Discussions for week 9/10/11
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26_Lecture_Outline.pptxChapter 26: The Solar System
© 2017 Pearson Education, Inc.
Chapter 26 Lecture
1
This lecture will help you understand:
The Solar System and Its Formation
The Sun
The Inner Planets
The Outer Planets
Earth's Moon
Failed Planet Formation
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The Solar System and Its Formation
The solar system consists of:
Sun
System of planets
Asteroids
Comets
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The Solar System and Its Formation
Planets are divided into two classes:
Inner planets:
Mercury
Venus
Earth
Mars
Outer planets:
Jupiter
Saturn
Uranus
Neptune
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The Solar System and Its Formation
The Nebular theory:
Theory that the Sun and planets formed together from a cloud of gas and dust—a nebula.
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The Solar System and Its Formation
Nebular theory formation:
Gravitation between materials in the cloud pulled it inward.
When pulled inward, spin increased in accord with the conservation of angular momentum.
The spinning cloud conformed to the shape of a spinning disk.
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The Solar System and Its Formation
Nebular theory formation:
The center of the disk is the protosun.
Away from the center, planetesimals formed.
Planetesimals accreted more matter to become planets.
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The Solar System and Its Formation CHECK YOUR NEIGHBOR
Which of the following orbits around the Sun?
Planets.
Comets.
Asteroids.
All of the above.
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D. All of the above.
The Solar System and Its Formation CHECK YOUR ANSWER
Which of the following orbits around the Sun?
Planets.
Comets.
Asteroids.
All of the above.
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D. All of the above.
The Solar System and Its Formation CHECK YOUR NEIGHBOR
As a nebula shrinks under the influence of gravity, it
spins slower.
spins faster.
loses its spin.
spins into a protosun.
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B. spins faster.
The Solar System and Its Formation CHECK YOUR ANSWER
As a nebula shrinks under the influence of gravity, it
spins slower.
spins faster.
loses its spin.
spins into a protosun.
Explanation:
In accordance with the conservation of angular momentum, as the radius of the nebula decreases, its spin rate increases (like a skater who pulls her arms inward in a spin).
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B. spins faster.
The Sun
Sun:
nearest star to Earth
composed of mostly hydrogen in the plasma phase
hydrogen is fused to helium by thermonuclear fusion in its core
4.5 million tons of mass are converted to energy each second
a tiny fraction of this energy reaches and sustains Earth
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The Sun CHECK YOUR NEIGHBOR
Strictly speaking, in every second that passes, the mass of the Sun
decreases.
remains constant.
increases.
reinvents itself.
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A. decreases.
The Sun CHECK YOUR ANSWER
Strictly speaking, in every second that passes, the mass of the Sun
decreases.
remains constant.
increases.
reinvents itself.
Explanation:
It is this decrease that bathes the solar system with radiant energy. Solar mass is converted to energy via the celebrated equation, E = mc2.
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A. decreases.
The Inner Planets
The inner planets—four nearest to the Sun composed of high-density solid rock:
Mercury
Venus
Earth
Mars
Orbital speeds of planets around the Sun decrease with increasing distance from the Sun.
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The Inner Planets
Mercury:
closest to the Sun
slightly larger than our Moon
almost no atmosphere due to small size
daytime is long and hot (up to 430ºC)
nighttime is long and cold (about –170ºC)
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The Inner Planets
Venus:
next closest to the Sun
diameter about 0.95 that of Earth
very dense atmosphere, mostly carbon dioxide
volcanically active
very harsh place
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The Inner Planets
Earth:
third planet from the Sun—our home
at a distance where most of its water is neither solid nor gas, but liquid
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The Inner Planets
Mars:
fourth planet from the Sun—a potential away-from-home habitat
little more than half Earth's size
thin atmosphere—95% carbon dioxide and 0.15% oxygen (A planet with a thin atmosphere is ineffective in reducing the temperature difference between day and night!)
equatorial temperatures range from 30ºC in day to –130ºC at night
presently the focus of planetary exploration
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The Inner Planets
Mars:
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The Outer Planets
Outer planets:
gaseous, low-density worlds
appreciably larger than Earth
more widely spaced than the inner planets
in order of distance from Sun:
Jupiter
Saturn
Uranus
Neptune
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The Outer Planets
Jupiter:
first of the outer planets, beyond Mars
more than 11 times Earth's diameter—giant of the solar system
composition more liquid than gaseous or solid
atmospheric pressure more than a million times that of Earth's
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The Outer Planets
Jupiter:
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The Outer Planets
Jupiter:
atmosphere is 82% hydrogen, 17% helium, 1% methane, ammonia, and other molecules—cough!
no definite surface as occurs on the inner rocky planets
solid core of iron, nickel, and other minerals
Because of its thick atmospheric blanket, daytime and nighttime temperatures are about the same for equal altitudes above its "surface."
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The Outer Planets
Jupiter's four largest moons
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The Outer Planets
Jupiter's moon Europa has an ice-capped ocean, which may hold extraterrestrial life
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The Outer Planets
Saturn:
most remarkable for its easily seen rings
twice as far from Earth as Jupiter
diameter about ten times that of Earth, excluding the rings
lowest density of all planets—could float in giant bathtub (density is less than that of water)
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The Outer Planets
Saturn:
surrounded by rings—hypothesized to be bits of a moon never formed, or remnants of a moon torn apart by tidal forces
inner part of rings, like any satellite, travels faster than outer part of the ring system
Rocks that make up the rings orbit independently of other rocks.
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The Outer Planets
Saturn's largest moon, Titan, was visited by the Cassini spacecraft.
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The Outer Planets
Uranus:
twice as far from Earth as Saturn is
diameter about four times that of Earth
98º tilt to the orbital plane— a most unusual feature
faint ring system
methane atmosphere
very cold place
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The Outer Planets
Neptune:
lies beyond Uranus
diameter almost four times that of Earth, somewhat smaller than Uranus
atmosphere mainly hydrogen and helium
highly elongated elliptical path about the Sun
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The Outer Planets
Pluto:
since 2006, classified as a dwarf planet
very unlike other planets in composition, size, and orbit
highly elliptical orbit, like comets
spends most of its orbital time well beyond Neptune, in the Kuiper Belt
composition like that of Kuiper-Belt objects
look-alike neighbors not classified as planets
former planetary status was more historical than astronomical
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The Outer Planets CHECK YOUR NEIGHBOR
Which planet is more dense than water?
Mars.
Venus.
Neptune.
All of the above.
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D. All of the above.
The Outer Planets CHECK YOUR ANSWER
Which planet is more dense than water?
Mars.
Venus.
Neptune.
All of the above.
Explanation:
Saturn is the only planet with a density less than that of water.
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D. All of the above.
Earth's Moon
Earth's Moon:
more is known about the Moon than any other celestial body
diameter about one quarter that of Earth
no atmosphere—no weather and erosion to conceal past scarring of its surface (wears no "makeup")
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Earth's Moon
Twelve people have stood on the Moon. Here we see Buzz Aldrin, one of the three Apollo 11 astronauts.
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Earth's Moon
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Earth's Moon
Phases of the Moon:
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Earth's Moon
The Moon spins about its polar axis as it revolves around Earth.
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Earth's Moon CHECK YOUR NEIGHBOR
During the time of a new Moon, the
Sun is between Earth and the Moon.
Moon is between the Sun and Earth.
Earth is between the Sun and the Moon.
None of the above.
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B. Moon is between the Sun and Earth.
Earth's Moon CHECK YOUR ANSWER
During the time of a new Moon, the
Sun is between Earth and the Moon.
Moon is between the Sun and Earth.
Earth is between the Sun and the Moon.
None of the above.
Explanation:
A new Moon is mainly in the daytime sky, between Earth and the Sun. When it is exactly between them, we have a solar eclipse.
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B. Moon is between the Sun and Earth.
Earth's Moon CHECK YOUR NEIGHBOR
During the time of a full Moon, the
Sun is between Earth and the Moon.
Moon is between the Sun and Earth.
Earth is between the Sun and the Moon.
None of the above.
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C. Earth is between the Sun and the Moon.
Earth's Moon CHECK YOUR ANSWER
During the time of a full Moon, the
Sun is between Earth and the Moon.
Moon is between the Sun and Earth.
Earth is between the Sun and the Moon.
None of the above.
Explanation:
A full Moon occurs when Earth is between the Sun and Moon, while in Earth's view, the hemisphere of the Moon is fully in sunshine. When Earth is exactly between the Sun and the Moon, we have a lunar eclipse.
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C. Earth is between the Sun and the Moon.
Earth's Moon
A magnetic compass aligns with a magnetic field.
Like a compass in a magnetic field, the Moon aligns with Earth's gravitational field.
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Earth's Moon
Eclipses occur when the Moon's shadow falls on part of Earth.
This is a solar eclipse.
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Earth's Moon
A lunar eclipse occurs when Earth's shadow falls on the Moon.
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Earth's Moon
Eclipse:
The red light of sunrises and sunsets all around Earth is refracted onto the Moon's surface during a lunar eclipse.
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Failed Planet Formation
Asteroids:
small rocky bodies that orbit the Sun
most are located between Mars and Jupiter
some encounter Earth
unnoticed on ground—conspicuous on ice (the reason many are found in Antarctica)
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Failed Planet Formation
Comets:
differ from asteroids in chemical composition
are masses of water, methane, and ice—dirty snowballs
most located in Kuiper Belt and Oort Cloud
highly elliptical (highly eccentric) orbital paths
tail of comets swept outward from Sun by solar wind
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Failed Planet Formation
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Failed Planet Formation CHECK YOUR NEIGHBOR
Asteroids are small rocky bodies that
orbit the Sun.
mainly reside between Mars and Jupiter.
are smaller than Earth's Moon.
All of the above.
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D. All of the above.
Failed Planet Formation CHECK YOUR ANSWER
Asteroids are small rocky bodies that
orbit the Sun.
mainly reside between Mars and Jupiter.
are smaller than Earth's Moon.
All of the above.
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D. All of the above.
Failed Planet Formation CHECK YOUR NEIGHBOR
The tails of comets point in a direction
toward the Sun.
away from the Sun.
at nearly right angles to the Sun.
None of the above.
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B. away from the Sun.
Failed Planet Formation CHECK YOUR ANSWER
The tails of comets point in a direction
toward the Sun.
away from the Sun.
at nearly right angles to the Sun.
None of the above.
Explanation:
The solar wind blows the tails in a direction away from the Sun.
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B. away from the Sun.
Failed Planet Formation
Meteoroids
are relatively small (sand-grain to boulder size) pieces of debris chipped off asteroids or comets
Meteor:
a meteoroid that strikes Earth’s atmosphere
often called a "falling star"
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Failed Planet Formation
Meteorite
a meteoroid that survives the trip through the atmosphere and reaches Earth's surface
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Failed Planet Formation CHECK YOUR NEIGHBOR
Which of these makes contact with Earth's surface?
Meteor.
Meteorite.
Meteoroid.
None of the above.
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B. Meteorite.
Failed Planet Formation CHECK YOUR ANSWER
Which of these makes contact with Earth's surface?
Meteor.
Meteorite.
Meteoroid.
None of the above.
Explanation:
A meteorite has changed its status from meteoroid to meteor to meteorite.
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B. Meteorite.
