Download Solar System Notes

THE SOLAR SYSTEM
This view of
the rising Earth
was seen by
the Apollo 11
astronauts
after they
entered orbit
around the
Moon. Earth is
just above the
lunar horizon
in this
photograph.
Ideas about the Solar System
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Geocentric
Heliocentric
Planetary Motion
The Geocentric Model
 Saw the solar system as spheres with attached
celestial bodies rotating around a fixed Earth.
 Planets rotated around the Earth in perfect
circles.
 Model grew out of the ideas that:
 Humans were at the center of a perfect
universe created just for them
 Time period when religious beliefs dominated
science
The Heliocentric Model
 Nicolas Copernicus
 1543 suggested that the Earth revolves around the Sun.
 In this model planets moved around the Sun in perfect circles at
different distances and at faster speeds the closer to the Sun a
planet was
 Tycho Brahe
 Made precise measurements of the Sun, Moon, planets, and
the stars.
 Johannes Kepler
 Found that the planets did not move in perfect circles.
 Planets move in the path of a ellipse.
Kepler’s Laws of Planetary
Motion
 Kepler’s First Law.
 Each planet moves in an orbit that has the shape of a ellipse,
with the Sun located at one focus
 Kepler’s Second Law
 Imaginary line between the Sun and a planet moves over equal
areas of the ellipse during equal time intervals
 The velocity of a planet varies as it is not always the same
distance from the focus
 Point where the planet comes closet to the Sun is the
perihelion and the point at which it is farthest from the Sun is
the aphelion
 There is a third law that we will not talk about
Kepler's first law describes the shape of planetary orbit as
an ellipse, which is exaggerated in this figure. The Sun is
located at one focus of the ellipse.
Kepler's second law. A line from the Sun to a planet at
point A sweeps over a certain area as the planet moves to
point B in a given time interval. A line from the Sun to a
planet at point C will sweep over the same area as the
planet moves to point D during the same time interval. The
time required to move from point A to point B is the same
as the time required to move from point C to point D, so
the planet moves faster in its orbit at perihelion.
Origin of the Solar System
Origins of Solar System
 Heliocentric model of the solar system
 Commonly the most accepted model of the solar system
 Protoplanet nebular model
 most accepted theory of the origin of the solar system
 “proto” = precursor, forming
Protoplanet Nebular Model
Stage Overview:
A. Starts with a nebula of gas, dust, and chemical elements
from previously existing stars
B. Nebula is pulled together by gravity, forming into the
protosun and protoplanets.
C. As the planets form, they revolve around the Sun in orbits
that are described by Kepler's laws of planetary motion
(A) The process starts with a nebula of gas, dust, and
chemical elements from previously existing stars.
(B) The nebula is pulled together by gravity,
collapsing into the protosun and protoplanets.
(C) As the planets form, they revolve around the Sun in
orbits that are described by Kepler's laws of planetary
motion.
Stage A
All the elements that made up the current
solar system were derived from stars that
disappeared billions of year ago, even
before our Sun was born.
Hydrogen fusion in the core of large stars
results in the formation of elements through
iron
Elements that are heavier that iron are
formed in rare supernova explosions of
dying massive stars
Stage B
All of the elements from Stage A began to
form large, slowly rotating nebula
Because of gravity, size of this nebula
begins to decrease, which increased its rate
of spin
This spinning nebula formed an accretion
disk (big, bulging disk of gases and
elements formed as nebula condense)
Accretion disk becames compressed into
protoplanets and a protosun
Stage C
Initial flare-up of the Sun from the
warming and condensing established
the protosun as a star and it became our
Sun.
 Between the orbits of Mars and Jupiter there is an Asteroid belt
that some think was formed by the breakup of a larger planet.
The Planets
DISTANCE
VERY LARGE!
Measured in light-years
The distance which a ray of light would
travel in one year
About 6,000,000,000,000 (6 trillion)
miles
186,000 miles per second
299 792 458 m / s
Intro
 The solar system consists of:
 A middle aged main sequence G type star called the
Sun
 8 planets
 5 Recognized Dwarf planets
 Nearly fifty moons
 Thousands of asteroids,
 Many comets revolving around it
 This is all held together by the force of gravitational
attraction
 Terrestrial planets are those which have a
composition very similar to the Earth’s composition
(composed mostly of rocky material with iron)
Mercury
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Innermost planet
Period of revolution is 88 days.
Rotation once every 59 days.
High kinetic energy of gas molecules and a low gravitational pull
Surface temperature 427OC (800OF)in the sunlight to –180OC (350OF)in the dark
 Surface covered with craters
 Presence of magnetic fields and high density so must have a
high iron content with at least a partial molten core
Mercury is close to the Sun and visible only briefly
before or after sunrise or sunset, showing phases.
Mercury actually appears much smaller in an orbit
that is not tilted as much as shown in this figure.
A photomosaic of Mercury made from pictures taken
by the Mariner 10 spacecraft. The surface of Mercury
is heavily cratered, looking much like the surface of
Earth's Moon. All the interior planets and the Moon
were bombarded early in the life of the solar system.
Venus
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Very bright in morning and evening sky.
revolves around the Sun once every 225 days.
Rotates on its axis once every 243 days.
Exhibits retrograde rotation where the rotation of the planet is
opposite its direct of revolution around the Sun and opposite
most other planets.
Average surface temperature is 480 OC (900 OF)
Atmospheric pressure approximately 100 times that experienced
on Earth.
Clouds and rain consisting of sulfuric acid.
No satellites and no magnetic field.
This is an image of an 8 km
(5 mile) high volcano on the
surface of Venus. The image
was created by a computer
using Magellan radar data,
simulating a viewpoint
elevation of 1.7 km (1 mile)
above the surface. The lava
flows extend for hundreds of
km across the fractured
plains shown in the
foreground. The simulated
colors are based on color
images recorded by the
Soviet Venera 13 and 14
spacecraft.
Mars
 Unique, bright reddish color which exhibits a swift retrograde
motion
 Revolves around the Sun in 687 days.
 Rotates on its axis once every 24 hours, 37 minutes
 Has an atmosphere
 A geologically active past and is divided into 4 provinces:
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Volcanic regions
Systems of canyons
Terraced plateaus near the poles
Flat regions pitted with impact craters.
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average temperature is –53 OC (-63 OF)
Atmosphere is 95% CO
Atmospheric pressure 0.6 percent of Earth’s atmospheric pressure
Two satellites
Deimos – 13 km across
Phobos – 22 km across
Both are thought to be captured asteroids
Surface picture
taken by the
Viking 1 lander
found reddish,
fine-grained
material, rocks
coated with a
reddish stain,
and groups of
blue-black
volcanic rocks.
A view of the surface of Mars taken by the Viking Orbiter 1
cameras. The scene shows three volcanoes that rise an average
of 17 km (about 11 mile) above the top of a 10 km (about 6 mile)
high ridge. Clouds can be seen in the upper portion of the
photograph, and haze is present in the valleys at the lower right.
Jupiter
 Largest of all planets
 Twice as massive as all other planets combined and
about 318 times as massive as the Earth.
 Radiates twice as much energy as it gets from the sun due
to slow gravitational compression
 Made mostly of hydrogen and helium with some rocky
substances
 A solid core with a radius of about 14,000 km (8,500 miles)
The interior structure of Jupiter.
Photos of Jupiter taken
by Voyager 1. (A) From
a distance of about 36
million km (about 22
million mi). (B) A closer
view, from the Great Red
Spot to the South Pole,
showing organized cloud
patterns. In general, dark
features are warmer, and
light features are colder.
The Great Red spot
soars about 25 km
(about 15 mi) above the
surrounding clouds and
is the coldest place on
the planet.
Jupiter
 Sixteen satellites – four are called Galilean moons as they were
discovered by Galileo in 1610
Io
Europa
Ganymede
Callisto
The four Galilean
moons pictured by
Voyager 1.
Clockwise from
upper left, Io,
Europa,
Ganymede, and
Callisto. Io and
Europa are about
the size of Earth's
Moon; Ganymede
and Callisto are
larger than
Mercury.
Saturn
 Slightly smaller and less massive than Jupiter with a system
of rings
 The rings are made up of particles, some which are meters
across and some that are dust sized particles.
 10 moons
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Janus
Mimas
Enceladus
Tethys
Dione
Rhea
Titan
Hyperion
Iapetus
Phoebe
 Titan is the only moon in the solar system with an
atmosphere and is larger than the planet Mercury
A part of Saturn's
system of rings,
pictured by
Voyager 2 from a
distance of about
3 million km
(about 2 million
mi). More than
sixty bright and
dark ringlets are
seen here;
different colors
indicate different
surface
compositions.
Uranus and Neptune
 Uranus revolves around the Sun once about every 84 years.
 Both Uranus and Neptune have a core of rocky material surrounded
by water and ice.
 Uranus and Neptune have an atmosphere of hydrogen and helium
 Average temperature on Uranus is-210 OC (-350 OF)
 Average temperature on Neptune is –235 OC (-391 OF)
 Uranus tilts 82O on its axis, which is different from the less that 30O
for other planets.
 15 Known satellites around Uranus
 Uranus has 10 narrow rings and a number of dusty bands
 Neptune has 8 satellites
 Neptune also has a series of rings
Pluto
Not a planet but we won’t leave it
out!
 Recently changed to a dwarf planet
 Pluto’s atmosphere is probably mostly nitrogen, with some
methane and CO2
 Pluto orbits around the Sun once every 248 years
 Dwarf Planet:
 Orbits the sun, but is not massive enough to have cleared its own orbit
(meaning that there are other masses at the same distance form the
sun)
 Are smaller than planets (can be smaller than the moon)
This is a
photo image
of Neptune
taken by
Voyager.
Neptune has
a turbulent
atmosphere
over a very
cold surface
of frozen
hydrogen
and helium.
The interior structure of Uranus and Neptune.
Smaller bodies of the Solar
System
Comets
Small relative to other bodies in the solar
system
Made of frozen CO2, NH3, CH4 and
particles of dust and rock mixed in.
Originate approximately 30 A.U. from the
Sun
As a comet nears the
Sun it grows brighter,
with the tail always
pointing away from the
Sun.
Asteroids
 The asteroid belt lies between Mars and Jupiter
 The asteroids in this belt are between 1 km up to the largest
(Ceres) which is 1,000 km (600 mi)
 The asteroids in the inside of the belt are made of a stony
material and the asteroids on the outside of the belt are made of
a carbon material
 Some other asteroids are metallic, made of iron and nickel
Most of the asteroids in the asteroid belt are about
halfway between the Sun and Jupiter
Meteors and Meteorites
 Meteroids
 Remnants of asteroids and comets after the heat of the Sun and
collisions.
 Meteor
 The streak of light and smoke left in the sky by a meteoroid is called a
meteor.
 These are the shooting stars that we see in the sky
 Meteor shower
 Occurs when the Earth passes through a stream of particles that are
left by a comet.
 There is an intense meteor shower the third week in October as the
Earth crosses the path of Halley’s Comet.
Meteorite on Mars
Meteorite
 A meteorite is what is left of a meteoroid if it survives the
flight through the Earth’s atmosphere.
 Classified according to their makeup
 Iron meteorites
 made up mostly of iron and nickel material
 Stony meteorites
 composed mostly of rocky material much like that
found on Earth
 chondrites – have a structure of small spherical lumps
of silicate materials.
 Achondrites – do not contain this silicate clumps
 Stony-iron meteorites
 Made up of a conglomerate of both types of materials.
(A)A stony meteorite.
The smooth, black
surface was melted by
friction with the
atmosphere.
(B) An iron meteorite that
has been cut, polished, and
etched with acid. The
pattern indicates that the
original material cooled
from a molten material over
millions of years.