Lecture 2 - Exploring the Heavens

Lecture 2- - Exploring the Heavens ASTRONOMY 3 Lesson 2 1 Star Trails above Mauna Kea see http/antwrp.gsfc.nasa.gov/apod/ap051220.html NATURE of

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Unformatted text preview: Exploring the Heavens ASTRONOMY 3 Lesson 2 1 Star Trails above Mauna Kea - see http://antwrp.gsfc.nasa.gov/apod/ap051220.html NATURE of the Universe Review of Lesson 1 Astronomy - Exploring the Heavens • Location of Sunrise and Sunset on the horizon changes with season • Constellations are different in different cultures. They help people to orient themselves on the sky and to use them for navigation. • Powers of 10: the observable Universe is vast, 10 19 times larger than Earth, 10 26 times larger than a Human 2 • E.1 The “Obvious” View • E.2 Earth’s Orbital Motion • E.3 The Motion of the Moon • Summary & Homework NATURE of the Universe Today’s Topics Astronomy - Exploring the Heavens Lab 2 (starts this week): Planetarium and Sky Motions 3 NATURE of the Universe The “Obvious” View Astronomy - Exploring the Heavens Stars appear to be projected on the “celestial sphere”, while in reality each star might be at a different distance from Earth Constellations do not represent physical groups of stars! 4 The speed of light is 3*10 8 m/s. In a year light travels 1*10 16 m. This distance is called a lightyear. To cross the Milky Way, which is 10 21 m or 10 5 lightyears in diameter, light needs 10 5 yr. NATURE of the Universe The “Obvious” View Astronomy - Exploring the Heavens Mapping the skies- how to fnd your way among the stars? 5 Coordinates of the Math Sciences Building: longitude W 118° 26’ 35’’, latitude N 34° 4’ 11’’ NATURE of the Universe The “Obvious” View Astronomy - Exploring the Heavens Mapping the skies- how to fnd your way among the stars? On Earth, latitude and longitude are used identiFy a location on Earth (e.g. with the help oF GPS, the Global Positioning System) 5 Coordinates of the Math Sciences Building: longitude W 118° 26’ 35’’, latitude N 34° 4’ 11’’ NATURE of the Universe The “Obvious” View Astronomy - Exploring the Heavens Astronomers place a grid of coordinates across the celestial sphere to locate stars in a particular region of the sky. Mapping the skies- how to Fnd your way among the stars 6 NATURE of the Universe The “Obvious” View Astronomy - Exploring the Heavens We call these coordinates “Right Ascension ” and “Declination ” • Right ascension : measured in hours, minutes and seconds eastward from the position of the Sun at the spring equinox • Declination : degrees north (positive) or south (negative) of the celestial equator Examples: Polaris (Epoch J2000) RA = 2 h 31 m 49 s DEC= +89° 15’ 51’’ Rigel, β Orionis (J2000) RA = 5 h 14 m 32 s DEC= -8° 12’ 6’’ 7 On a sky chart with North facing up, East is always to the Left - this is opposite to a terrestrial map, where East is to the right. Imagine lying on your back watching the sky with your head facing north - east will then we to your left! NATURE of the Universe...
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This note was uploaded on 10/13/2008 for the course ASTR 3 taught by Professor Hauser during the Fall '07 term at UCLA.

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Lecture 2- - Exploring the Heavens ASTRONOMY 3 Lesson 2 1 Star Trails above Mauna Kea see http/antwrp.gsfc.nasa.gov/apod/ap051220.html NATURE of

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