Introduction to Astronomy_Holder_Date__031510

Introduction to Astronomy_Holder_Date__031510 - Solar...

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Solar system – our Sun and all the objects that orbit it Milky Way Galaxy – huge, disk-shaped collection of stars Galaxy – great island of stars in space, with a few hundred million to a trillion stars Star - a large, glowing ball of gas that generates heat and light through nuclear fusion Planet – moderately large object that orbits a star; it shines by reflected light. Plants may be rocky, icy, or gaseous in composition. Moon – an object that orbits a planet Asteroid – a relatively small and rocky object that orbits a star Comet - a relatively small and icy object that orbits a star (2 tails) Only show their tails when they are close to the sun Solar (Star) System – A star and all the material that orbits it, including its planets Galaxy – a great island of stars in space, all held together by gravity and orbiting a common center (we have 100 billion stars)
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Universe – the sum total of all matter and energy; that is, everything within and between all galaxies Earth -> Solar System -> Milky Way Galaxy -> Local Group -> Local Supercluster -> The Universe We are in the local group, 40 galaxies 2 big galaxies, Andromeda and another one. 38 other galaxies which are clustered together Andromeda (M31) is about 2.5 million light-years away Nuclear Fusion – the process in which lightweight atomic nuclei smash together and stick (or fuse) to make heavier nuclei. AU (astronomical unit) – the average distance between Earth and the Sun, which is about 150 million km. 1 AU is the length of the semimajor axis of Earth's orbit Light-Year – the distance that light can travel in a 1 year, which is about 10 trillions kilometers, which is 6 trillion miles – the distance that light can travel in a 1 year, which is about 9.46 trillions kilometers the speed of light is 300,000 km/s or. . distance = speed x time The farther away we look in distance, the further we look back in time Earth – created 4 ½ billion years ago. 2% of the original hydrogen and helium converted into heavier elements. We are all "star stuff" because we and our planets are made from elements in dead stars Observable Universe – the portion of the entire universe that we can potentially observe.
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1.2 The Scale of the Universe If model sun is the size of a grapefruit, then Jupiter is a marble, and the Earth is the ball of a pen Moon Rise/Set by Phase The different phases also rise and set at different times: Full moon – the moon is opposite the sun, so it rises at sunset, culminates at midnight, and sets at dawn New moon – the moon is on the same side as the sun, and so is only in the sky during the day (rises at dawn, sets at dusk) First quarter rises at noon, culminates at 6pm, and sets at midnight
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This note was uploaded on 08/30/2010 for the course PHYS 133 taught by Professor Staff during the Spring '08 term at University of Delaware.

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Introduction to Astronomy_Holder_Date__031510 - Solar...

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