DSST Astronomy notes 1

22 earths atmosphere is mostly nitrogen 78 nitrogen

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22) Earth’s atmosphere is mostly Nitrogen , 78% nitrogen, 21% oxygen, 1 % argon, traces of water, carbon dioxide and other gases 23) Magnetic Poles of the Earth a) Located 1200 miles from its geographical poles b) North magnetic pole is in Northeast Canada c) has a magnetic field similar to that produced by a bar magnet 24) Jean Foucault – in 1851 French physicist proved that the Earth rotates through the use of a pendulum 25) Coriolis Effect – is any apparent deflection in the motion of a body resulting from the Earth’s rotation a) Objects moving freely over the surface of the Earth are deflected a.i) To the right in the Northern Hemisphere a.ii) To the left in the Southern Hemisphere (a.ii.1) Can be seen in weather patterns affects the winds, most obliviously in large hurricanes 26) Equator – a circle on the surface of a sphere whose center is at the center of the sphere 27) Meridians –– circles intersect the equator at right angles an can be used to specify the east-west location of that place 28) Longitude – the number of degrees, minutes, and seconds of arc along the equator a) Longitude lines are vertical and measure how far a location is east or west of the Prime Meridian a.i) Prime Meridian – passes through Greenwich, England, site of the Royal Observatory 29) Latitude – is the number of degrees, minutes and seconds of arc measured along its meridian starting at the equator a) Measured either north or south of the equator from 0 degrees to 90 degrees b) Latitude lines are horizontal, and measure north or south of the equator 30) Celestial Sphere –thought to be hollow shell of extremely large radius centered on the observer a) Stays still, its earth rotates 31) Zenith – is the point on the celestial sphere that directly over our heads at any given time a) Used to denote positions of objects in the sky 32) Horizon – passed through the center of the Earth and is parallel to the sensible horizon of a given position or plane of such a circle a) Zenith and horizon are relative to where on Earth you are 33) Horizontal Coordinate System – uses measurements relative to the observers horizon a) Consists of two measurements a.i) Azimuth – runs 0-360 degrees and tells the observer what direction to look a.ii) Altitude – tells the observer how to look 34) Obliquity of the Ecliptic Plane – is the imaginary plane defined by the projection of Earth’s orbit onto the celestial sphere a) Plane in which the Earth revolves is 23.5 degrees different that the plane of the equator called Obliquity of the ecliptic b) Obliquity of the ecliptic that causes the variance in the seasons on Earth 35) Seasons of Earth – result because the plane in which the Earth revolves does not coincide with the plane of the Earths equator a) Earth’s axis is tilted from the vertical by 23.5 degrees as it orbits around the sun b) The Northern Hemisphere is inclined toward the sun in June and away from the sun in December 36) Earth orbits about 91.5 million miles to 94.5 million miles from the sun 37) Measure of time – based on the rotation of the Earth
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a) Each day is divided into 24 equal parts called hours
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22 Earths atmosphere is mostly Nitrogen 78 nitrogen 21...

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