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Solar System
Reese
Measuring distance in space
• Astronomers use astronomical units to measure distance
in space because distances in space are VERY BIG.
• 1 AU = 150,000,000 kilometers away (Distance between
Earth and Sun)
• If distances are even farther, then astronomers use lightyears. A light-year is the distance light travels in one year.
• Light travels at 300,000 km/sec
• 1 light-year = 10 trillion km
• The next closest star (Alpha Centauri) is 4.3 light-years
away!
Measuring distance in space
• Milky Way is 100,000 light-years across and
has 100 billion stars.
• The next galaxy is 60,000 light-years away.
How did it all begin?
Big bang proponents suggest that some 10 billion to 20 billion
years ago, a massive blast allowed all the universe's known matter
and energy to begin to expand.
Our solar system which is located in one of the spiral arms of the
Milky Way galaxy, began about 4.6 billion years ago when a cloud
of dust, hydrogen gas, helium, and other elements drifted in our
galaxy and began to condense.
As more and more cloud began to clump together, the intense
pressure and weight of the gases resulted in nuclear fusion and our
sun formed first in the center.
Once ignited, the Sun's powerful solar winds began to blow. These
winds, which are made up of atomic particles being blown outward
away from the Sun, slowly pushed the remaining gas and dust out
of the Solar System.
Big Bang Continued…
With no more gas or dust, the planets, minor planets, moons,
comets, and asteroids stopped growing.
The inner planets which are much closer to the Sun, were
impacted more by the solar winds and it gave them less time
to grow.
The outer planets grew larger and their gravity had time to
accumulate massive amounts of gas, water, as well as dust.
What is a Solar System?
• Our solar system is a group of interacting
celestial bodies(planets, moons, asteroids,
comets, meteoroids, minor planets) that orbit
around the Sun due to its gravitational pull on
them.
What is a galaxy?
• A galaxy is a group of millions or billions of
stars, gas, and dust, held together in space by
the force of gravity. Our solar system belongs
to the Milky Way galaxy. The Milky Way
galaxy is a barred spiral-shaped galaxy.
Geocentric vs Heliocentric
• Geocentric = Earth is at the center of the
revolving planets and stars.
– Greeks (Ptolemy)
• Heliocentric = Earth and other planets revolve
around the sun.
– Copernicus, Galileo, Kepler
Geocentric Theory Scientist
Copernicus
• Nicolò Copernico; (19 February 1473 – 24 May
1543) was a Renaissance astronomer and the
first person to formulate a comprehensive
heliocentric cosmology, which displaced the
Earth from the center of the universe.
Kepler
• Johannes Kepler (December 27, 1571 –
November 15, 1630) was a German
mathematician, astronomer, and astrologer,
and key figure in the 17th century scientific
revolution. He is best known for identifying
the motion of the planets around the sun as
an ellipse.
Galileo
• Galileo Galilei 15 February 1564– 8 January
1642)was an Italian physicist, mathematician,
astronomer and philosopher who played a
major role in the Scientific Revolution. His
achievements include improvements to the
telescope and consequent astronomical
observations, and support for Copernicanism.
He is known as "the Father of Modern
Science."
SUN
• Our sun is a star at the center of our solar
system. Our sun supports life on Earth, affects
seasons, climate, weather, and currents in the
ocean.
• Our sun is a medium size star (yellow main
sequence star).
SUN
• The sun is basically a ball of gas (plasma). The
main gases that it consists of are hydrogen
and helium but it has other trace elements.
Why is the sun’s gravity so strong?
• The sun’s gravity is the strongest force in our solar
system. It is strong enough to hold ALL of the
planets and comets in orbit. The reason the sun has
such a high gravity is due to its immense mass.
• The sun contains 99.86 percent of the mass of the
solar system! The sun is 330,000 times the mass of
Earth.
Example: If you weigh 80 lbs on Earth, you would
weigh 2,244 pounds on the surface of the sun.
What are some sun statistics?
• 1,384,000 km in diameter
• 149.6 million km away from Earth
• It takes 25 Earth days for it to rotate on its axis
Where does the sun’s energy come
from?
• The sun gets its energy from nuclear fusion..
• Nuclear fusion occurs when hydrogen atoms bond
together to form helium. This bonding is the source
of energy for the sun.
• Nuclear fusion can only be achieved when
temperatures are EXTREMELY HIGH (15 million
degrees Celsius) and EXTREMELY HIGH pressure
exists.
• The sun is currently about 5 billion years old and it
has enough energy to last another 5 billion years.
Nuclear Fusion
SUN Layers
Sun’s 4 main layers
• CORONA: the outermost atmosphere layer
(stands for crown in latin). The corona’s job is
to eject out a stream of electrically charged
particles called solar wind. You can only see
this layer during a total eclipse of the sun.
• CHROMOSPHERE: (inner atmosphere). The
chromospheres' job is to create the reddish
color for the sun.
Sun’s 4 main layers
• PHOTOSPHERE: visible surface layer. The
photosphere’s job is to produce light. The visible
light we see on Earth comes from this layer. Even
though this layer is very hot, it is cooler than the
core and therefore sunspots sometimes appear
on this layer.
• CORE: innermost layer. Nuclear fusion occurs at
the core. The only place in the sun that is hot
enough and has enough pressure for the process
to happen.
Sun’s unique features
• Sunspots: areas of gas on the sun found of the
photosphere that are cooler than the gases around
them (we see as dark spots). Sunspots are magnetic
storms with magnetic fields that occur in pairs. They
can last for days or weeks before they disappear.
Sunspots have an 11 year cycle.
Magnetic Field Protection
Sun’s Unique Features
• Prominences: reddish loops of gas that
connect different parts of sunspot regions.
Prominences occur in the chromosphere.
Solar Flare
• Solar Flares: explosions of hydrogen gas that
release large amounts of energy . Solar flares can
lead to increases in solar wind (from corona) which
can reach the Earth’s atmosphere and disrupt the
magnetosphere. Disruptions in the magnetosphere
can lead to electrical, satellite, radio, and telephone
problems on Earth. Solar flares occur in the
chromosphere.
What is a solar eclipse?
• A solar eclipse is when the Sun is fully or
partially covered due to the moon (new moon)
passing between the Sun and Earth in just the
right alignment.
Gravity
• Gravity is the force that causes two particles to
pull towards each other. For objects on Earth, the
pull is towards the center of the Earth.
• The amount of gravity one object exerts on
another depends on the mass and distance
between the two objects. The more mass an
object has (like the Sun) the stronger its gravity.
The more distance between two objects, the
weaker the gravitational pull between them.
Mass
• The amount of matter (particles) that an
object is made of. Mass never changes even if
gravity changes.
Weight
• Weight is the mass of an object plus the force
of gravity pulling down on the object.
• Weight DOES change when gravity changes. If
you are on a planet with less gravity, you
“weigh” less. If you are on a planet with more
gravity, then you “weigh” more.
Inertia
• An object in motion will stay in motion unless
a force acts on it. An object at rest will stay at
rest unless a force acts on it.
Why planets orbit the sun
What is a planet?
• A planet is defined as a large spherical body
that revolves around the sun in the solar
system.
How do the planets differ?
• Planets differ in size, composition, mass, force
of gravity, distance from the sun, temperature,
and number of natural satellites.
What do all planets have in common?
• All our planet’s reflect light. They all revolve
and stay in orbit because of gravity. They all
have inertia. The amount of gravity a planet as
is directly related to the mass of the planet.
More massive planets have larger gravitational
pulls. All planets have a core. All planets rotate
on their axis.
How many planets are in our solar
system?
• Scientist currently agree that there 8 planets
and 1 dwarf planet. They are categorized into
the inner and outer planets based on their
characteristics.
• The first four are called the inner planets. They
are small and rocky.
• The following four are very large in comparison
to the first four and are gaseous.
Planet Images (NOT TO SCALE)
INNER
PLANETS
MERCURY
JUPITER
VENUS
SATURN
EARTH
URANUS
OUTER PLANETS
MARS
NEPTUNE
What are satellites?
• A satellite is any natural or artificial object that revolves around
an object in space. Our satellites revolve around Earth. Man
made satellites are used to photograph and relay information
for weather systems, support our telephone and media
communications, measure our atmosphere, spy and provide
GPS location.
• A space station is a satellite that people can live in for long
periods of time.
What is a moon?
• A moon is a natural satellite of a planet. A satellite is
an object that stays in orbit around the planet.
• The Earth has one moon. The moon’s surface is thick
with dust and has many rocks of various sizes.
• The moon is lit by sunlight bouncing off of it
(reflecting). The shape appears to change (moon’s
phases) as it revolves around the Earth every 27.3
days.
Moon
• Notable features of the moon are its plains (made
out of volcanic rock), its lunar mountains, and
craters.
• The moon has no water and no atmosphere (no
air). Temperatures range from -172 degrees
Celsius to 114 degrees Celsius.
• The mass of the moon is 1/6 that of Earth
therefore it has a lower gravitational pull.
• Moon is 384,400 km away from Earth and is
3,476 km in diameter.
Moon’s Features
Moon causes tides on Earth
• The moon causes the tides on Earth. The tides
occur due to the pull of the moon’s gravity.
What is a lunar eclipse?
• An eclipse of the Moon is caused by Earth
passing between the Sun and the Moon aligned
in a specific way.
Comet
• Comets: a mixture of frozen gases and tiny dust particles
that are sometimes called “dirty snowballs.”
• Nucleus = solid portion of a comet (inner layer).
• Coma = halo of dust and gas that forms around the nucleus
of a comet.
Comets have “tails” that may extend millions of km into
space! They face away from the sun.
• Like other objects in space, comets orbit the sun. Comets
have an elliptical shaped orbit.
• Most comets exist in the Oort Cloud > 50 AU away(long
period) and Kuiper Belt (30 AU away)(short period).
• A famous comet know as Halley’s comet was last seen in
1986. It revolves around the sun every 76 years.
Comet
Kuiper Belt
What are ASTEROIDS?
• Asteroids: they are the next largest objects in
our solar system after the (sun, moons, and
planets) and look like lumpy potatoes. Asteroids
are large rocks that are sometimes called “minor
planets.” Some think that asteroids are
remnants of a planet that never formed. Most
asteroids revolve around the sun between the
orbits of Mars and Jupiter. This is known as the
asteroid belt.
Have asteroids stuck Earth?
 Many astronomers and biologists think a big comet
or asteroid caused the dinosaurs to go extinct 65
million years ago, when a 10- to 15-kilometer wide
uncontrolled flying object whacked the Caribbean
Sea, forming a crater about 180 kilometers in
diameter near the Yucatan Peninsula.
 The heat of impact with the atmosphere and
surface caused a firestorm over much of North
America. Then vast clouds of dust and smoke
shaded the planet, causing a cold spell that
terminated the million-century plus reign of the
dinosaurs.
Yucatan Peninsula
Meteoroid and friends…
• Meteoroid = a chunk of rock or dust in space
that usually comes from a comet or a asteroid.
• Meteor = A meteoroid that enters the Earth’s
atmosphere and burns up. They are also
known as shooting stars.
• Meteorite = If the meteoroid does not burn up
and hits the Earth’s surface.
Crater Images
Types of Craters
• Some craters are volcanic craters. The top of
the volcano collapses and leaves a hole. This is
called a “caldera.” Usually, these fill up with
water and form a lake.
• Impact craters happen when “impactors”
crash onto the surface of the celestial body
and leave a hole.
How do they know?
• Scientist identify impact craters by identifying
certain key clues:
– Shape of crater (round shape)
– Overturned rocks at the edge of the crater
– Highly fractured rocks that have been ejected out
in rays outside the craters
– Chemistry of the rocks in the crater (rare
elements)
Ejecta
Famous Craters on Earth (~100)
• Barringer Crater— Arizona (1200 meters in
diameter)
• Vredefort Crater –Africa (250 - 300 km in
diameter) LARGEST CRATER ON EARTH
• Sudbury Crater ---Canada (200 km in
diameter)
• Chicxulub Crater—Mexico (170 km in
diameter)
• Woodleigh Crater—Australia (60 km in
diameter)
Changes in Craters
• Over time; ice, water, and wind weather and
erode craters which lead to changes from their
original appearance.
• Some craters have been filled with water or
soil.
Craters on Moon
• Only impact craters are found on moon.
• Estimated 3 million impact craters
• No atmosphere on the moon allows so many
meteorites to strike the surface.
• Largest craters on the moon are called
Aristarchus, Copernicus, and Tycho.
• Satellites have helped map both sides of
moon.
Moon Craters