4A2 The Solar System Flashcards
Describe how the solar system's formation led to an organized structure around the Sun, with planets, moons, and other celestial bodies.
Define:
Solar system
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.
How long ago did the solar system form?
About 4.6 billion years ago.
This age is determined through radiometric dating of meteorites and lunar samples.
How many planets are in the solar system?
Eight
The planets, in order from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
What is the solar nebula theory?
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.
True or False:
The planets formed before the Sun.
False
The Sun formed first as the central mass of the nebula, and planets formed later from the remaining material in the disk.
What is a flat, rotating disk of gas and dust around a protostar?
Protoplanetary disk
This disk is where planets, moons, and other bodies form through accretion of material.
Fill in the blank:
The Sun forms at the ______ of the protoplanetary disk.
center
The majority of the material in the collapsing nebula collects at the center, forming the Sun.
What are planetesimals?
Small, solid objects formed from clumped dust and gas.
Planetesimals are the building blocks of planets, growing through collisions and accumulation of material.
How do terrestrial planets form?
By the accumulation of rocky materials.
In the inner disk, metals and silicates condense due to higher temperatures, creating rocky planets.
What causes gas giants to form in the outer solar system?
The accumulation of ices and gases around a solid core.
Lower temperatures in the outer disk allow volatile compounds to condense, leading to the formation of gas and ice giants.
True or False:
Jupiter is thought to have formed first among the planets.
True
Its massive size and strong gravity likely allowed it to dominate and shape the outer solar system.
What role does gravity play in the formation of the solar system?
It pulls material together to form stars, planets, and other bodies.
It is the fundamental force that drives the collapse of the nebula and the accretion of planetesimals.
What are the two main types of planets in the solar system?
- Terrestrial
- Gas giants
Terrestrial planets are rocky and dense, while gas giants are large and composed mainly of hydrogen and helium.
Fill in the blanks:
The asteroid belt lies between ______ and ________.
Mars ; Jupiter
It is thought to be made of leftover planetesimals that never formed into a planet due to Jupiter’s gravitational influence.
What lies beyond Neptune and contains icy bodies and dwarf planets?
The Kuiper Belt
It is the source of many short-period comets and includes Pluto.
What surrounds the solar system and is the source of long-period comets?
The Oort Cloud
It is the source of long-period comets and marks the outermost boundary of the Sun’s gravitational influence.
Why are inner planets smaller than outer planets?
They formed in a region with less material and higher temperatures.
The inner disk lacked the ices and gases abundant in the cooler outer disk.
Fill in the blank:
The process of smaller objects sticking together to form larger ones is called _________.
accretion
Accretion is the dominant mechanism by which planets and other bodies grow in size.
What is the frost line in the solar system?
The boundary beyond which ices can condense.
Located between Mars and Jupiter, it divides the rocky inner planets from the gas and ice giants.
True or False:
The Sun contains over 99% of the solar system’s mass.
True
The Sun’s massive size allows it to dominate the solar system gravitationally.
What is the primary composition of the Sun?
Hydrogen and helium.
These light elements fuel nuclear fusion, producing the Sun’s energy.
True or False:
Comets are made of rock and metal.
False
Comets are primarily composed of ice, dust, and organic compounds.
How many layers does the Sun have?
Six
The Sun has six main layers: three internal layers (core, radiative zone, convective zone) and three atmospheric layers (photosphere, chromosphere, corona).
What is the core of the Sun?
The innermost layer where nuclear fusion occurs.
The Sun’s core is where hydrogen atoms fuse into helium, releasing energy in the form of light and heat.
Define:
Nuclear fusion
The process in which hydrogen nuclei combine to form helium through a series of reactions.
This process powers the Sun and provides the energy it radiates into space.
True or False:
The Sun’s surface is called the photosphere.
True
The photosphere is the Sun’s visible surface, from which light is emitted.
Fill in the blank:
The Sun’s radiative zone is located between the core and ______ the convective zone.
below
The radiative zone transfers energy outward through radiation.
What happens in the Sun’s convective zone?
Energy is transferred outward.
Hot plasma rises toward the surface, cools, and sinks again, creating convection currents.
What is the chromosphere?
The layer above the photosphere that emits a reddish glow.
The chromosphere is visible during a solar eclipse and plays a role in emitting ultraviolet radiation.
What is the Sun’s corona?
The outermost layer of the Sun’s atmosphere.
The corona extends millions of kilometers into space and is visible during a total solar eclipse.
True or False:
The Sun’s corona is cooler than its photosphere.
False
The corona is much hotter, with temperatures reaching 1-3 million degrees Celsius, compared to 5,500°C at the photosphere.
Fill in the blank:
Sunspots are generally found in regions of _____ magnetic activity.
high
Strong magnetic fields inhibit convection, making sunspots cooler and darker than their surroundings.
True or False:
The Sun’s corona can be observed without a solar eclipse.
False
The corona is usually obscured by the Sun’s brightness, but it is visible during a solar eclipse.
What is the temperature of the Sun’s core?
Approximately 15 million degrees Celsius.
This extreme heat is necessary for nuclear fusion to occur.
What is the primary element fueling the Sun’s fusion process?
Hydrogen
Hydrogen fuses to form helium, releasing energy that powers the Sun.
What type of radiation is primarily emitted from the Sun’s surface?
Visible light
The Sun emits a spectrum of radiation, but visible light is the most prominent form we observe on Earth.
Fill in the blanks:
The Sun is made up of approximately _____ hydrogen and _____ helium.
75%; 24%
Hydrogen and helium make up the majority of the Sun’s composition, with trace amounts of heavier elements.
True or False:
The Sun’s luminosity remains constant over time.
False
The Sun’s luminosity can change due to variations in solar activity and its life cycle.
How are sunspots formed?
Through the Sun’s magnetic field disrupting convection.
Sunspots are cooler areas caused by magnetic fields that suppress the flow of hot gas from the interior.
What can sunspots tell scientists about the Sun’s activity?
They indicate areas of intense magnetic activity.
Sunspot numbers correlate with solar cycles, affecting space weather and solar radiation.
What is the shape of the planets’ orbits?
Elliptical
According to Kepler’s first law, planets move in elliptical orbits with the Sun at one of the foci.
What is Kepler’s second law of planetary motion?
A planet sweeps out equal areas in equal times.
This means that a planet moves faster when it is closer to the Sun and slower when farther away.
True or False:
Mercury is the planet closest to the Sun.
True
Mercury orbits closest to the Sun, completing its revolution in just 88 Earth days.
Fill in the blank:
A planet moves fastest in its orbit at ________.
perihelion
Perihelion is the point in a planet’s orbit where it is closest to the Sun and moves fastest.
What is the point in a planet’s orbit where it is farthest from the Sun?
Aphelion
Aphelion is the point in a planet’s orbit where it is farthest from the Sun and moves slowest.
How long does it take for the Moon to orbit Earth?
About 27.3 days.
This is the sidereal month, the time it takes for the Moon to complete one full orbit around Earth relative to the stars.
True or False:
The Moon’s orbit is tilted by about 5 degrees relative to Earth’s orbit.
True
The Moon’s orbital tilt causes eclipses to occur only when the paths of the Sun, Earth, and Moon align.
Fill in the blank:
The distance from Earth to the Sun is approximately _____ million miles.
93
This is also known as 1 Astronomical Unit (AU), a unit of measurement for distances within the solar system.
Which planet has the longest orbital period?
Neptune
Neptune takes about 165 Earth years to complete one orbit around the Sun.
How does the Sun’s gravity affect the planets?
It keeps them in orbit.
The Sun’s gravitational pull prevents the planets from flying off into space and maintains their orbital paths.
What is the Moon’s cycle from new moon to new moon called?
Synodic month.
The synodic month lasts about 29.5 days and describes the Moon’s complete cycle of phases.
True or False:
All planets in the solar system orbit in the same plane.
False
While most planets’ orbits lie close to a region known as the ecliptic plane, they are not perfectly aligned due to slight inclinations
What is the average orbital speed of Earth around the Sun?
About 29.78 km/s.
Earth moves at this speed to maintain its orbit around the Sun, balancing gravitational pull with inertia.
Fill in the blank:
The distance between Earth and the Sun is referred to as one ________.
Astronomical Unit
(AU)
One AU is approximately 93 million miles, the average distance from Earth to the Sun.
Which planet has the longest day?
Venus
Venus takes about 243 Earth days to complete one rotation on its axis, making its day longer than its year.
True or False
The Sun’s gravitational pull on the Moon is stronger than Earth’s.
True
The Sun’s gravity is much stronger because it is more massive, and it dominates the gravitational forces acting on the planets and moons.
What is the largest planet in the solar system?
Jupiter
Jupiter is the largest planet with a diameter of about 142,984 km, and it is primarily composed of hydrogen and helium.
True or False:
The Moon is classified as a planet.
False
The Moon is Earth’s natural satellite and is not classified as a planet, as it orbits Earth and not the Sun.
Fill in the blank:
A _______ is a small icy body that orbits the Sun, typically beyond Neptune.
comet
Comets are made of ice, dust, and rocky material and often have a visible tail when they approach the Sun due to solar radiation.
What is the main difference between asteroids and comets?
Asteroids are made of metal and rock, comets of ice, dust, and rock.
Asteroids typically reside in the asteroid belt between Mars and Jupiter, whereas comets are found in the outer solar system.
What is the name of the largest known asteroid?
Ceres
Ceres is also classified as a dwarf planet and is the largest object in the asteroid belt between Mars and Jupiter.
Which planet is known as the red planet?
Mars
Mars is known as the red planet due to its reddish appearance, caused by iron oxide (rust) on its surface.
True or False:
The gas giants in our solar system are all made primarily of rock and metal.
False
The gas giants (Jupiter, Saturn, Uranus, and Neptune) are composed mostly of hydrogen, helium, and ice, rather than rock and metal.
What is the largest moon in the solar system?
Ganymede
Ganymede is a moon of Jupiter and is larger than the planet Mercury.
Fill in the blank:
A/an ______ planet is a planet that orbits outside the asteroid belt.
outer
The outer planets include Jupiter, Saturn, Uranus, and Neptune.
What is the main composition of Saturn’s rings?
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.
Which planet has the most moons in the solar system?
Saturn
Saturn has the most moons in the solar system with 146 confirmed moons as of late 2024; Jupiter follows with 95 moons.
Define:
Dwarf planet
An object that orbits the Sun, is nearly spherical, but hasn’t cleared its orbital path of debris.
Examples of dwarf planets include Pluto, Eris, and Haumea.
True or False:
Comets are usually located within the asteroid belt.
False
Comets are typically located in the outer solar system, far beyond the asteroid belt, in regions like the Kuiper Belt and Oort Cloud.
Fill in the blank:
The planet _______ is known for its extreme tilt, causing its seasons to be very different from other planets.
Uranus
Uranus has an axial tilt of about 98 degrees, causing its poles to be in direct sunlight for many years at a time.
What is another term for a moon that orbits a planet?
Satellite
Moons are natural satellites that orbit planets, and some planets, like Jupiter, have many moons.
