Transcript Year 7 Gravity and Space

Year 7 Gravity and Space
Sept 2011
Day and Night
Rotating Earth day & night – PlanetObserver
You tube video
One day is one complete
rotation of the earth
around its axis
A year
A year is one complete orbit of the Sun by the earth – 365 ¼ days
The sun is not drawn to scale here – it is much, much bigger than the earth
The seasons
The Earth is tipped over on its axis
This means that when the northern
Hemisphere is tipped towards the
Sun – it is our summer, and when
tipped away from the sun it is our
winter (and summer in the Southern
Hemisphere)
The moon
We see the
Moon by
reflected
light from
the sun
-So
We cannot
see the part
that is in
shadow.
This gives
us the
phases of
the moon
The moon
takes
approximately
28 days to
go round the
Earth once
The solar system
This is not to scale
My
Very
Easy
Method
Just
Speeds
Up
Naming
(Planets
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto)
Comets
Asteroids
Meteors
Meteorites
Asteroid belt
Kuiper belt
Moons
Rings
The planets
Students do not have
to remember planetary
information.
They need to
remember the order
of the planets
and they need to
know how to use
data to find patterns
and trends
Past ideas about the universe
Aristotle – everything went round the
Earth
Ptolemy's outstanding contribution was to develop a mathematical model of the
Solar System which could be used to calculate planet positions. He put the Earth
at the centre, but realized that the planets did not simply orbit the Earth
Copernicus put the Sun at the centre,
planets and stars orbit around
Newton
• Newton recognized
that other planets
had moons
Current ideas about the universe
We live on a small planet, orbiting a smallish star, towards the edge of a spiral galaxy of stars
we call the Milky Way. There are billions of stars within the Milky way. There are
billions and billions of galaxies, some bigger, some smaller than ours.
A spiral galaxy – like our own
This is a view of a tiny section of the sky
showing hundreds of galaxies
The expanding Universe
The speed and direction of galaxies can be measured using light. It show that the
Universe is expanding
The Big Bang Theory
If the universe is expanding now, it must have been smaller in the past
So at the beginning it must have been very, very small and then expanded outwards
very quickly – the big bang
Aliens
We have found planets orbiting other stars – they may have life on them, but that life will
be adapted to the environment of that planet and may not be like us
The pull of gravity
Satellites
To put a satellite into orbit
Get it high above the atmosphere
Give it forward thrust
The satellite will get pulled down
by gravity, but the Earth is round
and curves away. The satellite
will continue to fall towards the
Earth, but never reach it.
It will be in orbit.
orbits