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Our Solar System
A Journey to Our Planetary Neighbors
Ideas about the night sky have changed over time…
Earth-centered model – early Greeks thought planets, Sun, Moon and stars rotated around the Earth
Modern view – The sun is the center of our solar system All other objects in the solar system revolve around the sun in elliptical orbits at different speeds.
How did our solar system form?
A nebula of gas, ice, and dust slowly formed in space, and rotated in space.
The cloud began to contract and the matter was squeezed into less space.
The cloud became dense, heated up and triggered a nuclear fusion reaction that created the sun.
What happened next?
All leftover matter became the planets and asteroids
The four inner planets – (Mercury, Venus, Earth, and Mars) are small and rocky with iron cores
The four outer planets – (Jupiter, Saturn, Uranus, and Neptune) are large, lightweight, and composed of gases.
Inner Planets
Mercury - closest to the Sun, smallest planet Many craters and high cliffs No true atmosphere so temperatures can
range from -292 to 806° F. It orbits the sun once every 88 days and is
an average of 36 million miles from the sun.
Inner Planets
Venus – second from the sun and similar to the Earth in size and mass Mostly smooth volcanic plains Extremely dense atmosphere of clouds Carbon dioxide gas traps solar energy
resulting in temperatures between 842 to 887° F.
It is an average distance of 67 million miles from the sun and orbits every 225 days
Inner Planets
Earth – third planet from the Sun More than 70 percent of surface is covered
with water Atmosphere consists of several layers, is
mostly composed of nitrogen and oxygen, and protects the surface from meteors and Sun’s radiation
It is an average of 93 million miles away from the sun, and completes its orbit in 365.5 days
Inner PlanetsMars – fourth planet from the Sun
Called red planet because of iron oxide in rocks
Polar ice caps made of frozen carbon dioxide and water
Surface contains gullies, mountains and canyons, plains and the largest volcano in the solar system
The thin atmosphere mostly contains carbon dioxide
It is an average of 141 million miles from the Sun, and completes its orbit in 1.9 years
Asteroids and Other Objects in Our Solar System
Asteroids – rocks similar to that which formed the planets
Asteroid Belt – group of asteroids that orbit the Sun between the planets Mars and Jupiter
Comets
Comet - dust and rock particles combined with frozen water, methane, and ammonia Halley’s comet (occurs every 76 years),
Hale-Bopp (1995)
Look similar to a dirty snowballThe ice and dust vaporize as it
approaches the sun This forms a comets tail
Meteoroid, Meteor, and Meteorite
Meteoroid – small pieces of debris in space
Meteor – small meteoroid that burns up in Earth’s atmosphere (falling or shooting star)
Meteorite – meteoroid that strikes Earth
Outer Planets
Jupiter – Fifth planet from the sun and the largest in our solar system Atmosphere mainly consists of hydrogen
and helium Surface is suspected to be composed of
liquid hydrogen and helium, and may have solid core at the center
It is an average of 484 million miles from the sun and 11.8 years to complete one orbit
Has 16 moons
Outer Planets
Saturn – sixth planet from the Sun Thick outer atmosphere of hydrogen,
helium, ammonia, methane, and water vapor
Might have rocky core Rings that circle around planet are
composed of ice and rock particles It is an average of 887 million miles from
the Sun, and completes one orbit in 29.5 years
Outer Planets
Uranus – seventh planet from the sun Atmosphere of hydrogen, helium, and
methane Rotates on its side Contains thin, dark rings It is an average of 1.8 billion miles from
the sun, and completes one orbit in 84 years
Outer Planets
Neptune – eighth planet from the Sun Atmosphere is similar to that of Uranus Storms on Neptune reveal an active and
rapidly changing atmosphere It is an average of 2.8 billion miles from the
sun, and completes its orbit every 165 years