Download Solar System Formation

The Solar System - Its Origin
and Early Development
Sun and eddy
Solar System
The Solar System consists of the Sun and the other
celestial objects gravitationally bound to it: the eight
planets, three dwarf planets and their 165 known
moons.
 4 terrestrial planets or inner planets
 The Asteroid Belt
 4 gas giants or outer planets
 The Kuiper Belt
 The Oort Cloud
 Three dwarf planets scattered thru the solar
system
General Characteristics of the Solar System
• Planetary orbits and rotation
– Planet and satellite orbits are in a common plane
– Nearly all planet and satellite orbital and spin
motions are in the same direction
– Rotation axes of nearly all planets and satellites are
roughly perpendicular to the plane of the ecliptic
General Characteristics of the Solar System
• Chemical and physical properties of the planets
– The terrestrial planets are small, have a high
density, and are composed of rock and
metallic elements
– The Jovian planets are large, have a low
density, and are composed of gases and
frozen compounds
General Characteristics of the Solar System
• The three dwarf planets are Pluto, the
largest known Kuiper belt object; Ceres, the
largest object in the asteroid belt; and Eris,
which lies in the scattered disc.
Planetary Distances: In order of
their distances from the Sun
•
•
•
•
•
•
•
•
•
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto (dwarf planet)
0.4 AU
0.7 AU
1.0 AU
1.5 AU
5.0 AU
10.0 AU
19.0 AU
30.0 AU
39.0 AU
• Light travels through
space at 300,000-km/s.
• So it takes about 8
minutes for light from
the sun to travel 1 AU
and reach us.
• How long would it take
light from the sun to
reach Pluto?
• 39 x 8 = 312 minutes, or
5.2 hours!
Mass of the Solar System
• Almost all the mass in our
solar system is in the sun.
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•
•
•
•
Mass of the Solar System
Sun 99.80%
Jupiter 0.10%
Comets 0.05%
Other 7 planets 0.04%
– Total of Sun + Planets +
Comets = 99.99%
Planets
A planet is any body in orbit around the Sun
that
a) has enough mass to form itself into a
spherical shape and
b) has cleared its immediate neighborhood of
all smaller objects.
There are eight known planets that meets
this qualification: Mercury, Venus, Earth,
Mars, Jupiter, Saturn, Uranus and Neptune.
Dwarf Planets
• On August 24, 2006 the
International
Astronomical Union
defined the term "planet"
for the first time,
excluding Pluto and
reclassifying it under the
new category of dwarf
planet along with Eris
and Ceres.
Images of the Asteroid Ceres As It
Rotates One Quarter
Dwarf Planets
• A dwarf planet is not required to clear its
neighborhood of other celestial bodies. Other
objects that may become classified as dwarf
planets are Sedna, Orcus, and Quaoar.
Small Solar System Bodies
• Natural satellites, or moons, are those
objects in orbit around planets, dwarf
planets and SSSBs, rather than the Sun
itself.
The Solar System
• The eight bodies officially categorized as
planets are often further classified in several
ways:
• Chemical Composition
• Size
• Position Relative to the Sun
• Position Relative to the Earth
• By History
Chemical Composition
• Terrestrial or rocky planets: Mercury, Venus,
Earth, and Mars:
• The terrestrial planets are composed primarily of
rock and metal and have relatively high densities,
slow rotation, solid surfaces, no rings and few
satellites.
• Jovian or gas planets: Jupiter, Saturn, Uranus, and
Neptune:
• The gas planets are composed primarily of
hydrogen and helium and generally have low
densities, rapid rotation, deep atmospheres, rings
and lots of satellites.
Size
• Small planets: Mercury, Venus, Earth, Mars.
The small planets have diameters less than 13000
km.
• Giant planets: Jupiter, Saturn, Uranus and
Neptune.
The giant planets have diameters greater than 48000
km.
The giant planets are sometimes also referred to as
gas giants.
Relative the the Sun
• Inner planets: Mercury, Venus, Earth and
Mars.
• Outer planets: Jupiter, Saturn, Uranus,
Neptune.
• The asteroid belt between Mars and Jupiter
forms the boundary between the inner solar
system and the outer solar system.
Relative the the Earth
• Inferior planets: Mercury and Venus.
• closer to the Sun than Earth.
• The inferior planets show phases like the Moon's
when viewed from Earth.
Earth.
• superior planets: Mars thru Neptune.
• farther from the Sun than Earth.
• The superior planets always appear full or nearly
so.
History
• Classical planets: Mercury, Venus, Mars, Jupiter,
and Saturn. Known since prehistorical times. Visible
to the unaided eye
• Modern planets: Uranus, Neptune. Discovered in
modern times. Visible only with optical aid
(telescopes)
• The IAU has recently decided that "classical" should
refer to all eight planets (Mercury thru Neptune,
including Earth but not Pluto). This is contrary to
historical usage but makes some sense from a 21st
century perspective.
Origin of the Solar System
• The Solar System is believed to have
formed according to the nebular hypothesis,
first proposed in 1755 by Immanuel Kant
and independently formulated by PierreSimon Laplace.
Origin of the Solar System
• This theory holds that 4.6 billion years ago
the Solar System formed from the
gravitational collapse of a giant molecular
cloud. This initial cloud was likely several
light-years across and probably birthed
several stars.
Origin of the Solar System
• About 4.5 billion years ago it is believed that the
Solar System consisted of a large cloud of gas and
dust, called a nebula.
• This cloud started rotating, and the dust particles
combined to form planetesimals. As the cloud
rotated faster, it flattened, and the planetesimals
formed.
• The Sun is at the center, and secondly, the planets in
orbit around the Sun. This model explains
qualitatively many features of the Solar System,
including the fact that the planets essentially all
revolve around the Sun in the same plane.
Nebular Hypothesis of Solar System Formation.
The Solar System – the Relative Sizes of the Planets
The Terrestrial Planets
• Terrestrial planets seem to have experienced a
similar early history, with extensive volcanism,
cratering, and internal differentiation
• Each has a metallic core and a silicate mantle
crust, and shows evidence of continuing lava
flows and meteorite impact
• Outgassing produced an atmosphere as light
gases from the interior rose to the surface
during volcanism
MERCURY
Mercury, the planet nearest the Sun, is the
second smallest planet in our solar system.
It is only slightly larger than the Earth's
moon. The surface is covered with craters.
This tiny planet does not have any rings or
moons.
Evidence of
craters
MERCURY
•
•
•
•
Diameter: one third the size of Earth
Distance: 0.4 AU
Atmosphere: no atmosphere
Features: Craters with smooth plains and
most extreme temperature range
• No life because of atmosphere
• No moons or satellites
Mercury
• Closest to the sun.
• Temperature ranges
from 427°C in
daylight to -173°C at
night.
• Revolves slowly, in
two Mercury years
three Mercury days
will have passed.
• One third the size of
the Earth.
•Period of Rotation = 88 days
•Period of Revolution = 59 days
Mercury Missions
• Environment,
Geochemistry,
and Ranging
(MESSENGER)
is the first
mission sent to
orbit the planet
closest to the sun.
•On Oct. 6, 2008, the probe flew by Mercury for the second
time this year, using the planet’s gravity for a critical assist
needed to keep the spacecraft on track for its orbit insertion
around the planet three years from now.
VENUS
lava flows
impact craters
Venus is one of the brightest
objects in our sky, so it is clearly
visible to the naked eye. It can
be tricky to spot because it is
always near the Sun.
It rises and sets with the Sun
each day.
Ancient civilizations believed
Venus was actually two different
objects, so they called the one
that rose the Morning Star, and
the one that set the Evening
Star.
VENUS
•Period of Rotation = 108.2 days
•Period of Revolution = 243 days
• Almost same size as the Earth.
• Hottest surface in our solar
system. The average daytime
surface temperature is 464°C,
compared to the Earth’s 15°C.
• This is hot enough to melt lead.
• Named for the Roman goddess
of love and beauty. Originally
the Greek goddess Aphrodite.
VENUS Missions
Venus Express is ESA’s first
mission to Venus. Launched in
November 2005, the spacecraft
arrived at the planet on 11 April
2006 and began science
observations within a month.
Since then, it has continuously
been making new discoveries
and revising our knowledge of
Venus.
• Venus is covered by a thick
layer of clouds that extends
between 45 and 70 km above
the surface. These rapidlymoving clouds are mainly
composed of micron-sized
droplets of sulphuric acid and
other aerosols (fine solid or
liquid droplets suspended in a
gas), the origin of which is
unknown.
EARTH and MOON
What similarities and
differences do you notice
between the Earth and the
Moon?
Why do they have such
different surface features?
MARS
Mars is very bright, which makes it easy to spot in the night sky. It was named after
the Roman god of war because its reddish color reminded the people of blood.
Olympus Mons
is the largest
volcano in our
solar system!
Although people have
never landed on Mars,
we have sent robotic
explorers there.
Martian crater
Mars
• Mars is the Latin name for
Ares, the Greek god of war.
•Mars has an atmosphere that is mainly carbon dioxide.
•It is very thin, only 0.01 atmosphere’s at the surface.
•Mars even has clouds, but they are thin also.
•The winds can create dust storms that cover much of the
planet and last for months.
A surprising find made
by Mariner 9 was the
existence of several
canyons that are much
larger than Earth’s
Grand Canyon. The
largest, Valles
Marineris, is thought to
have formed by
slippage of material
along huge faults in the
crustal layer. In this
respect, it would be
comparable to the rift
valleys of Africa.
Mars
• Mars has two very
small moons, Phobos
and Diemos.
• They are named after
the horses that pulled
Mars’s chariot.
• The larger Deimos is
only 23-km in
diameter.
•Mars is about half the size of the Earth.
•A 100 pound sixth grader would weigh 39 pounds on Mars.
•It is very cold on Mars, with the average temperature ranging
from -140° C to 20° C.
•Period of Rotation = 108.2 days
•Period of Revolution = 243 days
Mars
• Mars surface has a
wide variety of
landscapes.
• Olympus Mons is the
largest volcano in our
solar system. Its base
would cover the state
of Colorado.
• It is three times taller
than Mt. Everest.
• There are many other
volcanoes on Mars, but
none seem to be active
at this time.
Mars Missions
• There have been many missions to
Mars, starting with the Viking
craft in 1976.
• There are currently two orbiters
and two rovers collecting data on
Mars.
• Manned missions are also
currently being planned, around
2025 or so.
Mars Missions
• Next NASA Mars Mission
Rescheduled For 2011
NASA's Mars Science
Laboratory will launch two
years later than previously
planned, in the fall of 2011.
The mission will send a
next-generation rover with
unprecedented research
tools to study the early
environmental history of
Mars.
The composition and markings of some
Martian rocks indicate that liquid water
was once present on Mars’s surface. The
marking shown in the center of the rock,
however, was created by a NASA rover
during chemical analysis.
ASTEROID BELT
Most asteroids can be found in the Asteroid Belt, which is located between
Mars and Jupiter. Asteroids are rocky and metallic objects that orbit the Sun,
but are too small to be considered planets. They are known as minor planets.
Asteroids range in size from Ceres, which has a diameter of about 1000 km,
down to the size of pebbles.
The main
asteroid belt
occupies the
orbit between
Mars and
Jupiter,
between 2.3
and 3.3 AU
from the Sun.
Asteroid Belt: Ceres
• Ceres (2.77 AU) is the largest body in the
asteroid belt and its only dwarf planet. It has a
diameter of slightly under 1000 km, large
enough for its own gravity to pull it into a
spherical shape. Ceres was considered a planet
when it was discovered in the 19th century, but
was reclassified as an asteroid in the 1850s as
further observation revealed additional
asteroids. It was again reclassified in 2006 as a
dwarf planet.
Gas Giants
• Separated from the 1st
zone by the asteroid
belt, the 2nd Zone
contains the gas giants.
• Made of the lightweight
elements Hydrogen,
Helium, Carbon,
Oxygen, and Nitrogen.
•All are much larger than the Earth, with 15-300 times the mass,
and 4-11 times the diameter.
•Not believed to have solid surfaces.
•Have rings and many satellites.
JUPITER
Jupiter, the fifth planet from the Sun, is the largest planet in our solar system.
Jupiter is so big that over 1,000 planets the size of Earth could fit into it.
It has over 60 moons and 2 rings. Can life exist on Jupiter's moon, Europa?
The “Great Red Spot”
Is actually a huge
Storm system!
Here are a few of Jupiter’s moons
Jupiter
• Named for Jove, the
King of the Roman
Gods.
• Roman name for the
Greek god Zeus.
• Often the term Jovian
is used to describe
things pertaining to
Jupiter. Example: the
Jovian moons.
Jupiter
• Believed to be a failed
star, lacking the mass
to become a small star.
• Most massive planet in
solar system.
• Has over 60 satellites.
• Density is 1.33g/cm3.
• Rotates every 10 hours.
• Takes 12 years to orbit
the sun.
• Gravity almost 2.5
times that of the Earth.
Jupiter
• The red spot is a huge
storm that has been
continuously going
on Jupiter for over
400 years. Winds
inside this storm
reach speeds of about
270 mph. With a
diameter of 15,400
miles, this storm is
almost twice the size
of the entire Earth.
Period of Rotation = 778.3 days
Period of Revolution = 11.86 years
Moons of Jupiter
• The New Horizons Long
Range Reconnaissance
Imager (LORRI) captured
these two images of
Jupiter's outermost large
moon, Callisto, as the
spacecraft flew past Jupiter
in late February. New
Horizons' closest approach
distance to Jupiter was 2.3
million kilometers (1.4
million miles), not far
outside Callisto's orbit,
which has a radius of 1.9
million kilometers (1.2
million miles).
•However, Callisto happened to be on the
opposite side of Jupiter during the spacecraft's
pass through the Jupiter system, so these
images, taken from 4.7 million kilometers (3.0
million miles) and 4.2 million kilometers (2.6
million miles) away, are the closest of Callisto
that New Horizons obtained.
SATURN
Saturn, the sixth planet from the Sun, is the second largest planet in our solar system.
It is often called the ringed planet because many rings of dust and rocks surround it.
Saturn also has over 31 moons.
Saturn with some of
its moons
Some of Saturn’s rings
Titan is a moon of Saturn that may have some
Conditions necessary for life! The picture on
the right shows an artist’s drawing of how Titan
might have looked when the Cassini-Huygen’s
probe dropped into its atmosphere in Dec., 2004.
Saturn
• Saturn was the Roman God of
the Harvest and of Time.
• Father of Jupiter, Neptune, and
Pluto.
• The Roman name for the
Greek god Cronos.
• Saturnalia was the mid-winter
festival in Saturns honor. It
lasted seven days, and there
was much merrymaking.
Public business was suspended
and schools were closed.
Parents gave presents to their
children.
• 2nd largest planet in
solar system.
• A “day” on Saturn is a
little over 10 hours
long!
• It takes 29 years to
orbit the sun.
• Almost 10 times larger
than Earth.
• Most visible rings of
any planet.
• Density is 0.69 g/cm3.
• If a large enough ocean
could be found, Saturn
would float in it!
Saturn
Period of Rotation = 1,427 days
Period of Revolution = 29.46 years
URANUS
Uranus is a very unusual planet because it sits on its side with north and south
poles sticking out the sides. It rotates around this axis, making it look like a ball
rolling around in a circle around the Sun.
some of Uranus’s moons
Black rings
Uranus
• URANUS: Great
primeval God of
the Sky. Born of
GAIA, the Earth,
he covered the
world in the form
of a vast bronze
dome and ruled
over everything.
Uranus
• Diameter is like 4 Earth’s.
• Mass is 14.5 Earth’s.
• Takes 84 years to revolve
around the sun.
• Day is a little over 17
hours long.
• Has more than 20 moons.
Uranus Axis
• Uranus is considered
unusual because the
planet is tipped on its
side. The poles actually
point towards the Sun.
This is due to the fact
that its magnetic field is
tilted 60 degrees from
the axis of rotation.
• It is believed that
Uranus was struck by a
large object that
knocked Uranus on its
side.
NEPTUNE
Neptune, usually the eighth planet from the Sun, is a very cold place.
Occasionally, Pluto crosses Neptune’s orbit and becomes the eight planet.
Its bluish color comes from its atmosphere of methane gas.
Tiny Dark Moon
Neptune
• Neptune is the Roman
god of the sea.
• The Romans modeled
him after the Greek god
Poseidon.
Neptune
• Neptune revolves on
its axis every 18 hours.
• It takes 165 years to
revolve around the sun
once.
• Has the mass of 17
Earths.
• Has 13 moons.
•Diameter is almost 4 times larger than Earths.
•Blue-green color is from the methane in the atmosphere.
•At times it is the furthest planet from the sun.
Neptune
• Diameter: 4 times the size of Earth
• Distance: 30 Au
• Atmosphere: 80% Hydrogen 19% Helium 1.5%
Methane
• Features: At times it is the furthest planet from the
sun. Icy clouds and enormous storms
• Life:possible life on one of its moons called Triton
PLUTO
Pluto, usually the ninth planet from the Sun, is the smallest planet in our solar system.
Some scientists believe that Pluto once was one of Neptune’s moons, and that it
pulled out away from Neptune and made its own orbit.
Clearest view to date
Of Pluto and Charon
Pluto
• Usually the furthest planet
from the sun.
• 2/3rds the size of our moon.
• Has one moon, Charon.
• So cold that oxygen and
nitrogen in its atmosphere is
frozen solid.
• Only planet not visited by a
spacecraft.
• Pluto takes 248 years to
make one orbit around the
sun!
Pluto
• When Pluto comes close
enough to the sun, the
surface of solid Nitrogen
sublimates to produce a
substantial atmosphere with
winds and clouds.
• Because the planet is so
small, however, it does not
have enough gravity to bind
an atmosphere for very
long. Thus Pluto's
atmosphere is being rapidly
produced and rapidly lost at
the same time.
•This means that the
atmosphere is not in
equilibrium.
• Pluto
(39 AU
average), a
dwarf planet,
is the largest
known
object in the
Kuiper belt.
Pluto
•When discovered in 1930 it was
considered to be the ninth planet; this
changed in 2006 with the adoption of a
formal definition of planet.
New Horizons Pluto Kuiper Belt Flyby
The mission is expected to arrive
at Pluto sometime in 2015.
•Pluto has a
relatively eccentric
orbit inclined 17
degrees to the
ecliptic plane and
ranging from
29.7 AU from the
Sun at perihelion
(within the orbit of
Neptune) to
49.5 AU at
aphelion.
COMETS
Comets are sometimes called dirty snowballs or "icy mudballs".
They are a mixture of ices (both water and frozen gases) and dust that for
some reason didn't get incorporated into planets when the solar system was formed.
This makes them very interesting as samples of the early history of the solar system.
Comets have
elliptical orbits.
Comet Halley in 1910
When we see a comet, we
are seeing the tail of the comet
as comes close to the Sun.
Kuiper belt
• The Kuiper belt, the
region's first formation, is a
great ring of debris similar
to the asteroid belt, but
composed mainly of ice. It
extends between 30 and
50 AU from the Sun. This
region is thought to be the
source of short-period
comets, such as Halley's
Comet.
•It is composed
mainly of small solar
system bodies, but
many of the largest
Kuiper belt objects,
such as Quaoar,
Varuna, and Orcus,
may be reclassified as
dwarf planets.