Transcript Our Solar System

Our Solar System
Planets
• An object that orbits one or more stars
and is not a star itself
• Spherical
• Does not share its orbit with another
object
• Inner planets (Terrestrial planets) are
Mercury, Venus, Earth, and Mars)
• Outer planets (Gas planets) are Jupiter,
Saturn, Uranus and Neptune.
ORDER OF THE PLANETS
My
Mercury
Venus
Very
Educated
Earth
Mars
Mother
Just
Jupiter
Served
Saturn
Us
Uranus
Nuts
Neptune
Planetary Motion
• Venus and Mercury stay near the Sun and
can only be seen in the early morning or
early evening.
• Mars, Jupiter and Saturn move westward
along with the fixed stars due to Earth’s
rotation.
• Retrograde motion happens when Earth
catches up with and passes an outer planet
in its orbit. It appears that the planet makes
a looping motion in the sky.
Distances Between Planets
• Planets lie so far apart that using
kilometers to measure it, is not
meaningful.
• Astronomers use astronomical unit (AU),
which is equal to the distance between
Earth and the Sun (150million km)
• The average distance between the Sun
and an object that is orbiting it is called
the orbital radius.
Mercury
• Craters, rocky
• Small (only a bit
larger than our
moon)
• No atmosphere so
large temperature
differences between
day and night
• No moons
Venus
• Size and composition similar
to Earth
• Shrouded in thick clouds
• Constantly rains sulfuric acid
(acid rain)
• Atmosphere contains CO2
and nitrogen.
• Some areas that are flat,
volcanoes, cracks called rifts.
• Hot because the atmosphere
traps the heat.
• No moons
Earth
• Only planet that has
life (so far)
• Lots of water
• Atmosphere:
nitrogen, oxygen
and water vapor
mainly.
• Surface is constantly
changing.
• 1 moon
Mars
• Red because the iron
in the rock
• Volcano 3 times larger
than Mt Everest
• Very deep canyon
(8km deep)
• Strong winds
• 2 polar ice caps
• Thin atmosphere
made mainly of CO2
• 2 moons
Jupiter
• Largest
• Great Red Spot: a storm
of hydrogen and helium
clouds.
• Shortest days of all
planets (10hours)
• Rings made of ice
particles that are very
thin.
• 61 moons
Saturn
• Elaborate system of rings
made of ice particles
• Rings are 250 000km
wide
• Composed of mainly
hydrogen and helium
• 60 moons
Uranus
• Ring system made
of ice and dust
• Methane gas in its
atmosphere (bluegreen colour)
• Atmosphere also
has hydrogen and
helium
• Unusual rotation flipped on its side
• 27 moons
Neptune
• Atmosphere is
similar to Uranus.
• Very thin ring
system made of ice
particles.
• 13 moons
Trans-Neptunian Objects
•Objects that circle the Sun
beyond the orbit of Neptune
•Found in the Kuiper Belt
•Astronomers think that it is
made of fragments left over
from the formation of the
solar system.
•Pluto is found in the Kuiper
Belt and is known as a
dwarf planet.
Oort Cloud
• At the farthest
reaches of the Sun’s
gravitational
influence is a
spherical cloud of
icy fragments of
debris called Oort.
Comets
• Most start in the Kuiper Belt and
the Oort cloud.
• Sometimes the comet gets too
close to Jupiter.
• Jupiter’s gravitational force will
either capture the comet or nudge
it closer to the Sun
• When it gets close to the Sun, the
radiation from the Sun releases
the gases and particles in the
comet.
• The wind from the Sun make the
tail of the comet.
Asteroids
• Small, non-spherical
objects that are
thought to be debris
left over from the
formation of the
solar system.
• Most are in the
asteroid belt found
between Mars and
Jupiter
Meteoroids vs Meteors vs
Meteorites
• Meteoroids: Pieces of rock
moving through space.
• Meteors: a meteoroid that
hits Earth’s atmosphere and
burns up due to atmospheric
friction.
• Meteorites: a meteoroid that
is large enough to pass
through Earth’s atmosphere
and reach the ground without
being totally burned up.
The Impact of Impacts
• An asteroid about the
size of a mountain
struck Earth 65 million
years ago.
• There were huge
changes on Earth
because of it.
• Extinctions: dinosaurs
• Impact craters (Nunavut
and Arizona)
• Probably created huge
winds and falling rock.