Exploring Our Solar System

Edwin Hubble was one of the first people to actually realise what a galaxy is, the measurement of the “Hubble Tuning Fork” Classification scheme shows how round or rightly wound their “arms” are. E0 means that an elliptical galaxy is extremely round,

whilst E7 is flat. However not all galaxies can be classified in this manner as there are several irregular shapes usually caused by 2 different galaxies having collided or are being influenced by the other’s gravitational force. Edwin Hubble was one of the first people to actually realise what a galaxy is, the measurement of the “Hubble Tuning Fork” Classification scheme shows how round or rightly wound their “arms” are. E0 means that an elliptical galaxy is extremely round,

whilst E7 is flat. However not all galaxies can be classified in this manner as there are several irregular shapes usually caused by 2 different galaxies having collided or are being influenced by the other’s gravitational force. The Milky Way is approximately 100,000 LY in diameter and the stars we see could be light years away. The closest to Earth of course being the Sun, the next being Proxima Centauri, 4.2 LY away. The Milky Way, as with two thirds of known galaxies, is spiral shaped with the central point causing the immense gravitational force required to pull such an immense amount of gas, stars and dust being a black hole.

As before, most galaxies are formed in a spiral shape and can contain 10 million to 10 trillion stars, and the cloud like shapes within the galaxies are caused by condensed dust and rock being pulled in by the black hole’s gravitational force. Even though most are spiral shaped, the rest of the majority are elliptical, with the rare tooth pick or ring shaped galaxies. The classification of galaxies was developed by Edwin Hubble, The Milky Way is approximately 100,000 LY in diameter and the stars we see could be light years away. The closest to Earth of course being the Sun, the next being Proxima Centauri, 4.2 LY away. The Milky Way, as with two thirds of known galaxies, is spiral shaped with the central point causing the immense gravitational force required to pull such an immense amount of gas, stars and dust being a black hole.

As before, most galaxies are formed in a spiral shape and can contain 10 million to 10 trillion stars, and the cloud like shapes within the galaxies are caused by condensed dust and rock being pulled in by the black hole’s gravitational force. Even though most are spiral shaped, the rest of the majority are elliptical, with the rare tooth pick or ring shaped galaxies. The classification of galaxies was developed by Edwin Hubble, The Universe is a vast expansion, beyond the imagination of anyone, it consists of billions galaxies, which consist of enormous groups of stars. It can also be defined everything in existence.

Our galaxy is called “the Milky Way” as illustrated to the right, with the sun being placed deep within the Orion Arm. Even though it is the centre of our orbit it is still about 26,000 light years (LY) away from the centre of the galaxy (Light years, is the distance light travels in a year, and light travels at 299,792,458 metres per second.) The Universe is a vast expansion, beyond the imagination of anyone, it consists of billions galaxies, which consist of enormous groups of stars. It can also be defined everything in existence.

Our galaxy is called “the Milky Way” as illustrated to the right, with the sun being placed deep within the Orion Arm. Even though it is the centre of our orbit it is still about 26,000 light years (LY) away from the centre of the galaxy (Light years, is the distance light travels in a year, and light travels at 299,792,458 metres per second.) http://www.atlasoftheuniverse.com/galaxy.html

http://www.atlasoftheuniverse.com/galaxy.html

Our Solar system, Planets, Orbits and Centripetal Force
Our Solar system, Planets, Orbits and Centripetal Force

Comets
A Comet is a small body within the Solar System that contains ices and rocks, the centre of a comet is called the nuclei, which is a small part of the comet, this is the part that contains the rocks and ices and as a Comet ages it loses these ices, when a comet loses the it’s ice it is deemed dead as it can’t produce any feature but the nuclei. The other features of a comet are only present when it is closer to the Sun than Jupiter, when a comet gets this close to the Sun, the heat melts the ice within the Nuclei and causes a glowing head to form, known as the coma, and because the ice of the nuclei are composed of many different molecules some of these molecules escape the nuclei’s gravitational force easily causing a “Hydrogen Envelope” or “Hydrogen Cloud”. Most comets usually have two tails, and usually one is much brighter than the other. The tails form as a result of the sun’s solar wind – the stream of charged particles that emanate from the sun. The Solar Wind causes parts of the comet to become separated causing a narrow trail. This is how comets lose most of their mass and ice. Whilst in the orbit of the sun the comet speeds up as the strength of gravity is increased as it’s closer to the source.

A Comet is a small body within the Solar System that contains ices and rocks, the centre of a comet is called the nuclei, which is a small part of the comet, this is the part that contains the rocks and ices and as a Comet ages it loses these ices, when a comet loses the it’s ice it is deemed dead as it can’t produce any feature but the nuclei. The other features of a comet are only present when it is closer to the Sun than Jupiter, when a comet gets this close to the Sun, the heat melts the ice within the Nuclei and causes a glowing head to form, known as the coma, and because the ice of the nuclei are composed of many different molecules some of these molecules escape the nuclei’s gravitational force easily causing a “Hydrogen Envelope” or “Hydrogen Cloud”. Most comets usually have two tails, and usually one is much brighter than the other. The tails form as a result of the sun’s solar wind – the stream of charged particles that emanate from the sun. The Solar Wind causes parts of the comet to become separated causing a narrow trail. This is how comets lose most of their mass and ice. Whilst in the orbit of the sun the comet speeds up as the strength of gravity is increased as it’s closer to the source.

As you can see the further away from the Sun a planet is the longer it takes to orbit, and the further out the planet is from the sun the colder it is as the heat radiation from the Sun isn’t as strong. The force holding these planets in orbit is gravity, as regularly everything would move in a straight line, unless there is another force acting upon it. In this case gravity, and the force acting upon towards the centre of a circle is called centripetal force. This force causes the round orbit pattern of our Solar System and many others. Other things are also influenced by centripetal force, meteors, dust and comets. As you can see the further away from the Sun a planet is the longer it takes to orbit, and the further out the planet is from the sun the colder it is as the heat radiation from the Sun isn’t as strong. The force holding these planets in orbit is gravity, as regularly everything would move in a straight line, unless there is another force acting upon it.

In this case gravity, and the force acting upon towards the centre of a circle is called centripetal force. This force causes the round orbit pattern of our Solar System and many others. Other things are also influenced by centripetal force, meteors, dust and comets. Although Pluto used to be classified a planet in August 2006 it became classified by several Scientists as a dwarf planet due to many moons within our Solar System being the same size or larger, stripping it of its planetary status, now just being a “dwarf planet” Although Pluto used to be classified a planet in August 2006 it became classified by several Scientists as a dwarf planet due to many moons within our Solar System being the same size or larger, stripping it of its planetary status, now just being a “dwarf planet” Our Solar system consists of The Sun, the central gravitational force due to its mass, 8 planets and a dwarf planet.

With this in mind, space travel seems daunting, especially with the extremities of space. Firstly scientists had to overcome the difficulties of the conditions in space, In space it is either hot or cold, hot being in the presence of the Sun’s infrared radiation and cold being hidden by another object. Several other problems in space include the lack of atmosphere, lack of gravity and the abundance of cosmic radiation. The radiation is something scientists haven’t been able to solve and it can limit the amount of time an astronaut should be on a mission, as it can damage their health causing cancers. However the other problems have been solved using various equipment, the lack of gravity whilst is makes movement easier it can weaken bones the longer an astronaut is out in space. While the lack of atmosphere would obviously kill anyone as there isn’t any oxygen, these two problems have been solved by use of exercise equipment which slows the process of bones weakening, while they create an atmosphere inside the spacecraft.

However not all space travelled has to be manned, most aren’t such as probes and satellites as it means human life isn’t at risk, but it also means that the spacecraft if it breaks down can completely jeopardize a mission or the mission can be lost if it goes out of orbit. Probes sent back information on the planets magnetic field strength, temperature, radiation, gravitational field strength and the composition of the atmosphere.

Even with these technological advances, it is still difficult to travel through space as it takes a long time and is expensive.

With this in mind, space travel seems daunting, especially with the extremities of space. Firstly scientists had to overcome the difficulties of the conditions in space, In space it is either hot or cold, hot being in the presence of the Sun’s infrared radiation and cold being hidden by another object. Several other problems in space include the lack of atmosphere, lack of gravity and the abundance of cosmic radiation. The radiation is something scientists haven’t been able to solve and it can limit the amount of time an astronaut should be on a mission, as it can damage their health causing cancers. However the other problems have been solved using various equipment, the lack of gravity whilst is makes movement easier it can weaken bones the longer an astronaut is out in space. While the lack of atmosphere would obviously kill anyone as there isn’t any oxygen, these two problems have been solved by use of exercise equipment which slows the process of bones weakening, while they create an atmosphere inside the spacecraft.

However not all space travelled has to be manned, most aren’t such as probes and satellites as it means human life isn’t at risk, but it also means that the spacecraft if it breaks down can completely jeopardize a mission or the mission can be lost if it goes out of orbit. Probes sent back information on the planets magnetic field strength, temperature, radiation, gravitational field strength and the composition of the atmosphere.

Even with these technological advances, it is still difficult to travel through space as it takes a long time and is expensive.

Space Travel
Space is enormous, the sheer size makes it difficult to measure in the normal metre or kilometre, and so new units have been developed depending on the scale. Within a solar system, the general unit is an Astronomical Unit (A.U), an A.U is the average distance between the Earth and Sun. But for most distances outside a solar system, generally galaxies and stars the unit used is the parsec (pc),a parsec is approximately 3.26 Light years and 1pc is also 206265 A.U. However although space is huge, closer objects are measured in kilometres or the diameter of a comet is measured in kilometre, and other objects may even be measured in comparison to others, although there are many units the most common is the parsec. Space is enormous, the sheer size makes it difficult to measure in the normal metre or kilometre, and so new units have been developed depending on the scale.

Within a solar system, the general unit is an Astronomical Unit (A.U), an A.U is the average distance between the Earth and Sun. But for most distances outside a solar system, generally galaxies and stars the unit used is the parsec (pc),a parsec is approximately 3.26 Light years and 1pc is also 206265 A.U. However although space is huge, closer objects are measured in kilometres or the diameter of a comet is measured in kilometre, and other objects may even be measured in comparison to others, although there are many units the most common is the parsec. Space suit designed to help Astronauts survive without the surrounding atmosphere Space suit designed to help Astronauts survive without the surrounding atmosphere Spirit

(A space probe by NASA)

However although small impacts may be predicted more frequently than we think, the probabilities are low that it will cause much damage. The image above is an extract of future predicted asteroid impacts on Earth, taken from the NASA website. Although there are predictions, they are extremely spaced out and can range from a 20 year span of the event happening, to a 50 year gap. Most of these impacts are predicted 0 on the Torino scale, which is a 10 point-scale, 0 means that it will have nearly no consequence while 1 merits careful monitoring and if it keeps rising more concern is warranted. However although small impacts may be predicted more frequently than we think, the probabilities are low that it will cause much damage. The image above is an extract of future predicted asteroid impacts on Earth, taken from the NASA website. Although there are predictions, they are extremely spaced out and can range from a 20 year span of the event happening, to a 50 year gap. Most of these impacts are predicted 0 on the Torino scale, which is a 10 point-scale, 0 means that it will have nearly no consequence while 1 merits careful monitoring and if it keeps rising more concern is warranted.

An Asteroid is defined as a small planetary body that orbits the sun, and depending on the size and stage of development they can also be classed into planetoids. Asteroids unlike comets are metal and rock based and are said to have formed closer to the sun, hence the lack of ice. Whilst a meteoroid is a particle that broke off a much larger asteroid or comet. When a comet or asteroid orbits near our planet, it can cause meteor showers, which are small particles being dissolved in our atmosphere due to the heat and speed. The majority of the reason the Asteroid belt, a huge group of asteroids between Mars and Jupiter, haven’t formed their own planet due to their own gravitational force is because of Jupiter’s An Asteroid is defined as a small planetary body that orbits the sun, and depending on the size and stage of development they can also be classed into planetoids. Asteroids unlike comets are metal and rock based and are said to have formed closer to the sun, hence the lack of ice. Whilst a meteoroid is a particle that broke off a much larger asteroid or comet.

When a comet or asteroid orbits near our planet, it can cause meteor showers, which are small particles being dissolved in our atmosphere due to the heat and speed. The majority of the reason the Asteroid belt, a huge group of asteroids between Mars and Jupiter, haven’t formed their own planet due to their own gravitational force is because of Jupiter’s Our Planet has been under siege by asteroids and meteoroids since the Earth was formed, early evidence of this includes approximately 65 million years ago when dinosaurs were around, a collision in the Chixulub Basin in Mexico caused the conditions on Earth to change to a point where it was uninhabitable for most organisms at the time.

The force of the asteroid was billions of times more powerful than the Hiroshima bomb, but the clouds of ash it formed caused an ice age as it blocked out the sun’s rays shrouding the Earth in complete darkness. Our Planet has been under siege by asteroids and meteoroids since the Earth was formed, early evidence of this includes approximately 65 million years ago when dinosaurs were around, a collision in the Chixulub Basin in Mexico caused the conditions on Earth to change to a point where it was uninhabitable for most organisms at the time. The force of the asteroid was billions of times more powerful than the Hiroshima bomb, but the clouds of ash it formed caused an ice age as it blocked out the sun’s rays shrouding the Earth in complete darkness. Asteroid, Meteroids and Meteors

Asteroid, Meteroids and Meteors even stronger gravitational force, as an object’s gravitational force is determined by something’s mass. However, when an asteroid becomes too large or starts the differentiation process it is classed as a planetoid, similar to that of Vesta. Vesta is a planetoid 530 km across (on average) whilst a normal asteroid is around 100km across and another great difference is the differentiation which makes it more like Earth and other planets. Differentiation is the process where the more dense rocks and minerals within a planetary body go to the middle whilst the less dense lighter substances float to the outer layers of the planet. This means Vesta may have a core, mantle and crust similar to that of Earth’s.

Even stronger gravitational force, as an object’s gravitational force is determined by something’s mass. However, when an asteroid becomes too large or starts the differentiation process it is classed as a planetoid, similar to that of Vesta. Vesta is a planetoid 530 km across (on average) whilst a normal asteroid is around 100km across and another great difference is the differentiation which makes it more like Earth and other planets. Differentiation is the process where the more dense rocks and minerals within a planetary body go to the middle whilst the less dense lighter substances float to the outer layers of the planet. This means Vesta may have a core, mantle and crust similar to that of Earth’s.

Life cycle of Stars

Stars are born in nebulae, a nebulae is a cloud of hydrogen gas in the air and dust in space, when a nebulae collapses due to the gravitational force, it forms protostars, the foetus equivalent of a star. Then the star expands as it runs out of hydrogen gas to burn, a red giant is formed in these later stages, although depending on the size of the original star it can also be a super-giant red giant. The expansion is due to the lack of hydrogen, causing the star, as it ages, to become dimmer and cooler.

After the formation of a red giant the star then turns into a red-dwarf which is even dimmer than a red giant. Red Dwarfs are very cool faint stars than are approximately 1/10 the diameter of the sun.

A smaller star after this would then turn into a white dwarf; a white dwarf is a small extremely hot star which has only 1% the luminosity of our sun due to its mass having been reduced significantly. A small star would then turn into a black dwarf.

Whilst a medium/ large star would expand until it exploded into a super nova. A super nova is the explosive death of a star that results in having the brightness of 100 million suns for a short period of time, these can occur when the gas from another star lands on a white dwarf causing it to explode destructively or within a star 10x the size of our sun, when it occurs in a star of this size it is caused by the nuclear reactions within the star.

Lastly after this a medium sized star would turn into a neutron star whilst a large star would turn into a black hole. A neutron star is composed mainly of neutrons and is produced during a supernova, which causes the protons and electrons to combine creating a neutron star. Neutron stars are extremely dense, normally having a mass three times of the Sun’s with only a 20km diameter, if the star is more dense than this it will collapse into itself creating a black hole.

A black hole is formed from super-massive stars at the end of their life span, a black hole will pull anything into its gravitational force even light, the density of a black hole is said to be immeasurable or even infinite. Stars are born in nebulae, a nebulae is a cloud of hydrogen gas in the air and dust in space, when a nebulae collapses due to the gravitational force, it forms protostars, the foetus equivalent of a star. Then the star expands as it runs out of hydrogen gas to burn, a red giant is formed in these later stages, although depending on the size of the original star it can also be a super-giant red giant. The expansion is due to the lack of hydrogen, causing the star, as it ages, to become dimmer and cooler.

After the formation of a red giant the star then turns into a red-dwarf which is even dimmer than a red giant. Red Dwarfs are very cool faint stars than are approximately 1/10 the diameter of the sun.

A smaller star after this would then turn into a white dwarf; a white dwarf is a small extremely hot star which has only 1% the luminosity of our sun due to its mass having been reduced significantly. A small star would then turn into a black dwarf.

Whilst a medium/ large star would expand until it exploded into a super nova. A super nova is the explosive death of a star that results in having the brightness of 100 million suns for a short period of time, these can occur when the gas from another star lands on a white dwarf causing it to explode destructively or within a star 10x the size of our sun, when it occurs in a star of this size it is caused by the nuclear reactions within the star.

Lastly after this a medium sized star would turn into a neutron star whilst a large star would turn into a black hole. A neutron star is composed mainly of neutrons and is produced during a supernova, which causes the protons and electrons to combine creating a neutron star. Neutron stars are extremely dense, normally having a mass three times of the Sun’s with only a 20km diameter, if the star is more dense than this it will collapse into itself creating a black hole.

A black hole is formed from super-massive stars at the end of their life span, a black hole will pull anything into its gravitational force even light, the density of a black hole is said to be immeasurable or even infinite.

The Big Bang Theory, The link with Galaxies, red shift and blue shift. The Big Bang Theory, The link with Galaxies, red shift and blue shift. The Doppler Effect is another piece of proof, not only for the Big Bang theory but part of the legitimacy of “Hubble’s Law”. The Doppler Effect was discovered by Christian Doppler in 1842, the Doppler Effect is something that occurs when light or sound is travelling away or towards a person.

For example when an ambulance zooms towards you the sound is gradually getting higher and higher pitched, but once it is past you again is starts getting lower, this is due to the frequency of the waves, a lower frequency means the sound is lower whilst a high frequency means a high pitch. The same applies with light, although instead of a change of pitch being perceived, there is a change in colour, thus the Red and Blue shifts. The Red shift occurs when an object is moving further away, this is because red light has a much lower frequency than blue light, meaning that when the frequency is high, or the light is moving towards the eyes, the Blue shift occurs. This Doppler effect then means that one can measure distances in a galaxy, or judge whether something is moving towards or away from the Earth.

The Doppler Effect is another piece of proof, not only for the Big Bang theory but part of the legitimacy of “Hubble’s Law”. The Doppler Effect was discovered by Christian Doppler in 1842, the Doppler Effect is something that occurs when light or sound is travelling away or towards a person. For example when an ambulance zooms towards you the sound is gradually getting higher and higher pitched, but once it is past you again is starts getting lower, this is due to the frequency of the waves, a lower frequency means the sound is lower whilst a high frequency means a high pitch. The same applies with light, although instead of a change of pitch being perceived, there is a change in colour, thus the Red and Blue shifts. The Red shift occurs when an object is moving further away, this is because red light has a much lower frequency than blue light, meaning that when the frequency is high, or the light is moving towards the eyes, the Blue shift occurs. This Doppler effect then means that one can measure distances in a galaxy, or judge whether something is moving towards or away from the Earth.

Edwin Hubble
The key link between the Big Bang theory and galaxies are that galaxies are one of the few pieces of evidence that the Big Bang theory is in fact true. Edwin Hubble proved the big bang theory through “Hubble’s Law”, “Hubble’s Law” says that all galaxies are moving away from each other and that a galaxy further away will move at a faster speed. The fact that galaxies are moving further away from each other prove that the universe is expanding, an analogy of this is a poppy-seed muffin, as the muffin expands the poppy-seeds get further apart. This effect is similar to that of the galaxy expanding. The key link between the Big Bang theory and galaxies are that galaxies are one of the few pieces of evidence that the Big Bang theory is in fact true. Edwin Hubble proved the big bang theory through “Hubble’s Law”, “Hubble’s Law” says that all galaxies are moving away from each other and that a galaxy further away will move at a faster speed. The fact that galaxies are moving further away from each other prove that the universe is expanding, an analogy of this is a poppy-seed muffin, as the muffin expands the poppy-seeds get further apart. This effect is similar to that of the galaxy expanding.

The Big Bang theory explains the existence of the universe, although the theory isn’t 100% proven or accurate it is the closest theory there is about the universe’s existence. The standard the form of the big bang theory says that the universe was formed about 13.7 billion years ago from a “singularity”, a singularity is a zone that defies physics as we know today and is thought to be in the core of a black hole, within a singularity the gravity is so intense that it turns a finite amount of matter into an infinite density, hence defying physics. The universe is said to have begun as an infinitely hot, infinitely dense matter and after its first appearance it inflated (The Big Bang) and from being infinitely hot and turned into our universe today.

This expansion is said to have still not stopped today meaning that the universe is still growing. The Big Bang theory explains the existence of the universe, although the theory isn’t 100% proven or accurate it is the closest theory there is about the universe’s existence. The standard the form of the big bang theory says that the universe was formed about 13.7 billion years ago from a “singularity”, a singularity is a zone that defies physics as we know today and is thought to be in the core of a black hole, within a singularity the gravity is so intense that it turns a finite amount of matter into an infinite density, hence defying physics. The universe is said to have begun as an infinitely hot, infinitely dense matter and after its first appearance it inflated (The Big Bang) and from being infinitely hot and turned into our universe today. This expansion is said to have still not stopped today meaning that the universe is still growing.

References:

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* http://www.atlasoftheuniverse.com/galaxy.html
* http://www.collinsonlinelearning.co.uk/Book/6a667711-e87b-41e3-a378-389434c938a5 * http://www.astro.wisc.edu/~dolan/constellations/extra/nearest.html * http://science.nasa.gov/astrophysics/focus-areas/what-are-galaxies/ * http://curiosity.discovery.com/question/what-are-galaxies * http://cas.sdss.org/dr5/en/proj/advanced/galaxies/tuningfork.asp * http://cas.sdss.org/dr5/en/proj/basic/galaxies/spirals.asp * http://www.astronomynotes.com/galaxy/s3.htm

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* http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/living_future/6_solar_system1.shtml * http://www.collinsonlinelearning.co.uk/Book/6a667711-e87b-41e3-a378-389434c938a5 * http://www.enchantedlearning.com/subjects/astronomy/comets/weblinks.shtml * http://burro.cwru.edu/stu/comets.html

* http://physicsquest.homestead.com/quest10.html
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* http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980226c.html * http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/living_future/6_solar_system3.shtml * http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/living_future/6_solar_system5.shtml Page__:

* http://www.bbc.co.uk/science/space/solarsystem/other_solar_system_bodies/asteroid * http://www.reuters.com/article/2010/03/04/us-dinosaurs-asteroid-idUSTRE6233YW20100304 * http://www.collinsonlinelearning.co.uk/Book/6a667711-e87b-41e3-a378-389434c938a5 * http://neo.jpl.nasa.gov/risk/

* http://www.universetoday.com/35615/what-is-an-asteroid/ * http://www.telegraph.co.uk/science/space/8190587/What-is-a-meteor.html * http://www.google.co.uk/search?q=Meteor+shower&oe=utf-8&rls=org.mozilla:en-GB:official&client=firefox-a&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=zs1AT6vXLOW_0QXRorWPDw&biw=1280&bih=852&sei=181AT9LeCIWe0QXH7MCPDw#um=1&hl=en&client=firefoxa&rls=org.mozilla:enGB:official&tbm=isch&q=meteor+shower+england&revid=1016110218&sa=X&ei=181AT6LVEsbP0QWguMiPDw&ved=0CEAQ1QIoAw&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=377317da35a80e4&biw=1280&
amp;bih=852 Page__:

* http://big-bang-theory.com/
* http://www.google.co.uk/imgres?q=The+Big+Bang+theory+diagram&um=1&hl=en&client=firefox-a&sa=N&rls=org.mozilla:en-GB:official&biw=1280&bih=852&tbm=isch&tbnid=L80NXdX-jvV4mM:&imgrefurl=http://www.fas.org/irp/imint/docs/rst/Sect20/A10.html&docid=FKPqEga7GIPhiM&imgurl=http://www.fas.org/irp/imint/docs/rst/Sect20/expanding.jpg&w=288&h=303&ei=Bp1CT9_pI4TG0QWCjZWPDw&zoom=1&iact=rc&dur=377&sig=112014988940938775133&page=1&tbnh=158&tbnw=150&start=0&ndsp=20&ved=0CHsQrQMwDg&tx=68&ty=95 * http://www.wisegeek.com/what-is-hubbles-law.htm

* http://www.wisegeek.com/what-is-the-doppler-effect.htm
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* http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/ *
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* http://www.atlasoftheuniverse.com/galaxy.html
* http://www.collinsonlinelearning.co.uk/Book/6a667711-e87b-41e3-a378-389434c938a5 * http://www.astro.wisc.edu/~dolan/constellations/extra/nearest.html * http://science.nasa.gov/astrophysics/focus-areas/what-are-galaxies/ * http://curiosity.discovery.com/question/what-are-galaxies * http://cas.sdss.org/dr5/en/proj/advanced/galaxies/tuningfork.asp * http://cas.sdss.org/dr5/en/proj/basic/galaxies/spirals.asp * http://www.astronomynotes.com/galaxy/s3.htm

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*
http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/living_future/6_solar_system1.shtml * http://www.collinsonlinelearning.co.uk/Book/6a667711-e87b-41e3-a378-389434c938a5 * http://www.enchantedlearning.com/subjects/astronomy/comets/weblinks.shtml * http://burro.cwru.edu/stu/comets.html

* http://physicsquest.homestead.com/quest10.html
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* http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980226c.html * http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/living_future/6_solar_system3.shtml * http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/living_future/6_solar_system5.shtml Page__:

* http://www.bbc.co.uk/science/space/solarsystem/other_solar_system_bodies/asteroid * http://www.reuters.com/article/2010/03/04/us-dinosaurs-asteroid-idUSTRE6233YW20100304 * http://www.collinsonlinelearning.co.uk/Book/6a667711-e87b-41e3-a378-389434c938a5 * http://neo.jpl.nasa.gov/risk/

* http://www.universetoday.com/35615/what-is-an-asteroid/ * http://www.telegraph.co.uk/science/space/8190587/What-is-a-meteor.html * http://www.google.co.uk/search?q=Meteor+shower&oe=utf-8&rls=org.mozilla:en-GB:official&client=firefox-a&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=zs1AT6vXLOW_0QXRorWPDw&biw=1280&bih=852&sei=181AT9LeCIWe0QXH7MCPDw#um=1&hl=en&client=firefoxa&rls=org.mozilla:enGB:official&tbm=isch&q=meteor+shower+england&revid=1016110218&sa=X&ei=181AT6LVEsbP0QWguMiPDw&ved=0CEAQ1QIoAw&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=377317da35a80e4&biw=1280&bih=852 Page__:

* http://big-bang-theory.com/