Solar System
Inner Planets, and Pluto
Solar System
Solar System, plus Sun
Medium Stars
Large Stars
Our Solar System
• The Earth, as we know,
is just one planet of
many in our “small”
region of space.
• The collection of
planets, asteroids,
comets, and other
natural objects that are
held by the gravity of
the sun form our solar
system.
Our Solar System – Mnemonic
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MP3s
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Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
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Our Solar System – Mnemonic
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My
Very
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Pizzas
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Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
What makes our Solar System?
• The central point in the solar system is the
Sun. The pull of its gravity is so great that
all the planets and objects within a huge
distance are held in its sway.
• Surrounding the sun are 8 or 9 planets,
thousands upon thousands of asteroids,
comets, and other astronomical debris.
• All together, this forms our solar system.
A little note on measuring.
• In astronomy, the distances we will discuss are
immense! Special units have been designed just to
compare distance.
• The Astronomical Unit (AU) is roughly the distance
from the Earth to the Sun, about 93 million miles.
• We also use light years, or the distance light will
travel uninterrupted.
• The furthest object in the solar system, the Oort
Cloud, is about 100,000 AU from the sun, or about 1
light year.
• The closest star (not including the sun )is 4.5 light
years.
Mercury
• One of the smallest planets in the solar system,
Mercury is the closest planet to the sun.
• It makes one revolution around the sun every
88 days. The planet rotates once every 58
days.
• With a distance of about 33 million miles from
the sun, Mercury is rarely seen by people on
Earth.
– It is only visible right after sunset, or before
sunrise.
Mercury
• Surface temperatures
on the planet range
from –292 to 806 F.
• Mercury has no moon,
and almost no
atmosphere.
• Mariner 10 satellite
mapped the planet in
the early 1970s.
Venus, Earth’s Sister
• Named after the
Roman goddess of
love.
• Atmosphere is
composed almost
entirely of carbon
dioxide.
– Some have predicted
that Earth will end up
like Venus if global
warming goes
unchecked.
Venus
• There is no moon
around Venus.
• Average Temp on
Venus is around 750
F.
• One year on Venus
takes 224 days.
• One day on Venus
takes 243 days!
Mars, the Red Planet
• The fourth planet from the
sun is named after the
Roman god of War.
• The red colouring comes
from iron oxide in the soil
(similar to rust).
• Mars also has polar ice
caps of carbon dioxide and
ice.
– These ice caps often
melt and reform,
depending on the
planets position to the
sun.
Mars
• Olympus Mons (left)is
the largest volcano in
the solar system.
– It stands 17 miles
above the surface.
– By comparison, Mt.
Rainier is less than
3 miles high.
Moons of Mars
• Mars has two moons
that orbit the planet.
• Both are small, and
appear almost like
asteroids that orbit the
planet.
• The moons are
Phobos (left) and
Deimos (right).
Mars
• Located 138 million
miles from the sun
(1.5 AU), Mars takes
687 days to orbit the
sun.
• One day on Mars lasts
24 hours, 39 minutes,
and 35 seconds.
Asteroid Belt
• Between Mars and
Jupiter, there is a band
of asteroids.
• The asteroid belt
consists of meteors in
a whole range of sizes:
from small dust
particles to asteroids
more than 500 miles
across.
Jupiter
• Jupiter, named for the
supreme Roman God,
is the largest planet in
the solar system.
• It is composed
primarily of hydrogen,
with some helium, and
possibly a rocky core
of heavier elements.
Jupiter
• Located about 480
million miles from the
sun, Jupiter takes 11.8
years to orbit the sun.
• One rotation of the
planet takes only 10
hours!
– This high rotation
speed causes the planet
to bulge slightly at the
equator.
Jupiter
• Jupiter is about 83,000
miles across, and has a
mass of 1.89 x 1027 kg
– To put some
perspective on that:
– Jupiter is about 22
Earths wide
– It mass is the same as
318 Earths.
– It would take 1321
Earths to fill the
volume of Jupiter!
Jupiter
• The most well known
feature on Jupiter is the
Great Red Spot.
• This feature is basically a
giant hurricane that has
lasted for centuries.
• It is about the 2 times the
size of the Earth!
• Wind speeds on Jupiter
can be over 220 miles per
hour.
Jupiter
Jupiter’s Moons
• Jupiter has 63 moons
that have been
discovered.
– Most of these are
less than 6 miles
across.
• The four main moons
are referred to as the
Galilean moons.
Jupiter’s Moons
• Io is one of the most
dramatic.
• It shows dramatic volcanic
activity, including
ongoing eruptions and
huge geysers erupting
miles above the surface.
• It is being pulled violently
by Jupiter’s immense
gravity, constantly pulling
the surface of the moon
open.
Io
Callisto
Ganymede
Europa
Saturn
• The sixth planet, Saturn is named for the
Saturnus (Greek equivalent of the Titan
Kronos, father of Zeus).
• Saturn is primarily composed of hydrogen,
with small proportions of helium and trace
elements.
• It is nicknamed the Ringed Planet, and is
the second largest planet in the solar
system.
Saturn
• Saturn is an oblate
spheroid; that is, it is
flattened at the poles
and bulges at the
equator.
• Saturn is the only planet
of the Solar System that
is less dense than water.
– That means the planet
would literally float in
water.
Saturn
• Saturn is 9.5 AUs from
the sun, or around 880
million miles.
• Saturn takes 29.5 years to
orbit the sun.
• Unusually, different
latitudes on Saturn rotate
at different rates.
– This is between 10 and
11 hours.
• It has 57 moons, the
largest being Titan.
Saturn
• An odd feature on
Saturn is a hexagonal
cloud feature rotating
at Saturn’s North Pole.
• This feature was
originally seen in the
Voyager mission in
the early 80s, and is
still there when
Cassini recently
arrived.
Saturn’s Rings
• The rings were
originally discovered
by Galileo, but he
didn’t know what they
were.
• Huygens later
idenitified them as a
ring. Then Cassini
showed they were
mutliple smaller rings.
• How exactly they
were made is still up
to much debate.
Saturn’s Rings
• Between the rotation
of Saturn and the
Earth, the rings appear
to change appearance
as the planets move.
Titan, Saturn’s Moon
• Titan is a unique moon
in the solar system.
• It is 50% larger than
Earth’s moon, and is
the only moon in the
solar system with a
dense atmosphere.
• We have sent a probe
onto the surface to
explore the possibility
of humans living on
Titan.
Titan: Images
Two more Moons of Saturn to
Note: Iapetus and Mimas
• Iapetus: two
different colours,
odd ridge around
equator
• Mimas: looks like
the Death Star
Uranus
• Discovered in 1781 by
William Herschel.
• Named after the Greek
personification of
Heaven.
• First planet discovered
without using the
human eye.
• Located about 1.8
billion miles out, or 19
AUs.
Uranus
• One revolution (year)
on Uranus is equal to
84 years on Earth.
• It rotates every 17
hours.
• Uranus is unique in
that it is tilted almost
90 degrees to its orbit.
– Its poles face the
sun! (one at a time)
Uranus
• The reason for Uranus'
extreme axial tilt is not
known.
• It is thought that during
the formation of the Solar
System, an Earth-sized
object collided with
Uranus, causing the
skewed orientation.
Uranus
• The planet is made
mostly of Hydrogen,
with some helium,
methane, and trace
amounts of acetylene.
• Its diameter is about
8.5 times that of Earth,
and it would take 63
Earths to equal its
volume.
Uranus
• Only one satellite,
Voyager 2, has ever
been to Uranus.
– It then moved on to
be the only satellite
to ever fly by
Neptune.
Moons of Uranus
• There are 27 known
moons that orbit
Uranus.
• Since it was
discovered by an
Englishman, the
moons have been
named after characters
in Shakespeare and
Alexander Pope.
Miranda
• The appearance of
Miranda has confused
astronomers since the first
photos were observed.
• It is believed to have
formed similar to Io, and
been tugged and pulled by
the gravity of Uranus, and
that now has stopped.
• Other theories?
Neptune
• The eighth planet,
named for the Roman
god of the sea.
• Discovered in 1846 by
two people,
Frenchman Le Verrier
and Englishman
Challis.
– This caused a bit of
an international
dispute.
Neptune
• One Neptunian year is
165 Earth years.
• One day is equal to 16
hours.
• Neptune is about 2.7
billion miles from the
sun, or 30 AUs.
Neptune
• The planet is composed
mostly of hydrogen, with
some helium and methane
present.
• It is about 8 Earths across,
and has a volume equal to
57 Earths.
• Neptune has some small
rings, and arcs that do not
go completely around the
planet.
Great Dark Spot
• Like Jupiter, there appears
to be a large hurricane-like
storm in Neptune’s
atmosphere.
• Called the Great Dark
Spot, it has extremely high
winds.
• The winds in the
atmosphere of Neptune
are over 900 mph most of
the time, with storms
reaching speeds of 1200
mph.
Neptunian Moons
• Neptune has 13 moons,
but only one big enough to
not look like an orbiting
asteroid.
• Triton is unique in that it
is the only moon with a
retrograde orbit.
– That is: it orbits the
opposite direction from
Neptune’s rotation.