# ASTR100 (Spring 2008) Prologue to Cosmology Finding the Universe

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The Cosmic Calendar: a scale on which we pack the historical backdrop of the universe into 1 year. ... The Cosmic Calendar: a scale on which we pack the historical backdrop of the ...

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﻿ASTR100 (Spring 2008) Introduction to Astronomy Discovering the Universe Prof. D.C. Richardson Sections 0101-0106

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How would we be able to know what the universe resembled previously? Light goes at a limited speed ( c = 300,000 km/s). In this way, we consider articles to be they were before: The more distant we're off look in separation, the further back we look in time.

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Example: This photograph demonstrates the Andromeda Galaxy as it looked around 2 ½ million years prior. Address: When will have the capacity to see what it would appear that now? M31, The Great Galaxy in Andromeda

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Definition: A light-year The separation light can go in one year. Around 10 trillion km (6 trillion miles). Distance = Speed x Time = (300,000 km/s) x (1 yr) x (31,557,600 s/yr) = 9,500,000,000,000 km! = 9.5 x 10 12 km

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At awesome separations, we consider articles to be they were the point at which the universe was much more youthful.

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Can we see the whole universe?

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Why wouldn't we be able to see a cosmic system 15 billion light-years away? (Accept the universe is 14 billion years of age) Because no cosmic systems exist at such an awesome separation. Universes may exist at that separation, however their light would be excessively black out for our telescopes, making it impossible to see. Since looking 15 billion light-years away means looking to a period before the universe existed.

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Why wouldn't we be able to see a cosmic system 15 billion light-years away? (Accept the universe is 14 billion years of age) Because no cosmic systems exist at such an incredible separation. Worlds may exist at that separation, however their light would be excessively black out for our telescopes, making it impossible to see. Since looking 15 billion light-years away means looking to a period before the universe existed.

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Milky Way shapes Oldest known life (single-celled) New Year's Day: The Big Bang Sun & planets frame First multi-cell living beings How do our lifetimes contrast with the age of the universe? The Cosmic Calendar: a scale on which we pack the historical backdrop of the universe into 1 year.

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How do our lifetimes contrast with the age of the universe? The Cosmic Calendar: a scale on which we pack the historical backdrop of the universe into 1 year.

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Spaceship Earth

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How is Earth Moving in Our Solar System? The Earth turns around its pivot once consistently.

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How is Earth Moving in Our Solar System? The Earth circles the Sun ( rotates ) once consistently.

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How is Earth Moving in Our Galaxy? The Sun moves arbitrarily in respect to other close-by stars, and circles the cosmic system once every 230 million years .

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More point by point investigation of the Milky Way's pivot uncovers one of the best secrets in space science… dull matter! The majority of Milky Way's light originates from circle and lump … . be that as it may, a large portion of the mass is in its radiance

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How do Galaxies Move Within the Universe? Cosmic systems are conveyed alongside the development of the universe.

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Part C The accompanying articulations depict courses in which the similarity may apply to the genuine universe. Which articulations are right? A. Both the raisin cake and the universe have an all around characterized inside and outside. B. Raisin 1 is close to the focal point of the cake, pretty much as our cosmic system is close to the focal point of the universe. C. The temperature begins low and finishes high in both the raisin cake and the universe. D. The raisins stay generally an indistinguishable size from the cake grows, pretty much as systems stay generally an indistinguishable size from the universe extends. E. The normal separation increments with time both between raisins in the cake and between cosmic systems in the universe. F¡. An onlooker at any raisin sees more far off raisins moving endlessly quicker, pretty much as an eyewitness in any cosmic system sees more removed worlds moving without end speedier. Enter the letters of every single right explanation in sequential order arrange (without spaces). For instance, if explanations C and E are right, enter CE. DEF Correct Like any logical model, the raisin cake similarity has impediments, however it gives us a decent general picture of how the universe is growing.

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Are we steadily sitting still? No! Earth pivots on hub: > 1,000 km/hr Earth circles Sun: > 100,000 km/hr Solar framework moves among stars: ~ 70,000 km/hr Milky Way turns: ~ 800,000 km/hr Milky Way moves in Local Group Universe extends

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Patterns in the Night Sky

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What are heavenly bodies? A heavenly body is an area of the sky. 88 groups of stars fill the whole sky (North & South).

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Thought Question The brightest stars in a heavenly body… all have a place with a similar star group. all lie at about a similar separation from Earth. may really be very far from each other.

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Thought Question The brightest stars in a group of stars… all have a place with a similar star bunch. all lie at about a similar separation from Earth. may really be very far from each other.

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The Celestial Sphere Stars at various separations all seem to lie on the divine circle. The ecliptic is the Sun's obvious way through the divine circle.

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The Celestial Sphere

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The Milky Way A band of light making a hover around the divine circle. What is it? Our view into the plane of our cosmic system.

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The Milky Way

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How would we find questions in the sky? A protest's height (above skyline) and bearing (along skyline) indicate its area in your neighborhood sky.

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We measure the sky in edges ... clear

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Angular Measurements Full circle = 360º 1º = 60  (arcminutes) 1  = 60  (arcseconds)

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Thought Question The rakish size of your finger at a careful distance is around 1  . What number of arcseconds is this? 60 arcseconds. 600 arcseconds. 60  60 = 3,600 arcseconds.

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Thought Question The rakish size of your finger at a careful distance is around 1  . What number of arcseconds is this? 60 arcseconds. 600 arcseconds. 60  60 = 3,600 arcseconds.

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Why do stars rise and set? Earth pivots west to east, so stars seem to hover from east to west.

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What moves? The Earth or the sky?

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Celestial Sphere Zenith : Point specifically overhead Horizon : Where the sky meets the ground

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Celestial Sphere North Celestial Pole : Point on divine circle above North Pole Celestial Equator: Line on heavenly circle above Equator

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Our view from Earth Stars close to the north heavenly post are circumpolar and never set. We can't see stars close to the south divine shaft. Every other star (and Sun, Moon, planets) ascend in east and set in west. A circumpolar star never sets Celestial equator This star never rises Your frame of reference

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Ended Here 1/31/08 (bunches of inquiries amid address, in addition to authoritative stuff)