Space and its Mysteries

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Space and its Mysteries
(Edexcel)
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There are nine planets in our solar system
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
My Very Easy Method Just Speeds Up Naming Planets
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We see planets and the moon because they reflect
sunlight
The sun is different it produces its own light.
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The Earth orbits the sun
every year (365 1/4 days)
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The Earth is kept in orbit by 2 things
Gravity
and by the fact that it is moving at a high
velocity
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The Earth spins on an axis
Because of this spin the sun and stars appear to
move across the sky
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Temperature
The average temperature of the Earth stays
roughly constant due to our atmopshere
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The moon
The moon orbits the Earth every 28 days at a
distance of 380,000km.
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Solar systems, galaxies and the Universe
(Basically, everything in the universe orbits
around something else)
OUR SUN is one of millions of stars that orbit
the centre of
THE MILKY WAY, which is one of a billion galaxies
that orbit AND move away from the centre of
THE UNIVERSE
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The Light Year
Distances in space are so big that they are
measured in units called light years
1 light year the distance travelled by light in
one yar
If light travels at 300,000,000m/s how far is one
light year?
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Gravity
Gravity is an attractive force that affects
anything with mass
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Gravity on different planets
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Weightlessness
When astronauts orbit the Earth they feel
weightless. This is because their apparent
outward force produced by their circular motion
balances gravity.
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Weight vs. Mass
Earths Gravitational Field Strength is 10N/kg.
In other words, a 1kg mass is pulled downwards by
a force of 10N.
Weight Mass x Gravitational Field Strength (in
N) (in kg) (in N/kg)

• What is the weight on Earth of a book with mass
  2kg?
• What is the weight on Earth of an apple with mass
  100g?
• Dave weighs 700N. What is his mass?
• On the moon the gravitational field strength is
  1.6N/kg. What will Dave weigh if he stands on
  the moon?

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Force and acceleration
If the forces acting on an object are unbalanced
then the object will accelerate, like these
wrestlers
Force (in N) Mass (in kg) x Acceleration (in
m/s2)
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Force, mass and acceleration

• A force of 1000N is applied to push a mass of
  500kg. How quickly does it accelerate?
• A force of 3000N acts on a car to make it
  accelerate by 1.5m/s2. How heavy is the car?
• A car accelerates at a rate of 5m/s2. If it
  weighs 500kg how much driving force is the engine
  applying?
• A force of 10N is applied by a boy while lifting
  a 20kg mass. How much does it accelerate by?

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More on weightlessness
If you move far enough away from the Earth you
experience true weightlessness. Astronauts can
overcome this by spinning their spacecraft to
create artificial gravity.
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Other interesting things...
Spinning a spacecraft also ensures even exposure
to the sun (temperatures in space can be as cold
as -270OC). Astronauts have to exercise for 2
hours a day to avoid muscle wastage and heart
attacks when they return. They also take all the
required oxygen with them. For longer journeys
(e.g. Mars) plants could be used as an oxygen
source.
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Rockets
When a rocket flies away from Earth the force
needed to keep it accelerating decreases
Words gravity, smaller, large, lighter
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Escape Velocity
Theoretically, if you throw something hard enough
it will escape Earths gravitational field. This
is escape velocity.
On Earth, escape velocity is around 11km/s. It
is larger on denser planets and smaller on bigger
planets.
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Black Holes
A black hole is an object that is so small and
dense that its escape velocity is greater than
the speed of light. In other words, not even
light can escape its gravitational pull.
Fascinating
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Benefits of Space Research
Although space research has some direct benefits,
there are many other inventions that have come
from space research

• Imaging technology, such as mobile phone cameras
  and advanced ultrasound scanners
• Satellite technology for phone calls, SatNav
  systems etc
• Weather forecasting
• Smoke detectors, hang gliders, batteries, sports
  bras and other inventions also owe their creation
  to space research.

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Life on Other Planets
Research task
Is it likely that other planets in our solar
system could have life? Explain your
answer. Extend your inquiry to other solar
systems what criteria must be met in order for
a planet to potentially have life on it?
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SETI
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Does other life exist?
ET is it possible?
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Searching for ET
In any scientific enquiry you have to OBTAIN some
evidence and then ANALYSE it (just like your
coursework). Consider searching for
extra-terrestrial life on Mars

• OBTAINING EVIDENCE
• Fly to Mars yourself (takes ages)
• Use robots to bring back samples (not very
  reliable)
• Use robots to take pictures and send them back
  (also not very reliable)

• ANALYSING EVIDENCE
• Use microscopes to search for fossilised remains
  inside the samples
• Place the sample in a container and monitor
  changes in the environment due to living
  organisms being present in the sample

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The formation of the universe
There are two main theories about how the
universe started
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The end of the Universe
There are some theories about how the universe
will end
The big crunch if there is too much mass
(i.e. too much matter) the universe will collapse
under its own gravity. It may then do another
big bang this is the oscillating universe
theory.
Expanding Universe if there isnt enough mass
in the universe then it will just keep on
expending forever.
If there is just the right mass in the universe
then it will reach a fixed size.
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Evidence for the Big Bang
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If you pass the light through a gas something
different is seen
Some wavelengths of light are absorbed by the gas
an absorption spectrum.
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If the light source is moving away the absorption
spectra look a little different
helium
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The absorption lines have all been shifted
towards the longer wavelength end (red end)
This is called red shift. The faster the light
source moves the further its light will be
shifted
A similar effect happens with sound this is
called The Doppler Effect
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Light from different stars and from the edge of
the universe also shows this red-shift. This
suggests that everything in the universe is
moving away from a single point.
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Red shift summary
Light from other galaxies has a longer _________
than expected. This shows that these galaxies
are moving ____ from us very quickly. This
effect is seen to a greater extent in galaxies
that are _______ away from us. This indicates
that the further away the galaxy is, the ______
it is moving. This evidence seems to suggest
that everything in the universe is moving away
from a single point, and that this process
started around 15 _____ years ago. This is the
____ ________ Theory.
Words to use faster, away, big bang, billion,
wavelength, further
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Comets
Comets are balls of dust and frozen gas. They
have very elliptical orbits
As the comet approaches the sun gases evaporate
from it, forming a tail. This tail always
faces AWAY from the sun.
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Asteroids
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The Life Cycle of a Star
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Stage 1 Nebulae
A nebulae is a collection of dust, gas and
rock. Some examples of nebulae
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Dark nebula
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Emission nebula
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Planetary nebula
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Reflection nebula
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Stage 2 Protostar
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Stage 3 Main Sequence
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Stage 4 Red Giant
Eventually the hydrogen and helium will run out.
When this happens the star will become colder and
redder and start to swell
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Stage 5 The Death
What happens at this point depends on the size of
the star 1) For SMALL stars the red giant will
collapse under its own gravity and form a very
dense white dwarf
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2) If the star was a RED SUPERGIANT it will
shrink and then EXPLODE, releasing massive
amounts of energy, dust and gas.
This explosion is called a SUPERNOVA
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The dust and gas on the outside of the supernova
are thrown away by the explosion and the
remaining core turns into a NEUTRON STAR.
If the star is big enough it could become a BLACK
HOLE.
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Stage 6 Second generation stars
The dust and gas thrown out by a supernova can be
used to form a new star