Download The Solar System and our Universe

The Solar System and our
Universe
Additional Information
P9 – Describe the composition of
the solar system.
The Solar System contains the following parts
• Star (Sun)
• Planets
• Dwarf planets
• Natural satellites
• Comets
• Meteors
• Asteroids
• Moons
Sun
• This is a star at the centre of the solar
system.
• The heat & light from the sun is caused by
nuclear reactions in its centre.
• It is one of may billions of stars which form
the Milky Way galaxy.
• Gravity is the force that keeps the stars
together in the galaxy.
Planets
• They are large balls of
rock / gas that travel
around the Sun in ellipses.
• There are 8 planets in the
solar system
• They reflect sunlight
• Inner planets (closet to the
sun) – Mercury, Venus,
Earth & Mars.
• Outer planets (further
away) – Jupiter, Saturn,
Uranus, Neptune.
• Planets orbit around the
stars.
• Pluto is not strictly a
planet.
• They often have moons
orbiting them. They are
much smaller than their
planets.
• Planets are held in orbits
by the gravitational pull of
the Sun.
Dwarf planets
• Orbit the Sun, smaller than planets.
• Less effect on their surroundings than
planets.
• Pluto is a dwarf planet.
Natural satellites
Comets
• Orbit the Sun in elongated elliptical orbits.
Taking them very far away & then back in
close.
• Made of balls of ice & dust.
• Orbit different planes from the planets.
• When the comet approaches the sun , its ice
melts, leaving a bright tail of gas & debris.
• The comet speeds up as its approaches the
sun. The pull of the Sun’s gravity is stronger
the closer you are to the Sun.
Comets
• Travel through space
• When close, the comet appears to have a tail
streaking out from behind it.
• May be left-overs from when the solar
system was formed
Meteors
• They are also called – ‘Shooting Stars’.
• They occur when rocks burn up as they pass
through the Earth’s atmosphere.
Asteroids
• Similar to planets & dwarf planets.
• Much smaller
• Found orbiting between Mars and Jupiter.
Orbit the Sun in the asteroid belt.
• Fragments of rock, up to 1000km in
diameter.
• Formed at the same time as the solar
system.
Moons
• Smaller than their planets, found close to
the planet.
• Made up of smaller lumps of rock that
travel around planets
• Some planets have several moons
Identify evidence that shows how
the universe is changing.
P10
• Red Shift (galaxies moving away from
each other)
• Cosmic background radiation,
• Star galaxies
Red Shift
• This is the light from far-away galaxies, the
lines in the spectra were redder than
expected.
• The red shift is bigger when a galaxy is
further away from Earth.
• All galaxies were moving away from Earth,
the most distant galaxies are moving faster.
• The universe is expanding!
• More distant galaxies have greater red-shifts
than near ones.
Cosmic Background Radiation
• 40 years ago faint radiation was detached
coming from all directions of space.
• This is called : Cosmic background
radiation.
• Confirmed the theory that the universe
began as a ‘big bang.’
Star Galaxies
• Telescopes (Hubble Space Telescope) take
photos of stellar explosions & nebulae.
• Provided evidence that throughout the
universe stars are dying, and new stars &
galaxies are constantly forming.
Big Bang (M5)
• Everything from the universe originated
from the same point & then exploded apart.
• Since the explosion the universe has been
expanding & cooling.
• The big bang occurred – 11 – 18 billion
years ago.
Big Bang (M5)
• This theory, suggests that all the matter & energy
in the Universe must have compressed into a very
small space.
• Then it exploded & started expanding.
• The expansion is still occurring.
• The current rare of expansion of the Universe to
estimate its age
• The estimate might not be very accurate, it’s hard
to tell how much the expansion has slowed down.
Big Bang (M5)
• The rate of which the expansion is slowing
down is an important factor in deciding the
future of the Universe.
• Without gravity the Universe would expand
the same rate forever.
• All the masses in the Universe attract each
other & tend to slow the expansion down.
The ‘Steady State’ Theory (M5)
• This states that the universe has always
existed as it is now, & it always will do.
• The Universe appears pretty much the same
everywhere.
• It explains the apparent expansion by
suggesting that matter is being created in
the space as the Universe expands
How was the solar system
formed? (M5)
• Stars form from swirling clouds of dust &
gases in space – Nebulae.
• Gravity makes the centre of the cloud clump
together.
• The clump is so massive that gravity
crushes the particles very, very tightly.
• The centre heats up to million of degrees.
• This is hot enough for nuclear fusion
reactions to ignite
• The star starts to shine & gives out heat.
• As the star forms, the outer edges of the
cloud are still swirling around the centre.
• The particles of dust & gas may clump
together, attracting other particles.
• The gravity is not strong enough for nuclear
reactions to ignite.
• Strong enough to hold the particles together.
• This is how planets are formed.
• Their movement means that the orbit the
star, and the solar system is complete.
• The Universe is the whole of space & includes
billons of groups of stars – Galaxies.
• Galaxies – each with billion of stars, many with a
solar system.
• Our galaxy is called Milky Way.
• In a stars lifetime, it changes size & colour as
different reactions take place in its core.
• Some stars explode, flinging out elements that
have formed in the nuclear reactions in their core.
• These particles form new Nebulae – Where new
stars will form.
What does the evidence tell us
about the origin of the Universe?
(M5 & M6)
• Scientists believe that the red shift evidence tells
us that at some point in time, billions of years ago,
all the mater & energy in the Universe was
concentrated in the same place.
• A massive explosion tool place – Big Bang.
• It flung all the matter & energy apart
• As the new Universe cooled, particles formed &
clumped together, making star & galaxies
• The Universe has been expanding & cooling
down.
Is the theory right? (D5 & D6)
• The discoveries of the red shift of distant galaxies
& the cosmic background radiation suggest that
the Big Bang theory is right.
• There is no strong counter-evidence to say it is
wrong.
• It cannot be proved, but most scientists believe the
Big Bang took place.
• We will never know what happened before the Big
Bang or what caused it.
Is the theory right? (D5 & D6)
• The evidence that the Universe is still changing is
strong.
• Photos can record the changes clearly.
• They can not tell us what is happening now, but
what happened in the past.
• Light from stars takes years to reach us & we have
even detected light from stars formed soon after
the Big Bang that has taken 14 billion years to
reach us.
The Future of the Universe
(D5 & D6)
•
The fate of the Universe depends on how
fast the galaxies are moving apart & how
much total mass there is in it.
• There are 2 ways the Universe could go:
1. Big Crunch
2. Oblivion
Big Crunch
• Mass everywhere is attracted together by gravity.
• This could slow the Universe’s expansion.
• If there is enough mass compared to how fast the
galaxies are currently moving, the Universe will
eventually stop expanding & then begin to
contract
• This would end in a BIG CRUNCH.
• The Big Crunch could be followed by another Big
Bang & then endless cycles of expansion &
contraction
• This is called the Oscillating Universe theory.
Oblivion
• Too little mass in the Universe to stop the
expansion, it could expand forever with the
Universe becoming more & more spread
out into eternity.
What does the evidence tell u
How the universe is changing
(D5 & D6)
• The universe will keep on expanding - The
galaxies move fast enough to overcome the forces
of gravity acting between them.
• The expansion will slow down & stop – The
galaxies will remain in a fixed position, The
gravitational forces will exactly balance the
‘expansion forces.
• The universe will start to contract – The force
of gravity acting between the galaxies will
overcome the forces causing expansion & pull
them back together again.