Download A Quick Tour of the Solar System

A Quick Tour of
the Solar System
From our
observations using
various spacecraft
and telescopes, we
have learned that the
eight planets have a
variety of surface and
atmospheric features.
Several planets exhibit unusual
rotation.
• Venus has retrograde rotation. This means
that the planet rotates from east to west (the
reverse of Earth.)
• Uranus’axis is tilted at an angle of about
90°. Uranus rotates on its side.
Planets differ in the number of
their moons.
• Some planets have no moons - Mercury and
Venus.
• Others have many moons. Saturn appears
to have 31 and Jupiter has 61.
The range of temperature
extremes also varies from planet
to planet.
The atmospheres of each planet
vary as well.
• Only Earth and Mars have oxygen.
• The carbon dioxide atmosphere of Venus
traps heat and produces a greenhouse effect.
Planets have different surface
features.
• Mercury and Venus have mountains and
cliffs
• Mars has polar icecaps.
• Mars has volcanoes.
• Earth, Mars, Uranus and Neptune have
water.
Some planets have rings
• Jupiter, Saturn, Uranus and Neptune all
have rings.
The farther a planet is from the
sun, the less its orbital velocity.
• Orbital velocity
means the speed at
which a planet is
revolving around
the Sun.
Beyond the orbit of Neptune is an
area of space we call the Kuiper
belt.
• The Kuiper (rhymes with viper) belt is a
flattish region extending from the orbit of
Neptune to the orbit of Pluto or so.
• It contains at least 30,000 Pluto-like objects
called plutinos.
Beyond the Kuiper belt is the
outermost known area of our
solar system, called the Oort
Cloud.
• This area is spherical, and contains trillions
of comet nuclei.
There are some other objects in the
solar system.
• Asteroids are ”flying mountains” made of
rock and metals primarily found between
Mars and Jupiter in the asteroid belt.
• Comets are “dirty snowballs” of ice and gas
and dust. Some travel from the Kuiper Belt
and the Oort cloud toward the sun in an
elliptical orbit. We see the tail, or cloud of
dust and gas surrounding the comet’s core,
as it is blown by the solar wind.
• Chunks of metal or stone that orbit the sun
are called meteoroids. They may be from
the asteroid belt or from comets that have
broken up.
• If a meteoroid falls through the Earth’s
atmosphere, the streak of light it produces
as it burns is called a meteor.
• If it hits the Earth’s surface we call the
meteoroid a meteorite. Some meteorites are
large enough to produce craters on the
Earth.
Certain conditions must be met
for life to develop.
• A planet must have moderate temperatures
for billions of years for life to evolve.
• A planet must also have liquid water.
Earth is in the clement zone or
life zone of our star, the sun.
• If Earth was closer to the sun, Earth would
have been too hot to support life as we
know it.
• If Earth was more distant from the sun, it
would have been covered with frozen water,
and life might not have developed.