DSST Astronomy notes 1

# Each day is divided into 24 equal parts called hours

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Each day is divided into 24 equal parts called hours 38) Solar Day – one complete rotation of the Earth a) 365 days in a year, the time is takes to make one complete revolution around the sun and 360 degrees in a circle a.i) Therefore daily motion of the earth in its orbit is about 1 degree 39) Day – natural units of the calendar are the day, based on the period of rotation of the Earth 40) Month – is based on the period of revolutions of the moon around the Earth a) 27 and 1/3 days 41) Year – based on the period of revolution of the Earth around the sun a) 365 days, 6 hours, 9 minutes and 10 seconds a.i) The 6 hours extra in our orbit account for the leap year every four years 42) Units of calendar measure day, month, year – they do not divide evenly into each other 43) Week – an independent unit invented by man a) Seven days of the week are named for the seven planets including the sun and moon 44) Time Zones – came with the development of the railroads and telegraphs a) US has four time zones a.i) EST – Eastern a.ii) CST - Central a.iii) MST - Mountain a.iv) PST – Pacific b) There are 24 international times zones around the world (decided in Washington, DC in 1884 45) Speed of Light = 186,282.397 miles per second a) Highest possible speed and is universally observed a.i) One of the Theory’s of Relativity 46) Normal – is a term used when discussing the laws of optics an visible light a) Simply a line or direction perpendicular to that surface at that point 47) Law of Reflection – describes the manner in which light is reflected from a smooth or shiny surface a) Law states that the angle of reflection is equal to the angle of incidence, and that the reflected lies in the plane formed by the normal and the incident ray (all three must line up) 48) Law of Refraction – deals with the deflection of light when it passes from one kind of transparent medium into another 49) Dispersion of light – is the manner in which white light, which is a mixture of all wavelengths of visible light can be decomposed into its constituent wavelength or colors when it passes from one medium into another 50) Moon is Earths closest celestial neighbor and only natural satellite with accompanies the Earth in its annual revolution around the sun a) Moon shines only by reflected sunlight, and is the second most brilliant object in the sky 51) Distance from center of the moon to the center of the Earth is 238,857 miles 52) Moon is covered with craters of varying shapes and sizes a) Known as seas – assumed early on to be large bodies of water 53) Eclipses – when the moon’s shadow strikes the earth 54) Solar Eclipse – people on Earth within that shadow see the sun covered by the moon 55) Lunar Eclipse – people on the night side of the Earth see the moon darker 56) Solar System – consists of the sun and a large number of smaller objects gravitationally associated with it a) 99.9 % of the matter is the sun b) .135 planets

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c) .00004 Satellites d) .00003 comets e) .0000003 Minor Planets f) .0000003 Meteoroids g) .0000001 Interplanetary Medium
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Each day is divided into 24 equal parts called hours 38...

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