Transcript E-7 Notes

Science 9: Space
Topic 7 - The Solar System
Basic Details
► The
solar system is centered on the sun. The
sun provides the gravity that keeps the planets
in their orbits. Just like anything else the solar
system will not last forever. The sun will go
nova in about 5 billion years and when it does
some of the planets will fly off into space.
► The solar system is broken up into four main
parts: The sun, the inner rocky planets and
their moons, the outer gas-giant planets with
their moons, and Pluto and its moon Charon.
The Sun
► The
sun is an average sized star with an
average amount of brightness. It’s middle
aged. The sun is 1.4 million km wide
(compared to 13000 km for the Earth).
The Sun’s a Nuclear Fusion Reactor
► The
Sun is made up of mostly hydrogen. The sun
is so large that its gravity causes a nuclear fusion
reaction producing huge amounts of energy.
Hydrogen atoms fuse together to form Helium
atoms. This reaction produces all the heat and
light energy that keeps the Earth alive. Eventually
the hydrogen atoms in the sun will run out and
the sun will start fusing helium atoms together.
This process keeps going until the elements
become heavy enough to resist fusion, the sun
starved of its fuel explodes off its outer layers,
leaving a cold white dwarf star behind.
The Inner Rocky Planets
► The
inner planets are smaller than the outer
planets and are rocky in composition.
► The inner planets consist of Mercury, Venus, the
Earth, and Mars. Only the Earth and Mars have
natural satellites.
► Because these planets are much closer to the
Earth they have been studied more closely by
spacecraft than the outer planets. Mars especially
has been very well studied. It currently has three
spacecraft doing remote sensing on it from orbit
and two working rovers on its surface.
The Moon
► The
first celestial body that was studied by
and visited by humans is the Moon. Humans
first landed on the Moon in 1969. The Moon
has helped life on Earth by acting as a kind
of shield protecting the Earth from many
meteor impacts.
The Outer Gas-Giant Planets
► These
planets are much larger, and much farther
away from the Earth. In fact NASA still doesn’t
have rockets powerful enough to reach them in a
reasonable amount of time, so gravitational assists
are used to reach them.
► Outer planets are made up of mostly gaseous
atmosphere. They do have a rocky or liquid core.
The gas giants are Jupiter, Saturn, Uranus, and
Pluto the Planetoid (or Dwarf Planet)
► Pluto
doesn’t fit into either of the first two groups.
It’s the smallest planet in the Solar System, and
it’s the furthest out. No spacecraft has ever visited
the planet, but one is on its way and is speeding
towards Jupiter to get a gravitational assist or
► Scientists aren’t sure, but suspect that it’s made
up of a mixture of rock and methane ice. Many
scientists feel that Pluto shouldn’t even count as a
planet at all.
Pioneer and Voyager Space Probes
and the ‘Golden Disks’
► There
are four
spacecraft that NASA
scientists sent out in
the 1970s. All four
have either reached or
passed the edge of the
solar system. They are
now traveling in interstellar space. These
probes travel around
60000 km/h.
Pioneer and Voyager Space Probes
and the ‘Golden Disks’
Because the speed of light is finite, the time-lag to get radio
signals from the satellite to radio antenna on Earth is increasing
everyday. As of now it takes 24 hours for radio signals from the
spacecraft to arrive on Earth.
On the Voyager probes NASA scientists put two golden disks on
them with a summary of information on the Earth and the
human race. It was designed as a friendly greeting to any
aliens who happen upon the Voyager spacecraft. It contains:
A diagram of a human man and woman.
Some mathematical formulas and proofs: showing that we’re an
advanced species.
Some classical and modern (1950s Chuck Berry) music tracks in
CD format.
Triangulation instructions for these aliens to visit us.