Download The Earth and Beyond

The Earth and Beyond
Contents
The Solar System
 Stars
 Solar Systems, Galaxies & the Universe
 Comets
 Life Cycle of Stars
 Red-Shift
 History of the Universe
 Future of the Universe
 SETI

The Solar System
My
Very
Efficient
Mind
Just
Stores
Up
Nine
Planets
Stars

Stars are burning balls of gas e.g. our Sun

Stars give out light

This light reflects off planets so we can see them

Planets are much smaller than stars
… but they seem much bigger as they are much closer

The 9 planets orbit the sun, Earth orbits the Sun once a year
Stars

Stars are burning balls of gas e.g. our Sun

Stars give out light

This light reflects off planets so we can see them

Planets are much smaller than stars
… but they seem much bigger as they are much closer

The 9 planets orbit the sun, Earth orbits the Sun once a year
Solar Systems, Galaxies & the Universe
Our Sun is one of
millions of stars that
orbit the centre of the
Universe
The Milky Way is one of
more than a billion
galaxies in the Universe
The Universe is expanding
Comets
Comets appear every few years
Comets have highly elliptical orbits around the Sun
Tail is pushed away from sun by solar pressure
Tail is made of ice and rock
Comets are visible when they are close to the Sun
A comet’s orbit is fastest near the Sun due to the Sun’s
gravity. It slows as it moves further away from the Sun
Life Cycle of Stars
Layers of
dust & gas
are ejected
clouds of
dust & gas
HHe
heat & light
ejectedstar
H runs
outswells
red = cooler
cools and
contracts
dense core =
neutron star
explode
supernova
or black hole
(crushes atoms!)
Red-Shift

Light from distant galaxies is shifted towards the red end of
the spectrum

Frequencies become lower as they move away (like the
Doppler Effect for sound)

Further away = greater red-shift

Universe is expanding

Also evidence from microwave
radiation (background radiation)
that Universe is cooling
History of the Universe

1. Steady State Theory


Universe has always existed…
and Universe will always exist

No convincing evidence

Not much support for the Steady State Theory
History of the Universe

2. Big Bang Theory

Universe was compressed and exploded – Big Bang

Occurred 15 billion years ago

Estimated by current rate of expansion

Expansion is slowing due to gravity
Future of the Universe
According to the Big Bang Theory…

1. Expand Forever
If too little mass for gravity to stop expansion…
 Universe will expand and spread out into eternity


2. Big Crunch

If enough mass to stop expansion, universe will contract
Big Crunch!
Big Crunch would produce another Big Bang… and so on!


SETI
Scientists search for extra terrestrial intelligence

Radio Signals
SETI looks for radio wavelength signals being sent to Earth
 These signals can only be sent by a transmitter


SETI has been running for 40 years… not found anything
Now searching for laser signals too!

Robots Collect Photos and Samples

Spacecraft are sent to planets to look for microorganisms
Collect samples and take photos
Scientists analyse samples and look for fossils etc.



Summary
Solar system – 9 planets & 1 star
 Stars emit light, planets reflect this light
 Solar systems are in galaxies which are in the Universe
 Comets (rock and ice) have long elliptical orbits around Sun
 Life cycle of stars – differs for massive & small stars
 Red-shift – evidence for fast expansion of galaxies
 History of the Universe – Big Bang or Steady State
 Future of the Universe – Big Crunch or Eternal Expansion
 SETI – Radio signals, laser signals, collect photos & samples
