Astronomy - Chapter 3 The Universal Context of Life 3.1 The...

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Chapter 3 – The Universal Context of Life 3.1 – The Universe and Life The Universe is VAST and OLD The elements of life are widespread The same physical laws that operate on Earth operate throughout the universe 3.2 – The Structure, Scale, and History of the Universe Solar System – consists of the sun and all the objects that orbit it Milky Way Galaxy – (Galaxy) – is a great island of stars in space, containing from a few hundred million to a trillion or more stars. Milky Way contains more than 100 billion stars, orbits the galactic centre 230 million years Universe – The sum total of all matter and energy in existence Light Years – 1 light year is the distance that light can travel in 1 year, which is about 10 trillion kilometers. Dark Matter – Matter that we infer to exist from its gravitational effects but from which we have not detected any light; dark matter apparently dominates the total mass of the universe Dark Energy – name sometimes given to energy that could be causing the expansion of the universe to accelerate Universe is EXPANDING – Edwin Hubble discovered that average galaxy distance is increasing with time, therefore galaxies were once closer together Big Bang – The name given to the event thought to mark the birth of the universe, Big Bang Theory the scientific theory of the universe’s earliest moments, stating that all matter in our universe came into being at a single moment in time as an extremely hot, dense mixture of subatomic particles and radiation, measurements estimated that big bang occurred about 14 billion years ago… (universe is 13.7 billion years old) – Georges Lemaitre o 2 evidence to support this, 1st – radiation from big bang left a cosmic microwave background o 2 nd – calculations of chemical prediction that big bang began with ¾ hydrogen and ¼ helium, which is consistent with the composition of the universe Nuclear Fusion – a star is born when gravity compresses the material in a cloud to the point where the center becomes dense enough and hot enough to generate energy by nuclear fusion A stars energy is from the fusion of 4 Hydrogen nuclei making 1 helium nucleus and releases energy, this is the current power source in stars/sun, from their Hydrogen cores
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Demonstrated by Einstein’s E = mc 2 (lost mass is converted to energy) Bigger sun = burns at a much faster rate, = faster death Smaller sun = burns slower therefore, longer life Stars die by titanic explosions called supernovae The floating matter mixes with other matter in the galaxy and thus can recreate and generate new stars, thus function as a cosmic recycling plant Creation of elements: o If beginning matter was hydrogen/helium, and then 3 helium can make 1 carbon through fusion, most of this occurs in very dense and hot locations like the sun, other elements are formed and then dispersed when a star dies… o Evidence for this hypothesis
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This note was uploaded on 02/12/2010 for the course ASTRO 121 taught by Professor Brown during the Spring '08 term at UWO.

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Astronomy - Chapter 3 The Universal Context of Life 3.1 The...

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