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Chapter 11
11.2 The Sun and the Planetary System
Our solar system is full of planets, moon, asteroids, and
comets, all in motion around the Sun. Most of these
components are separated by great distances. Each
planet has its own distinct characteristics. Comets, icy
debris, and dwarf planets travel at the outermost
reaches of our solar system.
Formation of the Solar System
Our solar system was formed more
than 4.5 billion years ago. As the Sun
burst into existence, the leftover
material combined to form eight
planets and numerous other
planetary bodies: moons, asteroids,
and comets. Closest to the Sun are
the inner planets (terrestrial
planets) and further away are the
outer planets (gaseous giants).
The SUN
The sun contains more than 99% of all the
solar systems mass. The composition of our
star is mainly hydrogen gas, the most
common element in space. The hydrogen in
the sun fuses with helium and radiates this
energy outward.
The SUN
The sun is a complex system of bubbling gases
that occasionally send out spectacular explosions
and violent solar flares. It has no solid surface
but many distinct features.
Solar Winds
Energetic gases in the corona are ejected in a
sudden burst. When these high energy particles
rush past the Earth they create “solar winds.”
These winds are deflected by the magnetic field
around the earth’s poles. This is what causes our
Northern Light shows. Sometimes these winds
can disrupt satellites and temporarily knock out
power supplies to Earth.
The
PLANETS
To be considered
a planet the body must
orbit one or more stars,
be large enough that its
own gravity holds it in a
spherical shape, and be
the only body occupying
the orbital path.
MERCURY
o
o
o
o
o
closest planet to the Sun
smallest, slightly larger
than our moon
no significant atmosphere
extreme temperatures
400oC to -183oC
changes in temperatures
cause contraction and
expansion of crust forming
many craters and cracks
VENUS
o
o
o
o
o
closest to Earth
similar in composition to Earth
atmosphere is almost all carbon dioxide
thick clouds of sulphur dioxide cover the
planet
planet has volcanoes, lava flows, cracks and
rifts
EARTH
o
o
o
o
o
blue planet, 3rd rock from the Sun
suitable atmosphere and temperatures
water found in all 3 states (solid, liquid, gas)
water covers nearly 3/4 of the entire planet
atmosphere is almost completely N2 and O2
MARS
o
o
o
o
o
o
o
“Red Planet” because of the iron content in
soil
half the size of Earth but same surface area
has a volcano 3x the height of Mt Everest
has 8 km deep canyon that stretches from
Vancouver to Toronto
thin atmosphere of carbon dioxide
has winds up to 900km/hr
dust storms and two polar ice caps
JUPITER
o
o
o
o
o
largest planet in solar
system
gas giant
mass 2.5 times greater than
all planets combined
great “Red Spot” (visible
from Earth) is a storm raging
in clouds of hydrogen and
helium that forms the outer
layers
has the shortest day of any
planet, turning once on it’s
axis every 10 hrs
SATURN
o
o
o
gas giant identified by the elaborate system of rings
formed from ice particles
ice rings are 250,000 km wide and as thin as 10m
planet is composed mainly of hydrogen and helium
URANUS
o
o
o
o
o
fourth most massive planet, another gas
giant
Similar composition to Jupiter and
Saturn
Also has a system of rings made of ice
and dust
Blue colour is from the methane gas in
its atmosphere (methane absorbs red
light)
it orbits differently than other planets
because its axis is tilted
NEPTUNE
o
o
o
o
o
outermost planet and 3rd most massive
dark blue colour due to methane similar
to Uranus
also has a ring system but is faint
when voyager 2 flew past the planet it
noticed a spot similar to Jupiter, which is
likely a storm cloud
Hubble telescope has discovered another
storm cloud near the northern
hemisphere
The MOON
All planets except Mercury and Venus have
one or more orbiting companions. Over 150
moons have been discovered orbiting planets
in our solar system. Astronomers call these
orbiting companions “satellites.”
ASTEROIDS
Asteroids are small bodies that are leftover
remains of the formation of the solar system.
Most asteroids orbit the sun in a band
between Mars and Jupiter. They range in size
from grains of sand to 1,000 km wide like
“CERES.”
COMETS
Comets are often referred to as “dirty snowballs.”
They are composed of ice, rock, and gas. Space
probes have found that there is more rock than
once thought. They originate from the Kuiper Belt
and the Oort Cloud. Once they get close enough to
the sun we can see the trail of gas, ice and dust
streaming behind.
Trans-Neptunian Objects
Anything that orbits the sun past
Neptune are considered TransNeptunian objects. Scientists believe
there are about 23 objects orbiting in the
Kuiper belt .
Some of these objects or dwarf planets
are:
 Pluto
 Ersis in the Kuiper belt
Oort Cloud
At the farthest reaches of the Suns
gravitational influence is a spherical
cloud of small icy fragments of debris
called the Oort Cloud. It is another
source of comets. It is approximately
1/4 the distance to the next closest
star.
Section 11.2 Quiz
11.3 Measuring Distances in Space
Astronomical units are used to measure distances
within the solar system. Light years are used to
measure distances to other bodies far beyond our
solar system. Distances measured from Earth to
some bodies can be determined by using
triangulation and parallax.
How BIG is SPACE?
Section 11.3 Quiz