Chapter Two

Chapter Two - Chapter Two Positional astronomy study of the...

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Chapter Two Positional astronomy – study of the positions of objects in the sky and how these positions change Constellations – groupings of stars (88 total) diurnal motion – any apparent motion in the sky that repeats on a daily basis, such as the rising and setting of the stars celestial sphere – an imaginary sphere of very large radius centered on an observer; the apparent sphere of the sky celestial equator – a great circle on the celestial sphere 90 degrees from the celestial poles celestial poles – the points about which the celestial sphere appears to rotate North celestial pole & south celestial pole – where earth’s axis of rotation intersects the celestial sphere Zenith – point in the sky directly overhead an observer Circumpolar – stars sufficiently near the north celestial pole revolve around the pole, never rising or setting Seasons occur because the Earth’s axis of rotation is not perpendicular to the plane of its orbit. Tilted at 23.5 degrees away from perpendicular SUMMER: sun is high and its rays are more concentrated on a smaller area so the heat is more intense WINTER: sun is lower in the sky so rays are spread out more which decreases its intensity seasons are NOT based on distance to the sun for the Earth’s orbit is fairly circular
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This note was uploaded on 09/29/2009 for the course ASTR 101 taught by Professor Christiansen during the Spring '08 term at UNC.

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Chapter Two - Chapter Two Positional astronomy study of the...

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