Review Exam 2.pptx

7/28/2019 Review Exam 2.pptx

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ASTR 1301

Exam 2 Review


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The Nature of Light Light can be treated as both a wave or a particle. It has a

wave-particle duality. In a vacuum electromagnetic waves (or light) travel at a

constant speed, the speed of light c=3x108 m/s. All

forms of light (or electromagnetic radiation) travel at

this speed, gamma rays, x rays, uv light, visiblelight, IR light and radio waves.

The speed of light is a product of the wavelength and

frequency of the light, c = f

The frequency of light is largest for gamma rays, and it

decreases as one goes to x-rays, then uv, then

visible light, then IR, then radio waves have the

lowest frequencies.


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The energy of light is related to the frequency. Gamma rays

are the most energetic, then x-rays, then uv, then visible (violet,

indigo, blue, green, yellow, orange, red) light, then IR, then

radio waves have the least energy.

The wavelength of light has the opposite behavior. It is

longest for radio waves, and shortest for gamma-rays.

Light obeys an inverse square law. The amount of lightappears to decrease as you move further away

inversely proportional to the square of the distance.

Light 1/r2

This means if you move twice as far away the source appears 4

times fainter. Three times further away, 9 times fainter. Ten

times further away, 100 times fainter.


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An emission spectrum looks like a number of bright lines.

An absorption spectrum looks like a continuous spectrum

disrupted by dark lines.


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The peak of the spectrum of a star (the wavelength at which

the stars spectrum reaches its peak) tells us how hot it is.

This same wavelength determines the color of a star. This

means that blue stars are hottest, then yellow stars and red

stars are the coolest.


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Light obeys the Doppler effect. If a light source moves away

from us its wavelength gets longer. The amount it gets

longer by depends on its speed. Higher speed means larger

Doppler shifts. A light source moving towards us has itswavelength decreased in a similar way.


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You must understand the Bohr Model of the atom. This

explains why we see emission spectra and absorption

spectra. It predicts that light is emitted falls from an outer

orbit to an inner orbit. If the electron jumps from an innerorbit to an outer orbit that light is absorbed.


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The frequency of visible light falls

between that of

a) infrared waves and radio waves.

b) X-rays and cosmic rays.

c) ultraviolet waves and X-rays.d) short radio waves and long radio waves.

e) ultraviolet waves and radio waves.


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The frequency of visible light falls

between that of

a) infrared waves and radio waves.

b) X-rays and cosmic rays.

c) ultraviolet waves and X-rays.d) short radio waves and long radio waves.

e) ultraviolet waves and radio waves.


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Does this object appear

reddish or bluish?


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Does this object appear

reddish or bluish?


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Blackbody Radiation

Which star looks redder? Star A or Star B

Which star gives off more red light? Star A or Star B

Which star looks bluer? Star A or Star B

Which star gives off more blue light? Star A or Star B

Which star has the higher surface temperature?

Star A or Star B


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Blackbody Radiation






Star A or Star B


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Blackbody Radiation






Star A or Star B


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Blackbody Radiation






Star A or Star B


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Blackbody Radiation






Star A or Star B


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Blackbody Radiation






Star A or Star B


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Blackbody Radiation

Which star looks redder?

Star A , Star C, Same

Which star gives off more red light?


Which star looks bluer?


Which star gives off more blue light?

Star A, Star C, Same




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Blackbody Radiation












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Blackbody Radiation












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Blackbody Radiation












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Blackbody Radiation












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Blackbody Radiation












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Blackbody Radiation

Which star has the greater surface temperature?

Star A or Star D


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Blackbody Radiation

Which star has the greater surface temperature?

Star A or Star D


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Types of Spectra

HOT, DENSE

ENERGY

SOURCE

HOT, DENSE

ENERGY

SOURCE

LOW DENSITY

CLOUD

LOW DENSITY

CLOUD

I.

II.

III.

What type of spectra is produced in each situation above? Emission, absorption, or

continuous

Situation I -

Situation II -

Situation III -


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Types of Spectra

HOT, DENSE

ENERGY

SOURCE

HOT, DENSE

ENERGY

SOURCE

LOW DENSITY

CLOUD

LOW DENSITY

CLOUD

I.

II.

III.


continuous

Situation I - Continuous spectrum

Situation II -

Situation III -


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Types of Spectra

HOT, DENSE

ENERGY

SOURCE

HOT, DENSE

ENERGY

SOURCE

LOW DENSITY

CLOUD

LOW DENSITY

CLOUD

I.

II.

III.


continuous


Situation IIEmission spectrum

Situation III -


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Types of Spectra

HOT, DENSE

ENERGY

SOURCE

HOT, DENSE

ENERGY

SOURCE

LOW DENSITY

CLOUD

LOW DENSITY

CLOUD

I.

II.

III.


continuous


Situation IIEmission spectrum

Situation IIIAbsorption spectrum


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Infrared radiation differs from red light

in

a) intensity.

b) wavelength.

c) its speed in a vacuum.

d) [All of the above.]

e) [None of the above.]


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Infrared radiation differs from red light

in

a) intensity.

b) wavelength.

c) its speed in a vacuum.




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The frequency at which a star emits

the most light depends on the stars

a) distance from us.

b) brightness.

c) temperature.

d) eccentricity

e) velocity toward or away from us.


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The frequency at which a star emits

the most light depends on the stars

a) distance from us.

b) brightness.

c) temperature.

d) eccentricity

e) velocity toward or away from us.


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Light waves of greater frequency have

a) shorter wavelength.

b) longer wavelength.

c) [Either of the above; there is no direct

connection between frequency and

wavelength.]


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Light waves of greater frequency have

a) shorter wavelength.

b) longer wavelength.

c) [Either of the above; there is no direct

connection between frequency and

wavelength.]


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The solar spectrum is which of the

following?

a) An absorption spectrum.

b) A continuous spectrum.

c) An emission spectrum.




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The solar spectrum is which of the

following?

a) An absorption spectrum.

b) A continuous spectrum.

c) An emission spectrum.




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We can determine the elements in the

atmosphere of a star by examining

a) its color.

b) its absorption spectrum

c) the frequency at which it emits the most

energy.

d) its temperature.

e) its motion relative to us.


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We can determine the elements in the

atmosphere of a star by examining

a) its color.

b) its absorption spectrum

c) the frequency at which it emits the most

energy.

d) its temperature.

e) its motion relative to us.

Sound waves cannot travel in a


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vacuum. How, then, do radio waves

travel through interstellar space?

a) They are extra-powerful sound waves.

b) They are very high frequency sound waves.c) Radio waves are not sound waves at all.

d) The question is a trick, for radio waves do not

travel through interstellar space.e) Interstellar space is not a vacuum.



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Sound waves cannot travel in avacuum. How, then, do radio waves

travel through interstellar space?

a) They are extra-powerful sound waves.

b) They are very high frequency sound waves.

c) Radio waves are not sound waves at all.

d) The question is a trick, for radio waves do not

travel through interstellar space.e) Interstellar space is not a vacuum.

f


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The energy of a photon is directly

proportional to the lights

a) wavelength.

b) frequency.

c) velocity.

d) brightness.

h f h d l


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The energy of a photon is directly

proportional to the lights

a) wavelength.

b) frequency.

c) velocity.

d) brightness.

h h d l f h li h i


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In the Bohr model of the atom, light is

emitted from an atom when

a) An electron moves from an inner to an outer

orbit.

b) An atom gains energy.

c) An electron moves from an outer to an inner

orbit.

d) One element reacts with another.

e) [Both A and B above]

I h B h d l f h li h i


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In the Bohr model of the atom, light is

emitted from an atom when

a) An electron moves from an inner to an outer

orbit.

b) An atom gains energy.

c) An electron moves from an outer to an inner

orbit.

d) One element reacts with another.

e) [Both A and B above]

Th i i / l h h f


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The intensity/wavelength graph of a

blue-hot object peaks in the

a) infrared region.

b) red region.

c) yellow region.

d) ultraviolet region.

Th i i / l h h f


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The intensity/wavelength graph of a

blue-hot object peaks in the

a) infrared region.

b) red region.

c) yellow region.

d) ultraviolet region.

The emission spectrum produced by


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The emission spectrum produced bythe excited atoms of an element

contains wavelengths that area) the same for all elements.

b) characteristic of the particular element.

c) evenly distributed throughout the entire

visible spectrum.

d) different from the wavelengths in its

absorption spectrum.

e) [Both A and D above.]

The emission spectrum produced by


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The emission spectrum produced bythe excited atoms of an element

contains wavelengths that area) the same for all elements.

b) characteristic of the particular element.

c) evenly distributed throughout the entire

visible spectrum.

d) different from the wavelengths in its

absorption spectrum.

e) [Both A and D above.]

E h l t h it


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Each element has its own

characteristic spectrum because

a) the speed of light differs for each element.b) some elements are at a higher temperature than

others.

c) atoms combine to form molecules, releasingdifferent wavelengths depending on theelements involved.

d) electron energy levels are different for differentelements.

e) hot solids, such as tungsten, emit a continuousspectrum.


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Th b t it f ti l t l i


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The best site for an optical telescope is

a place where the air is

a) thin and dry.

b) thick and dry.

c) thin and moist.

d) thick and moist.

Th b t it f ti l t l i


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The best site for an optical telescope is

a place where the air is

a) thin and dry.

b) thick and dry.

c) thin and moist.

d) thick and moist.

Whi h f th f ll i d t i th


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Which of the following determines the

light gathering power of a telescope?

a) The diameter of the objective.

b) The focal length of the objective.

c) The focal length of the eyepiece.

d) [Two of the above]



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light gathering power of a telescope?







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resolving power of a telescope?







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resolving power of a telescope?







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magnifying power of a telescope?







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magnifying power of a telescope?





The resolving power of a telescope is a


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measure of its

a) magnification under good conditions.

b) overall quality.

c) ability to distinguish details in an object.




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measure of its

a) magnification under good conditions.

b) overall quality.

c) ability to distinguish details in an object.


What power of a telescope increases


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the angular size of an object?

a) magnifying power

b) light gathering power

c) resolving power



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the angular size of an object?

a) magnifying power

b) light gathering power

c) resolving power


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The Arecibo telescope is

a) A large ground-based optical telescope.

b) An orbiting optical telescope.

c) A single radio telescope.

d) An array of radio telescopes

e) An orbiting infrared telescope.


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The Arecibo telescope is

a) A large ground-based optical telescope.

b) An orbiting optical telescope.

c) A single radio telescope.

d) An array of radio telescopes

e) An orbiting infrared telescope.

Th S l S t d Pl t


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The Solar System and Planets

You must know the order of the Planets from the Sun:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

You must know the definition of a Planet:

(a) A planet orbits the Sun

(b) A planet has sufficient mass for its self-gravity to overcome

rigid body forces so that it has a nearly-round shape

(c) A planet has cleared the neighborhood around its orbit

Escape velocity is the minimum speed required to escape the

gravitational force of a body such as a planet

Jupiter is the largest and most massive planet


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Jupiter is the largest and most massive planet

Mercury is the smallest and least massive planet

Pluto is no longer considered a planet. It is a Kuiper BeltObject or Dwarf Planet.

All planets revolve around the Sun in a counter-clockwise

direction. They all orbit very close to a path or plane that

we call the ecliptic.

The inner four planets (terrestrial planets) are mainly made of

rocky material, and have higher densities than the outer

(Jovian) Planets. They generally have thinner atmospheres

than the Jovian planets.

The outer (Jovian) planets are mainly composed of gas

(mostly hydrogen and helium) and have smaller densities

that the inner (terrestrial planets). They have thicker

atmospheres than the Terrestrial planets.

The inner (terrestrial) planets are Mercury, Venus, Earth and Mars


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The outer (Jovian) planets are Jupiter, Saturn, Uranus and

Neptune.

There are two theories that try to explain the formation of

Planetary Systems.

1) Catastrophic Theories. These suggest that a catastrophic event

like the collision of two stars can lead to the formation of

planetary systems. However, this would be extremely rare, and

we wouldnt see many other Planetary Systems. We now know

of 150 planetary systems, so this is very unlikely.

2) Evolutionary theories. These suggest that planetary systems

form naturally out of a ball of gas and dust similar to what we

now call the Solar Nebula.

The outer (Jovian) planets tend to have many more moons than


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the inner planets. Also, all of the Jovian planets have ring

systems. They are larger than Terrestrial planets.

Only two inner (terrestrial) planets have moons. The Earth andMars. Mars has two small moons, Phobos and Deimos.

Terrestrial planets are smaller than Jovian planets

After the Sun and the planets, the rest of the stuff we see in the

solar system is essentially debris:

1) Asteroids are mainly found in the asteroid belt, although there

are some that cross Earths orbit and are potential hazards.

2) The Kuiper Belt contains rocky, icy worlds beyond the orbit of

Neptune.

3) Comets are thought to originate from the Kuiper Belt or the Oort

Cloud

The outer (Jovian) planets tend to have many more moons


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The outer (Jovian) planets tend to have many more moons

than the inner planets.

Only two inner (terrestrial) planets have moons. The Earth

and Mars. Mars has two small moons, Phobos and Deimos.

After the Sun and the planets, the rest of the stuff we see in

the solar system is essentially debris:

1) Asteroids are mainly found in the asteroid belt, althoughthere are some that cross Earths orbit and are potential

hazards.

2) The Kuiper Belt contains rocky, icy worlds beyond the orbit

of Neptune.

3) Comets are thought to originate from both the Kuiper Belt

and the Oort Cloud

4) Meteoroids are objects smaller than asteroids, that have


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4) Meteoroids are objects smaller than asteroids, that have

the potential to strike a planet or moon.

5) A Meteor is an object that burns up in the atmosphere of a

planet or moon. On the Earth, most of them completelyburn up without ever reaching the ground.

6) A meteorite is the remnant of a meteor that did manage to

make it all the way to the surface of a planet or moon.

Mercury


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Mercury

Mercury is the closest planet to the Sun. It is also the smallest of

all of the planets in the Solar System.

Mercurys surface is covered in impact craters. It has a very thin

atmosphere

Venus


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Venus

From Earth we cannot see the surface of Venus. We see only

cloud tops because Venus has a very thick atmospherecompared to the other terrestrial planets

Venus has a very thick atmosphere composed mainly of carbon

dioxide. This has resulted in a runaway greenhouse affect with

an average surface temperature of 867 Farenheit.

Venus appears to have a very young surface (about 500,000

years old) so we speculate that the surface of Venus was

almost completely recovered by volcanic activity about

500,000 years ago


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Mars


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Mars

Mars is the red planet. It is the 4th planet from the Sun.

Mars has the largest known volcano in the Solar System. This

volcano is known as Olympus Mons

Mars also has a very large canyon, Valles Marineris. Valles

Marineris is about 2500 miles long and would stretch all theway from L.A. to New York city.

There is evidence that suggest that water may have once flowed

across the surface of Mars. These days we have evidence that

indicates that there is frozen water (ice) beneath the surface ofMars.


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Jupiter


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Jupiter

Jupiter is the largest planet in the Solar System. It has more mass

than all of the rest of the planets combined.

Jupiter has a system of rings, although they are not as prominent

as Saturns rings

The visible surface on Jupiter is actually the top of itsatmosphere or the cloud tops. This atmosphere is mostly made

up of Hydrogen gas (as is the case of all the Jovian planets).

A feature in the cloud tops on Jupiter is the Great Red Spot. This

is a storm system which is twice the size of the Earth with windspeeds of more than 300 miles per hour.

The rotation rate of Jupiter varies across its surface as you move


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p y

from the poles to the equator. When different parts of a planet

have different speeds we call this effect differential rotation.

Jupiter has 67 moons, and that is more moons than any otherplanet in the Solar System.

Jupiters most prominent moons are the Gallilean Moons. In

order of their distance from Jupiter, the Gallilean Moons are Io,

Europa, Ganymede and Callisto.

Ganymede is the largest moon in the Solar System. It is larger

than Mercury.


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Saturn


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Saturn

Saturn is similar to Jupiter in many ways. It is slightly smaller

than Jupiter, and has an atmosphere composed mainly ofHydrogen.

Saturn is most famous for its prominent rings

Saturns rings are made up of ice particles and in the plane of the


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Saturn s rings are made up of ice particles and in the plane of the

Saturns equator.

The rings also exist within the planets Roche limit. The Roche

limit of a planet is the radius within which a moon cannot

form. Any particles within the Roche limit cannot come

together to form a moon due to tidal forces. Also, any moon

that crosses within the Roche limit will be torn apart by tidal

forces

Saturn has 47 known moons. Its largest moon is Titan. Titan has

an atmosphere that is composed mainly of nitrogen and

methane, and may be another place in the Solar System that

contains life.

Uranus and Neptune


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p

Uranus and Neptune are the 7th and 8th planets from the Sun

respectively

They both appear blue across most of their surface because

methane in their atmosphere is frozen and therefore absorbs

red light

Uranus Neptune

Pluto and Solar System Debris


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Pluto and Solar System Debris

Since the IAU defined a planet in 2006, Pluto has been demoted

to have status as a dwarf planet. Indeed Pluto has much in common with objects found in a belt in

the outer Solar System known as the Kuiper Belt (objects in

this belt are often called Kuiper Belt Objects). Indeed Plutos

orbit is contained within the Kuiper Belt, and is therefore aKuiper Belt Object.

The Kuiper Belt objects (including pluto) are composed of rock

and ice. This is a very similar composition to comets. It is

theorized that short period comets originate from the KuiperBelt. If two Kuiper Belt objects pass close to each other it is

possible for one to get knocked out of the Kuiper Belt and

become a comet. These comets take tens or hundreds of years

to orbit the Sun

Long period comets take thousands of years to orbit the Sun. It is


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theorized that these objects originate from a region in the

Solar System that is far beyond the orbit of Pluto. This region is

called the Oort Cloud. It contains rocky/icy objects that areremnants left over from the formation of the Solar System and

the planets.

It is theorized that most comets either originate from the Kuiper

Belt or the Oort Cloud.

There is a region of the Solar System between Mars and Jupiter


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that contains most of the asteroids in the Solar System, and it

is termed the Asteroid Belt.

The largest asteroid is Ceres and it is 600 miles (1000 km) indiameter.

The rest of the material in the solar system is termed meteoroids.


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As a comet passes through the Solar System its tail leaves a

stream of debris in its wake. This stream of debris is composed

of particles termed meteoroids. We therefore call this stream ameteoroid stream.

As the Earth passes through a meteoroid stream, these

meteoroids enter the Earths atmosphere at very high

velocities. When they enter the atmosphere they becomemeteors. This is the cause of a meteor shower

Meteoroids do not always exist in streams and so meteors can

enter the atmosphere at any time. Most of them are small

enough that they completely burn up in the atmosphere.

If a large enough meteor enters the atmosphere of a planet it


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can make its way all the way to the surface. It impacts the

surface and leaves behind a scar or impact crater (such as

meteor crater in Arizona). In this case the remnant of themeteor that struck the surface of the planet is called a

meteorite.

Whi h l t i t i ?


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Which planet is most massive?

a) Mercury.

b) Mars.

c) Earth.

d) Jupiter.

e) Saturn.



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a) Mercury.

b) Mars.

c) Earth.

d) Jupiter.

e) Saturn.

Which planet is least massive?


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a) Mercury.

b) Mars.

c) Earth.

d) Jupiter.

e) Saturn.



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a) Mercury.

b) Mars.

c) Earth.

d) Jupiter.

e) Saturn.

The object whose orbit is more


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j

eccentric than Mercurys is

a) Saturn

b) Earth.

c) Pluto.

d) Venus.

e) Neptune.

The object whose orbit is more


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eccentric than Mercurys is

a) Saturn

b) Earth.

c) Pluto.

d) Venus.

e) Neptune.

Saturn is one of the planets


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Saturn is one of the ____ planets.

a) Jovian

b) Terrestrial

c) Minor

d) Inferior

e) Dwarf

Saturn is one of the planets


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Saturn is one of the ____ planets.

a) Jovian

b) Terrestrial

c) Minor

d) Inferior

e) Dwarf

Mars is one of the planets


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Mars is one of the ____ planets.

a) Jovian

b) Terrestrial

c) Minor

d) Inferior

e) Dwarf

Mars is one of the planets


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Mars is one of the ____ planets.

a) Jovian

b) Terrestrial

c) Minor

d) Inferior

e) Dwarf

Pluto is one of the planets


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Pluto is one of the ____ planets.

a) Jovian

b) Terrestrial

c) Minor

d) Inferior

e) Dwarf

Pluto is one of the planets


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Pluto is one of the ____ planets.

a) Jovian

b) Terrestrial

c) Minor

d) Inferior

e) Dwarf

Compared to Jovian planets, terrestrial


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planets have a

a) more rocky composition.

b) lower density.

c) more rapid rotation.

d) larger size.

e) [More than one of the above.]

Compared to Jovian planets, terrestrial


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planets have a

a) more rocky composition.

b) lower density.

c) more rapid rotation.

d) larger size.

e) [More than one of the above.]

Which of the following statements is


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true of Jovian planets?

a) They have low average densities compared toterrestrial planets.

b) Their orbits are closer to the Sun than the

asteroids orbits.c) They have craters in old surfaces.

d) They have smaller diameters than terrestrialplanets do.

e) They have fewer satellites than terrestrialplanets do.

Which of the following statements is


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true of Jovian planets?

a) They have low average densities comparedto terrestrial planets.

b) Their orbits are closer to the Sun than the

asteroids orbits.c) They have craters in old surfaces.

d) They have smaller diameters than terrestrialplanets do.

e) They have fewer satellites than terrestrialplanets do.

If planetary systems are caused asproposed by the catastrophe theories


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proposed by the catastrophe theories,

there should be

a) many planetary systems besides ours.

b) few planetary systems besides ours.

c) [Neither of these; the theories would makeno predictions in this regard.]

If planetary systems are caused asproposed by the catastrophe theories


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proposed by the catastrophe theories,

there should be

a) many planetary systems besides ours.

b) few planetary systems besides ours.

c) [Neither of these; the theories would makeno predictions in this regard.]

A di t th l ti th i f l


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According to the evolutionary theories of solar

system formation, the outer planets contain much

more hydrogen and helium than the inner planets

because these elements

a) Never fell in near the Sun.b) Condensed quickly to liquids and solids and

remained far from the Sun.

c) Were blown away from the inner solar system by

the solar wind.

d) [Both A and B above.]

e) [All of the above.]

A di t th l ti th i f l


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According to the evolutionary theories of solar

system formation, the outer planets contain much

more hydrogen and helium than the inner planets

because these elements

a) Never fell in near the Sun.b) Condensed quickly to liquids and solids and

remained far from the Sun.

c) Were blown away from the inner solar system by

the solar wind.

d) [Both A and B above.]

Review Exam 2.pptx

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