Sun generates energy through nuclear fusion, converting hydrogen into helium, which produces the light and heat that sustain life on Earth.

Question 5

Explain:

Why do planets orbit the Sun?

Answer 5

Due to the Sun’s gravitational pull.

The Sun’s gravity pulls planets toward it, but their forward motion creates a balance, causing them to follow a stable orbit instead of falling into the Sun.

Question 6

Identify:

Who developed the laws of planetary motion?

Answer 6

Johannes Kepler

Kepler formulated three laws describing how planets orbit the Sun, explaining their speeds and distances.

Question 7

Explain:

What are Kepler’s three laws of planetary motion?

Answer 7

1. Law of Ellipses
2. Law of Equal Areas
3. Law of Harmonies

Law of Ellipses – Planets orbit the Sun in an elliptical path.

Law of Equal Areas – A planet moves faster when closer to the Sun and slower when farther away.

Law of Harmonies – The farther a planet is from the Sun, the longer its orbit takes.

Question 8

True or False:

The further a planet is from the Sun, the faster it moves.

Answer 8

False

Kepler’s second law states that planets move faster when closer to the Sun (perihelion) and slower when farther away (aphelion).

Question 9

Define:

orbital period

Answer 9

The time a planet takes to orbit the Sun once.

Kepler’s third law shows that planets farther from the Sun take longer to complete an orbit due to weaker gravitational forces.

Question 10

Fill in the blank:

A satellite at a higher altitude takes _____ time to orbit Earth than one in a lower orbit.

Answer 10

more

Kepler’s Third Law states that the farther an object is from its orbiting body, the longer its orbital period.

Question 11

Explain:

How does Newton’s law of gravity apply to the solar system?

Answer 11

It explains why planets stay in orbit.

The force of gravity between two objects depends on their masses and the distance between them, keeping planets in stable orbits around the Sun.

Question 12

Identify:

What theory explains the solar system’s formation from gas and dust?

Answer 12

The nebular hypothesis.

Gravity pulled the nebula inward, forming the Sun at its center while the remaining material flattened into a disk, eventually forming planets, moons, and other bodies.

Question 13

Explain:

What are the main stages of solar system formation?

Answer 13

• Nebula Collapse
• Protosun Formation
• Planetesimal Accretion
• Planet Formation

Nebula Collapse – A gas and dust cloud collapses, forming a spinning disk.

Protosun Formation – Matter gathers at the center, heats up, and fusion begins to form the Sun.

Planetesimal Accretion – Dust and gas form small solid bodies.

Planet Formation – Planetesimals collide and merge, creating protoplanets that become planets.

Question 14

Identify:

What is the process of small particles forming larger bodies?

Answer 14

Accretion

Accretion led to the gradual buildup of planetesimals, which merged to form planets.

Question 15

Explain:

Why do inner planets differ from outer planets?

Answer 15

Inner planets are rocky; outer planets are gaseous.

Higher temperatures near the Sun caused lighter gases to evaporate, leaving behind rocky material, while cooler regions allowed gas giants to retain thick atmospheres.

Question 16

Identify:

What is the largest planet in the solar system?

Answer 16

Jupiter

Jupiter is a gas giant with a massive atmosphere and a strong magnetic field, over 11 times wider than Earth.

Question 17

Fill in the blank:

The longest day on any planet in our solar system is found on ______.

Answer 17

Venus

Venus has a longer rotational period (day) than its orbital period (year). A day on Venus lasts 243 Earth days, while it takes 225 Earth days to orbit the Sun, making its day longer than its year.

Question 18

Explain:

Why is Pluto no longer classified as a planet?

Answer 18

Because it does not clear its orbit of other objects.

Pluto is classified as a dwarf planet by the International Astronomical Union (IAU), a distinction that separates it from the eight major planets.

Question 19

Describe:

What are the characteristics of terrestrial planets?

Answer 19

Rocky, dense, and have few moons.

Mercury, Venus, Earth, and Mars are terrestrial planets, with solid surfaces and metal-rich cores.

Question 20

True or False:

Gas giants formed closer to the Sun than terrestrial planets.

Answer 20

False

Gas giants formed in the colder outer regions, where low temperatures allowed gases like hydrogen and helium to accumulate.

Question 21

Explain:

What are the gas giants in the solar system?

Answer 21

• Jupiter
• Saturn
• Uranus
• Neptune

Jupiter – The largest planet, known for its Great Red Spot and powerful magnetic field.

Saturn – Famous for its striking rings and numerous moons, including Titan.

Uranus – A planet with a unique sideways tilt and faint ring system.

Neptune – The most distant gas giant, with intense winds and a deep blue appearance.

Question 22

Explain:

What are the main characteristics of the gas giants?

Answer 22

• Massive size
• Gaseous composition
• No solid surface
• Rings and moons

Massive size – These planets are significantly larger than Earth.

Gaseous composition – Their atmospheres are primarily made of hydrogen and helium, with complex weather systems.

No solid surface – They don’t have solid ground; instead, their gaseous layers merge into liquid and metallic layers deeper in.

Rings and moons – These planets have large ring systems (especially Saturn) and many moons.

Question 23

True or False:

Saturn’s moon Titan has lakes of liquid methane on its surface.

Answer 23

True

Titan, Saturn’s largest moon, has vast lakes and seas of liquid methane and ethane on its surface due to extremely cold temperatures.

Question 24

Explain:

Why does Venus have a thick atmosphere?

Answer 24

Due to a runaway greenhouse effect.

Venus’ thick CO₂ atmosphere traps heat, making it hotter than Mercury.

Question 25

# Define: dwarf planet

Answer 25

A **small planet** that does not clear its orbit. ## Footnote **Pluto** is a well-known example because it shares its orbit with other objects in the Kuiper Belt.

Question 26

# Identify: What is the **largest moon** in the **solar system**?

Answer 26

Ganymede ## Footnote **Ganymede**, Jupiter’s moon, is even *larger than Mercury* and has a magnetic field.

Question 27

# True or False: The Moon is **slowly drifting away** from Earth.

Answer 27

True ## Footnote The Moon is moving away from Earth at a rate of about *3.8 centimeters per year* due to tidal forces between Earth and the Moon.

Question 28

# Define: asteroids

Answer 28

**Rocky objects** mainly found in the asteroid belt. ## Footnote Asteroids are *remnants* from the early solar system, and their sizes can range from a few meters to hundreds of kilometers.

Question 29

# Fill in the blank: The region **containing most asteroids** in our solar system is the \_\_\_\_\_\_ \_\_\_\_\_.

Answer 29

Asteroid Belt ## Footnote The *asteroid belt* contains thousands of small, rocky bodies left over from the early solar system, mostly between the orbits of Mars and Jupiter.

Question 30

# Describe: How do **asteroid belts** form?

Answer 30

From **small rocky bodies** that **didn’t form** into a planet. ## Footnote The asteroid belt between *Mars and Jupiter* is a prime example. It consists of remnants from the early solar system that were *unable* to coalesce into a planet due to the gravitational influence of Jupiter.

Question 31

# True or False: The **largest asteroid** in the solar system is **Ceres**.

Answer 31

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

Question 32

# Fill in the blank: A small, icy body that **forms a tail** near the Sun is called a \_\_\_\_\_\_.

Answer 32

comet ## Footnote **Comets** are composed of *ice*, *dust*, and *rocky material*, and their orbits often take them far from the Sun.

Question 33

# Fill in the blank: The **region** beyond Neptune **containing icy bodies** is called the \_\_\_\_\_\_ \_\_\_\_\_.

Answer 33

Kuiper Belt ## Footnote The *Kuiper Belt* is home to icy objects, including dwarf planets like Pluto and short-period comets.

Question 34

# Explain: Why do comets **develop tails**?

Answer 34

Solar radiation **vaporizes** their ice. ## Footnote *Solar radiation* causes the comet's ice to sublimate, and solar wind pushes the gas and dust away, forming the tail.

Question 35

# Identify: What is a **spherical cloud of icy objects** surrounding the solar system?

Answer 35

The Oort Cloud ## Footnote The *Oort Cloud* is believed to be the source of *long-period comets*, extending far beyond the orbit of Pluto.

Question 36

# True or False: All moons **formed** with their planets.

Answer 36

False ## Footnote Some moons, like *Neptune’s Triton*, were captured by their *planets’ gravity*, likely from other regions of space.

Question 37

# Identify: What is the name of the **first artificial satellite** launched into space?

Answer 37

Sputnik 1 ## Footnote **Sputnik 1** was launched by the Soviet Union on *October 4, 1957*, marking the start of the space age.

Question 38

# Define: orbit

Answer 38

The **path** a celestial body follows around another. ## Footnote Orbits are caused by *gravitational forces* and can be circular or elliptical, depending on the body’s motion and distance.

Question 39

# Explain: What are the **main types of orbits**?

Answer 39

* Circular * Elliptical * Parabolic * Hyperbolic ## Footnote **Circular** – An orbit where the distance from the central body remains constant. **Elliptical** – An oval-shaped orbit, with varying distance from the central body. **Parabolic** – A one-time curved path, typically followed by comets. **Hyperbolic** – A fast, escaping trajectory from the central body’s gravity.

Question 40

# True or False: All **planets** in the solar system have **circular orbits**.

Answer 40

False ## Footnote Planetary orbits are *generally elliptical*, meaning they have a slight oval shape rather than being perfectly circular. While the orbits of some planets, like *Earth's*, are nearly circular, they all exhibit a small degree of eccentricity.

Question 41

# Explain: How do the **orbits of moons** differ from those of **planets**?

Answer 41

Moons orbit **planets**, while planets orbit **stars**. ## Footnote Moons often have more eccentric orbits and may be captured bodies that didn’t form with their parent planet.

Question 42

# Define: exoplanet

Answer 42

A planet orbiting a star **outside** our solar system. ## Footnote Exoplanets can vary widely in *size*, *composition*, and *orbital characteristics*, ranging from gas giants to rocky Earth-like planets.

Question 43

# Explain: How are **exoplanets detected**?

Answer 43

By measuring the **dimming of a star’s light** or **spectral shifts**. ## Footnote The *transit method* detects dimming when a planet crosses its star, while *radial velocity* measures the star's wobble due to gravitational pull.

Question 44

# True or False: All exoplanets are **similar** to the planets in our solar system.

Answer 44

False ## Footnote Exoplanets, which orbit stars outside our solar system, can vary greatly in *size*, *composition*, and *orbital characteristics*.

Question 45

# Identify: What is the **regular gravitational influence** between two bodies called?

Answer 45

Orbital resonance ## Footnote *Orbital resonance* occurs when two objects, such as moons and planets, exert *periodic gravitational forces* on each other, leading to synchronized orbits and influencing their motion over time.

Question 46

# True or False: Moons **always orbit** their planets in the **same plane**.

Answer 46

False ## Footnote Some moons have *inclined orbits* or *retrograde motion* compared to their planet’s equatorial plane.