The Earth and Space Text book Reference – The final chapter of the book!
Play ‘powers of ten’ video clip – each square is 10 times larger than the previous square. The scale of our everyday life of human interaction and personal significance is so much smaller than what exists in space in its entirety. Yet it all sits poised in perfect harmony for our very existence. The debate of is the universe’s existence solely for our existence verses is the universe’s existence and our existence a profound and immeasurable probability will perhaps only be resolved when we pass into the after life.
In the clip, the size of the square jumps from 1,000,000,000,000,000 m to just one of a more convenient unit which is the light year. How is a light ‘year’ actually considered as a unit of length rather than a unit of time as the term year would suggest? It is the distance that light travels in one year. Fill in the blanks to calculate how far light travels in one year, and hence what the length of distance one light year is. One year in seconds 31, 557, 600 Distance 9.47 x 10^15 m
Website – the size of the universe http://www.classzone.com/books/earth_science/terc/content/visualizations/es2808/es2808page01.cfm?chapter_no=visualization
Elements that make up our Solar system http://janus.astro.umd.edu/javadir/orbits/ssv.html
The scale of this diagram is completely misleading – click on the webpage to respect the emptiness of the solar system The animation is travelling at 300 times the speed of light Vast distances between planets http://www.classzone.com/books/earth_science/terc/content/visualizations/es2701/es2701page01.cfm
The rotation of the Earth, the revolution of the Earth around the Sun and the Moon around the Earth are the basis of terrestrial timekeeping. The solar day is measured using the passage of the mean Sun across the sky. It lasts 24 hours - the average interval between two successive midnights. The year and the calendar The sidereal year is the time taken for the Earth to travel once around the Sun and return to the same place with respect to the background stars. It lasts 365.256 days.
The seasons Earth's equator is tilted at 23.5º to the plane of its orbit around the Sun, the ecliptic. The axis of rotation of the Earth always points to the same direction, towards the north celestial pole. Starting in December, the northern hemisphere of the Earth is tilted away from the Sun. North of the tropics, the Sun will appear to be lower in the sky and the days will be shorter, reaching a minimum length on December 21, the winter solstice. Sunlight hits the ground at a shallow angle, so the heat is spread out over a large area, making the weather colder. In the southern hemisphere, the Sun is high in the sky and it is summer. By March, both hemispheres of the Earth have days and nights of similar length. In the north, the Sun will now be higher in the sky. At the vernal equinox on about 22 March, the Sun is above the horizon for around 12 hours over most of the Earth's surface. The northern spring and southern autumn begin this month. North of the tropics, the northern hemisphere has the longest days during June, when it is tilted towards the Sun. The Sun is high in the sky, so its heat strikes the ground at a steep angle leading to warmer weather. The Sun reaches its highest point on 21 June, the summer solstice. At this time of year, the part of the Earth to the south of the tropics is entering winter. In September, both hemispheres again have days and nights of similar length. At the autumnal equinox on 23 September, the Sun is again above the horizon for 12 hours across the globe. This month sees the onset of autumn in the northern hemisphere and spring south of the equator. In June Tromso never rotates into the Earth's shadow, experiencing 24 hours of daylight In Greenwich we experience long summer days and short nights At the equator days and nights are of equal length Sydney has short hours of daylight and long nights Equinoxes All points on the Earth experience days and nights of roughly 12 hours in length In December Tromso never rotates into daylight, experiencing continuous night Greenwich has short winter days and long nights At the equator days and nights are of equal length Sydney has long hours of daylight and short nights
In June Tromso never rotates into the Earth's shadow, experiencing 24 hours of daylight In Greenwich we experience long summer days and short nights At the equator days and nights are of equal length Sydney has short hours of daylight and long nights Equinoxes All points on the Earth experience days and nights of roughly 12 hours in length In December Tromso never rotates into daylight, experiencing continuous night Greenwich has short winter days and long nights At the equator days and nights are of equal length Sydney has long hours of daylight and short nights During the winter the Sun's radiation strikes the ground at a shallow angle and days are short. This results in cooler weather. However, during the summer the reverse is true; the Sun's radiation strikes the ground at a steeper angle, and the days are longer, resulting in warmer weather. In winter the Sun rises in the south-east and sets in the south-west. At the equinoxes the Sun rises in the east and sets in the west. In summer the Sun rises in the north-east and sets in the north-west. Questions to think about 1. Explain with a diagram why some places of the Earth have 24 hours of daylight and 24 hours of darkness for part of the year. 2. Rewrite and correct the following statement: During the summer, the northern hemisphere of the Earth is tilted towards the Sun. This means that the UK is closer to the Sun and so the weather is warmer. In winter, it is tilted away from the Sun so the UK is further away and the weather is colder. 3. Mars has an orbit where its distance from the Sun ranges from 210 to 250 million km. The southern winter takes place when it is furthest from the Sun and southern summer occurs when it is nearest. What effect will this have on the seasons in each hemisphere? 4. Why do you think the view of the stars from Earth changes with the seasons?
The energy from the Sun is responsible for driving many of the weather patterns and physical processes that here on Earth we essentially require. Plants harness the light energy by combining it with chemicals in their chloroplasts to make sugar which we in turn survive on for energy. The oceans are warmed by the heat energy from the Sun which forces currents within the water and bring changes in pressure and weather to the land. But how does the Sun produce such energy? http://www.suntrek.org/
Every second 100 TJ (10^17) of energy enters our atmosphere that’s equivalent to the output of 10 million fossil fuelled power stations, one would be right to be concerned that the Sun actually is against our existence. The coronal ejection of high energy particles, the ions it spits out towards the Earth are at speeds close to that of light with the potential to cause fatal damage similar to x-rays and gamma rays.
This radiation is propelled in the Earth’s direction and sets up Space weather, the solar winds. The magnetic effect surrounding our planet deflects the path of these particles and protects us from harm. http://www.suntrek.org/
Close to the poles in the Arctic circles there is evidence of these particles penetrating the atmosphere, although they have been slowed down and drained of energy. The spectacular lighting of the sky called Auroras are the result of the substances in the Earth’s atmosphere interacting with the particles and releasing radiation of a frequency we can sense, visible light.
Click on the weblink and talk through the notes before filling in the blanks http://www.suntrek.org/solar-surface-below/solar-energy-chain/called-fusion.shtml
It was Newton who first considered that the force that keeps our feet on the ground (or causes an apple to fall down from a tree) is the same force that causes the Earth to move in an orbit around the Sun (cannonball experiment!) The story of science episode one 42.30
A force makes a mass* change its speed or direction . All masses are attracted to each other by the force of gravity. The greater the mass, the greater its gravity. For example, of all of the bodies in the Solar System , the Sun has by far the greatest gravity because the Sun has by far the greatest mass. The closer the mass, the stronger its gravity. For example, the gravity of the Sun exerts the greatest force on its nearest planet (Mercury), the second greatest force on its second nearest planet (Venus), and the third greatest force on its third nearest planet (Earth) - and so on. Weight is the measure of the force of gravity acting on a mass. Weight is measured in newtons * Weight = Mass × Gravity Gravity is the weakest force. Gravity is such a weak force that we can only measure the gravity of very massive bodies. So, while you'll notice the gravity between yourself and the Earth , you won't notice the gravity between yourself and a crumb.
How does the size of the mass affect the force acting on the object? Neil Armstrong’s moon walk gives us evidence that the larger the mass, the larger the force of attraction. Moon walk (MJ)
Watch the orbit of a comet as it travels around the Sun, how does its speed vary with the distance from the Sun? That change of speed/velocity is caused by the force of gravity, so from Newton’s equation F =ma, we can conclude that the closer an object is to another object the greater the force acting on it (it will experience a larger acceleration) Animation of a comet’s orbital path http://janus.astro.umd.edu/javadir/orbits/ssv.html
Click on Title for applet animation hyperlink
Episode One of Wonders of the Solar System - the birth of the Sun 3.50 Pictures of the process as it unfolds - include the extra labels as the nebula develops into the protosun and protoplanets. The competing forces of gravity and particle pressure develops the rotational motion of the nebula. These patches of dense matter move with speeds that balance that of their gravitational pull to the centre. These areas with higher concentration of mass form the planets.
Earth and Space
Learning Intentions <ul><li>Recall the relative position of Earth in the vastness of space </li></ul><ul><li>Recognise the scale and components of the solar system, galaxy and Universe </li></ul><ul><li>Explain the changes in day length , season and elevation of the Sun with regards to the position and tilt of the Earth </li></ul>
What is a Light Year? <ul><li>Speed of Light = 300,000,000 m/s </li></ul><ul><li>One year in seconds = </li></ul><ul><li>Speed = distance / time </li></ul><ul><li>Distance = </li></ul>d s t
<ul><li>House Number </li></ul><ul><li>Street Name </li></ul><ul><li>Town </li></ul><ul><li>County </li></ul><ul><li>Country </li></ul><ul><li>Continent </li></ul><ul><li>Hemisphere </li></ul><ul><li>Planet </li></ul><ul><li>Solar System </li></ul><ul><li>Milky Way Galaxy </li></ul><ul><li>Universe </li></ul>What is your exact address?
Solar systems, galaxies and the Universe 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 (Basically, everything in the universe orbits around something else)
Our Solar System <ul><li>The Solar System is made up of… </li></ul><ul><li>Eight Planets </li></ul><ul><li>Moons orbiting planets </li></ul><ul><li>A large band of asteroids </li></ul><ul><li>Comets </li></ul><ul><li>The Sun (a star) </li></ul>
Our Solar System <ul><li>The set up of the Solar System is described as Heliocentric . This model has the Sun at the centre of the system with the Planets moving around in a circle or orbit around the Sun. </li></ul><ul><li>Only the Sun emits it’s own light, the other planet are visible because they reflect the light from the Sun. </li></ul>
SUNLIGHT d a y The Earth spins on its axis once every 24 hours. Day & Night N-pole n i g h t Anti-clockwise S-pole 23.5
Casablanca Philippines Antanarivo Pretoria It is 04:00 in London The Earth & Beyond : Day & Night
Learning Intentions <ul><li>Explain the changes in day length , season and elevation of the Sun with regards to the position and tilt of the Earth </li></ul><ul><li>Recall that stars are powered by nuclear fusion processes </li></ul>
The Earth & Beyond : The Seasons ( The Northern Hemisphere ) Tilted away from the Sun- Sun is low in the sky Tilted towards the Sun- Sun is high in the sky Long days Long nights Day and night the same length Day and night the same length Spring Summer Autumn Winter When it is Summer in the Northern Hemisphere, it is Winter in the Southern Hemisphere N S N S N S N S
Sunlight rays are slanted across the land Sunlight rays are almost directly on the land Why do countries close the equator not experience much change in climate from season to season?
The Earth’s surface gains most heat when the Sun is above the horizon for the most hours, and when it reaches the highest angle in the sky. This happens around JUNE 21 ST in the Northern hemisphere and DECEMEBER 21 ST in the Southern hemisphere. This midsummer day is called the SUMMER SOLSTICE. Change in Seasons
The WINTER SOLSTICE is when the Sun is at its lowest angle above the horizon and stays above the horizon for the fewest hours. Between the solstices there are two EQUINOX when the day length is equal to the night length. Change in Seasons
East- Sunrise West- Sunset June 21 st March 21 st and September 21 st Northern Hemisphere East West March 21 st Northern June 21 st December 21 st December 21 st September 21st Sunrise Sunset Choose the correct words from the box below to complete the diagram-
The Sun in all it’s shining glory! <ul><li>Click on the link below to find out how the Sun does what it does best... shine </li></ul>http://www.suntrek.org/solar-surface-below/solar-energy-chain/called-fusion.shtml
Nuclear Fusion It is possible for two hydrogen nuclei to join together to form a new nucleus containing 2 protons and 2 neutrons, a helium nucleus. Hydrogen converted to Helium In this process a little bit of mass is lost and reappears as a lot of energy (E = mc 2 ). The centre of the Sun is extremely hot (around 15 million degrees) and very dense. It is so hot that the atoms lose their electrons becoming bare nuclei. Usually, in cooler conditions nuclei would not get close enough to fuse, or join (electric forces push them apart), but with temperatures that are incredibly high, the nuclei can bang into one another so hard that they can actually fuse together and release enormous of energy.
Learning Intentions <ul><li>Understand what affects the force of gravity within the universe </li></ul><ul><li>Describe the model for the formation of the solar system . </li></ul><ul><li>Describe the Big Bang and Steady State model for the formation of the universe </li></ul>
Gravity and Newton <ul><li>Newton first came up with the idea that the force which caused an apple to fall always down from its tree was in fact the same force that keep all the planets in orbit around the Sun - gravity. </li></ul>1
Gravity - The attraction between two masses Name some objects which ‘experience’ gravity! The Earth The Moon The Sun Which of these has the most gravity? The bigger an object’s mass , the greater the effect of gravity The closer an object is to another object , the greater the effect of gravity
The bigger an object’s mass , the greater the effect of gravity The Moon walk- astronauts wore heavy boots because the effect of gravity is less on the Moon. The Moon is 1/80th the mass of the Earth and has a gravitational pull of 1/6th of the Earth
As the comet comes closer to the Sun its speed increases - a greater force must be acting to cause it to accelerate faster. The closer an object is to another object , the greater the effect of gravity
The Halley comet Edmond Halley (1656-1742), The Nucleus of the comet
Why do we have tides? The moon and the Sun cause the sea to have tides. This is because of the gravitational attraction between the Sun, moon and water in the sea. The moon has the biggest effect, as it is closer to the Earth.
Gravity <ul><li>Anything that moves with circular motion requires a centripetal force to keep it accelerating. The force acts to the centre of the circular motion </li></ul><ul><li>The force of gravity is the centripetal force between two large masses eg. The Earth and the Sun </li></ul><ul><li>The larger the mass, the larger the force of gravity and the further the masses move apart, the smaller the force of gravity </li></ul>Sun Earth Mars
The Spinning Nebula Flattens Because of the competing forces associated with gravity, gas pressure, and rotation, the nebula begins to flatten into a spinning pancake shape with a bulge at the centre.
Condensation of Protosun and Protoplanets As the nebula collapses further, gravity develops in other regions. These will become the Sun and planets, as well as their moons and other debris in the Solar System.
How did it all start? <ul><li>Read about the Big Bang and the Steady State Theory on the link below- </li></ul>http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/space/theoriginsoftheuniverserev1.shtml
Steady State Theory <ul><li>According to this theory, the Universe has always existed ; it had no beginning and will continue forever. Although the universe is expanding, it maintains its average density – steady-state – through the continuous creation of new matter. </li></ul><ul><li>Most cosmologists now reject the theory because it cannot explain background radiation or the observation that the appearance of the universe changes with time. </li></ul>
Where’s the Evidence? <ul><li>The Red Shift - Galaxies far away from our home galaxy, the Milky Way appear to be ‘red shifted’. This suggests the Universe is expanding. </li></ul>
Where’s the Evidence? <ul><li>Cosmic Background Radiation - Whenever a telescope is aimed up into our night sky there seems to be a form of microwave radiation sensed in every direction. Supposedly this is energy left over from the early stages of the Big Bang. </li></ul>
Just to be sure... <ul><li>Read some more about the Red Shift and Comic Background Radiation from the website link - </li></ul>http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/space/theoriginsoftheuniverserev4.shtml
Galaxy The Moon Nebula The Sun Aurora Match the Names to the Pictures Comet Hale- Bopp
Eclipses 1. A solar eclipse: 2. A lunar eclipse: