Transcript The Solar System

The Solar System
Chapter 2
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The Solar System Evolves
• Solar system began about 5 billion years ago
– Changing ever since
– Began as a cloud of dust and gases
– Very cold
• Solar system consists of the following:
– Sun
– Planets
– Other objects that revolve round the sun
• Nebular Theory – the solar system began as a
huge cloud of dust and gas called a nebula, which
later condensed to form the sun and its 9 planets
The Sun forms First
• Nebula, which solar system formed, primarily of
Hydrogen and Helium
• Planets contain a wide variety of gases
• Star exploded in a supernova
– Sending heavy metals into space
– Seeded themselves into nebula
– Nebula began to collapses, causing it to spin faster,
flattening out with a protosun forming in the middle
– As nebula continued to collapse protosun grew larger
– Over millions of years gravitational forces caused
Hydrogen atoms to fuse and form Helium
– Gave off great heat and light causing a star to be born
– The Sun
The Planets Form
• Gases continued to spin around the sun
• Gravity caused for some gases to clump
together, growing larger over time
• Protoplanets – early stages of planets
– Those near sun got so hot that lightweight gases,
Hydrogen & Helium boiled away
– Collections of rocky material and metals
– Mercury, Venus, Earth, Mars
• Protoplanets farther from sun maintained gases
and grew to enormous sizes
• Jupiter, Saturn, Uranus, Neptune
• As planets cooled over time smaller clumps
formed around them becoming satellites and
moons
• Astronomers believed a satellites broke away
from Neptune and became known as Pluto
• Small clumps exist known as Asteroids (rocklike
objects)
– Asteroid Belt found between Mars & Jupiter
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Motions of the Planets
• Planets got name from the Greeks meaning
“wanderers”
Earth at the Center?
• Ptolemy – Greek scientist, proposed that the
Earth was at the center of universe
– All objects travelled in orbits around Earth, which
didn’t move
– Orbit – path 1 object takes when moving around
another object in space
– Orbits were perfect circles
– Universe was unchangeable
– Ptolemy’s theory held to be true for over 1400
years
Sun at the Center?
• Nicolaus Copernicus – Polish astronomer
developed a theory that the Earth and other
objects revolved around the sun
• All planets revolve around sun in same
direction
• Each planet took different amt of time to
revolve around sun
• Also believed orbits were perfect circles
Elliptical Orbits
• Johannes Kepler – German mathematician
and astronomer, supported Copernicus’
theory
– Found that paths of planets were not perfect
circles but elliptical in shape (oval or egg-shaped)
– Kepler was correct
– Planets travel in a counterclockwise elliptical orbit
around the sun
– Planets closest to the sun travel the shortest
distance taking less time to orbit
Inertia and Gravity
• Sir Isaac Newton – English scientist explained why the
planets stayed in motion instead of shooting off into
space
– Law of Inertia – a moving object will not change speed or
direction unless an outside force causes a change in its
motion
– Sun’s gravitational pull was the force acting on the planets
• Inertia and Gravity are 2 factors that keep planets in
motion around the sun
– Inertia causes planets to move in straight line
– Gravity pulls planets toward sun
– Combined cause an elliptical motion
Period of Revolution
• Period of Revolution – time it takes planet to
make 1 revolution around the sun
– Period of revolution is it’s year
– The closer the planet is to the sun the shorter it’s
year
– Mercury’s year = 88 days
– Earth’s year = 365 days
– Pluto’s year = 90,520 days
Period of Rotation
• All planets spin/rotate on it’s axis
– Axis – imaginary line that runs through the center
of a planet
– Period of Rotation – time it takes planet to rotate
1 time on it’s axis
– Earth’s rotation = 24 hours or 1 day
– Mercury’s rotation = 59 Earth-days (1416 hours)
– Pluto’s rotation = 6 Earth-days (144 hours)
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A Trip Through the Solar System
• There are 9 planets in our Solar System
– Each has unique surface and atmosphere
– See page 68-69
Mercury – Faster that a Speeding
Bullet
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Closest planet to the sun
Little to no atmosphere, no weather
No change to surface from billions of years prior
Revolves around the sun in 88 days at 48 km/sec
Named after the speedy messenger Roman god
1975 United States sent Mariner 10 to explore
– Crater-covered world
– Craters scooped out about 10 billion years ago from
pieces of material striking the planet
– Long steep cliffs, some hundreds of km across
• Mercury rotates on its axis very slow
– 59 Earth days for 1 rotation
– Rotates 3 times abt its axis for every 2 revolutions
around the sun
– Produces a sun rise every 175 Earth days
– Temperatures range from 427°C during the day
and -170°C at night
Venus – Greenhouse in the Sky
• Named after Roman goddess of beauty & love
• Abt same diameter, density, and mass as Earth
– Once called Earth’s twin
• Thick cloud cover
(more that 5 times as
dense as Earth’s clouds)
• US spacecraft Pioneer Venus Orbiter and
Magellan were placed in orbit and were able
to map the surface
– Winds more than 350 km/hr
– Clouds made of droplets of sulfuric acid and
carbon dioxide
– Volatile atmosphere, lightning and acid rain
– Rapid increase in temperature and pressure
(hotter than Mercury)
– Pressure is 91 times that on earth
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Deep canyons, craters, & vast plains
Remains of once active volcanoes
Clouds hide surface from sun
Sun slowly rises in west and sets in east b/c Venus
rotates east to west
– Retrograde rotation – reverse motion
– Rotates 1 time on it’s axis every 243 Earth-days
– Takes 224 Earth-days to revolve 1 time around sun
• Day is longer than its year
• Scientists believe billions of years ago Venus was
covered in vast oceans
– Coastlines and dried up sea beds detected
– As water evaporated as sun grew hotter as it got older,
water vapor became trapped creating a Greenhouse Effect
Mars – The Rusty Planet
• 4th planet from the sun
• Named after the Roman god of war due to its reddish
color (blood)
• 2 moons circle Mars: Phobos & Deimos
• Surface rocky and heavily cratered
• Viking 1 & Viking 2
(US spacecrafts)
– Landed on Mars
– Analyzed Martian soil
• Soil is similar to Earth’s
• Contains a lot of Iron oxide
giving it the reddish color
• Has a very active past such as huge volcanoes
– Olympus Mons – largest volcano on Mars & Solar
System
• Wider than Hawaii and 3 times as tall as Mt Everest
– When volcanoes were active they poured out lava
and steam (steam cooled and fell as rain)
– Rushing rivers gouged out channels across Mars
– No liquid water found
– Frozen water found in Northern Icecaps (never
melts)
– Southern Icecaps made of frozen carbon dioxide
– Melt in summer (only 0°C in summer due to thin
atmosphere
The Asteroid Belt
• Thousands of rocks and “flying mountains”
known as “minor planets”
– Sweep around sun btwn orbits of Mars and Jupiter
Jupiter – Planet that was almost a Star
• Named after the Romans king of the Gods
• Made primarily of Hydrogen & Helium gases
– Similar to the sun
• Temperature: 30,000°C in the core
– Scientist believe if Jupiter had gotten any larger in the
formation of the solar system that it may have
undergone nuclear fusion and became a star
• Can only see Jupiter’s atmosphere from Earth
– Appear as bands of color made of hydrogen & helium
• Huge storms swirl the atmosphere of Jupiter
• Giant Red Spot – 3 times the size of Earth, is a
hurricane-like storm in Jupiter’s atmosphere
– Over 20,000 years old
• Huge atmospheric pressure due to thick cloud
cover
• Surface covered by huge Hydrogen oceans
– Due to high pressure the liquid Hydrogen acts like a
metal that surrounds the core
– This layer causes Jupiter’s gigantic magnetic field
called the Magnetosphere
– Stretches millions of km beyond the planet
– Largest single structure in the solar system
• Jupiter gives off more heat than it receives from
the sun
• Voyager 1 & 2 flew past Jupiter in exploration
– Discovered a thin ring around it
– Enormous lightning bolts in atmosphere
– Mysterious shimmering sheets of light in sky
• Galileo observed 4 moons orbiting Jupiter
– Known as the Galilean satellites
– Today more that 16 moons have been discovered
• Io – innermost and large moon of Jupiter
– Rich in colors of red, yellow, and orange
– has a very young surface due to the active volcanoes
constantly covering the surface with new material
• Europa – ice-covered, smaller that Io
– Smooth, bright white surface
– Photos show a volcano that appears to spew out
water and ammonia ice
• Ganymede – largest moon in solar system
– Half ice, half rock
– Mostly craters
• Callisto – most heavily
cratered moon in
solar system
– Took billions of years to
create all the craters
– Very little activity
Saturn – A World of Many Rings
• Surrounded by beautiful rings
– Made of icy particles
– Range in size from .001 mm – 100 km diameter
– Farthest ring is 30,000km from planet
• Spins very fast on its axis
– So fast it flattens at its poles
• Made of Hydrogen and
Helium gases
• Many violent storms
and huge lightning storms
• Clouds form bands around planet
– Bands alternate in color giving off a reddishorange color in its southern hemisphere
• Giving off a similar look as Jupiter’s Giant Red Spot
– Gives off more heat that it receives from sun
– Huge magnetic field
– Least dense planet in solar system
• Saturn has more moons than any other planet
– Titan is its largest moon & surrounded by many
deadly gases (hydrogen cyanide, methane, etc)
Uranus – A Planet on its Side
• Named for the father of Saturn in Roman mythology
• Twice as far from sun as Saturn
• Gas giant like Jupiter and Saturn
– Covered by thick atmosphere of Hydrogen, Helium, & Methane
• Greenish in color
• Very cold at top of clouds (-220°C)
• Uranus’ axis is tilted at a 90° angle
– Appears to be tipped on its side
• 9 rings made of methane ice
surround planet
• 15 moons that vary in size
Neptune – The Mathematician’s Planet
• Roman god of the seas
– Named for its bluish color
• Altered the orbit of Uranus due to
gravitational forces
• Neptune & Uranus known as “Twin Giants”
– Similar in size, mass, & temperature
• Covered by thick clouds of Methane float in a
Hydrogen & Helium atmosphere
• Voyager 2 discovered Neptune has 5 rings
– Made of dust particles formed from meteorites
that crashed into Neptune’s moons
• 8 moons
– Triton – 4th largest moon in solar system
• Covered in frozen Methane
• Orbits Neptune backward/retrograde
Pluto – A Double Planet
• Discovered in 1930 by Clyde Tombaugh
• Named for Roman god of the Underworld
• Smallest and least massive planet in solar
system
• Been removed from solar
system as a planet
Comets
• Oort Cloud – vast collection of ice, gas, & dust
– 15 trillion km from sun
– Gravitational pull of a star will pull a “dirty snowball” out
and send it speeding toward the sun
– Mountain sized object known as a Comet
• Nucleus – core of comet
• Coma – cloud of gas & dust surrounding nucleus
• Nucleus and Coma make up the Head of comet
– Gets hotter and larger the closer it gets to sun
• Solar winds blow coma outward into a long tail
– Streams away from sun
– Tail of incoming comet streams out behind it
– Tail of outgoing comet streams in front of it
• Long period comets orbit the sun over & over
again
– Long, elliptical orbits, reaching the edge of solar
system
– Take thousands of years to make 1 orbit
• Short period comets return every few years
– Halley’s Comet most famous
– Returns every 75-79 yrs
Meteoroids, Meteors, and Meteorites
• Meteoroids – chunks of metal or stone that
orbit the sun
– Come from Asteroid Belt or comets
• Meteor – streak of light produces by a burning
meteoroid
– Known as “Shooting Stars”
– Most burn up in the atmosphere
• Meteorite – meteor that survives the
atmosphere and strikes the Earth
– Composed mainly of Iron, Nickel, and Stone