Chapter 3 Time and Matter There are three ingredients that make up the universe Space discussed in previous lecture Time mostly discussed in previous lecture o Our 7 day week is based on a superstition from the Babylonians They noticed that a few points of light in the sky moved differently from the other stars They saw 7 that could move this way which included the sun the moon and five planets Our 7 day week and their origins break down as follows Sunday named by the sun Monday named by the moon Tuesday named by Mars Tiu Wednesday named by Mercury Woden Thursday named by Jupiter Thor Friday named by Venus Freya Saturday named by Saturn o The month was determined by the time it takes the moon to complete a cycle of phases The time from one full moon to the next full moon is 29 days 12 hours 44 minutes and 2 9 seconds o The year was determined by how long it takes the Earth to revolve around the sun This takes about 365 days Also every 4 years we have a leap year due to this day being added each year o Platonic year How long it takes for the Earth to complete a wobble on its axis approximately 25 800 years After a platonic year is complete the north star changes o A kilogram weighs 2 2 pounds on Earth o Weight and mass are not the same Weight How strong gravity pulls on an object Mass The atoms that make up an object o The slug the fundamental English unit for mass A slug weighs 32 3 pounds on Earth Matter Chapter 4 The Earth o The Earth s equator is about 25 000 miles around and divides the Earth into northern and southern hemispheres o Lines of latitude north south o Lines of longitude east west o The North Pole is 90 while the South Pole is 90 Kent s coordinates are 41 N 81 W o 0 longitude runs through Greenwich England The Earth s layers divided into three sections o The outermost is the crust a 20 mile thick layer of light rocks o The next layer is the mantle which is 1800 miles thick of heavy rocks o The innermost layer or the core has two layers The outer core is 1300 miles thick and consists of molten The inner core is 800 miles thick with solid materials The Earth s atmosphere divided into three sections o Troposphere closest to our planet Extends upwards for 7 miles and contains most of our air and is where our weather occurs o Stratosphere Extends 7 to 45 miles upwards Very cold Air too thin to support life o Ionosphere Extends 45 to 200 miles upwards Reflects radio waves o Air composition 78 nitrogen 21 oxygen and 1 Carbon Dioxide