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Astronomy Astronomy is the study of all physical objects beyond Earth. 1. The Original Science The seasonal movement of celestial bodies, e.g. sun, moon and planets, has helped create our modern day calendar. Most calendars are made up of: a. Year – time required for the earth to orbit the sun b. Month – time required for the moon to orbit the earth c. Day – time required for the earth to rotate once on it’s axis Astronomy Earlier civilizations based their calendars on moon phases, planet alignments and sun positions. Julius Caesar created the Julian calendar, 365.25 days per year; created the leap year to help realign the seasons to the calendar Romans had the greatest affect on our modern calendar Later, it was discovered that the Julian calendar was wrong; so the Gregorian calendar was created, 365.242 days per year Astronomy Evidence from other countries that astronomy observations was used. a. Nabta, Egypt - the oldest known astronomical alignment of megaliths in the world b. Stonehenge , England – group of stones in a circle which correlate with summer and winter solstices Astronomy c. Babylonians – believed in astrology, a fuzzy science how the moon, stars and planets affect our lives d. Chinese – understood eclipses and mapped hundreds of stars e. Greeks - not so much in observation as it was in applying logical thinking and geometry to these observations Astronomy f. Mayan, S. America - were quite accomplished astronomers g. Arabs - was for the purpose of time-keeping, also for determination of latitude and longitude h. Romans - created our modern day calendar, with some revisions Astronomy Astronomers a. Ptolemy – 140 A.D. created the Ptolemaic System, which predicted the positions of the planets based on his earth-centered system Astronomy b. Copernicus – 1543 wrote Little Commentary, Copernicus's theory of a universe with the sun at its center. c. Tycho Brahe– 1546 observations were made using only a compass and an astrolabe; most accurate measurements of the sky ever made without a telescope. Astronomy d. Johannes Kepler – 1600’s discovering the three laws of planetary motion e. Galileo Galilee – 1600’s first person to use a telescope to observe the stars Astronomy f. Issac Newton -1600’s explained why the planets orbited the sun: a. centrifigal force b. gravity Astronomy A skater rotates around their imaginary vertical axis A log can rotate around its horizontal axis Earth rotates around on it’s imaginary axis through the North and South poles There is a 23.50 tilt to the earth Astronomy 2. Mapping the Stars Ancient civilizations linked stars into recognizable patterns; these patterns are called constellations Astronomers divide the regions of the sky into 88 constellations Northern Hemisphere Southern Hemisphere Astronomy There are three concepts that help you describe locations of stars a. altitude – angle between object and horizon b. zenith – 900 to the observer; straight up c. horizon – sky and earth meet The stars you see at night depend on a. your location b. time of year c. time of night Astronomy To plot positions of stars use: a. Declination - is like latitude north or south of equator b. Right ascension - is like longitude; uses 24 hours as divider east of point on equator, vernal equinox (days and nights the same) Spring Constellations in Northern Hemisphere Astronomy Astronomy Measuring in Space Astronomers use the light year to measure the distance between us and the stars or planets Astronomy Some interesting Facts on Distance In one second, a beam of light can travel: Seven Times around the Earth. From Earth to the Moon 1.25 seconds From Earth to the Sun 8.3 minutes From the Sun to Neptune the furthest of the Sun's major planets 4.2 hours Astronomy The rotation of the earth causes what we call night and day. This occurs every 24 hours. Astronomy Day and Night Astronomy While the earth rotates around it’s axis, the earth is also revolving around the sun. One revolution or orbit around the sun takes about 365 days or one year. Astronomy Seasons on Earth There are four seasons on Earth; spring,, summer, fall, winter Why? Because of the 23.50 from vertical tilt of the earth! Astronomy The Seasons Astronomy Remember, the seasons are not affected by the Earth’s distance from the sun. Actually, during summer the Earth is furthest away from the sun!!!!! Let’s take a look at summer in northern hemisphere a. north is towards the sun b. more hours of daylight c. winter in southern hemisphere Astronomy Let’s take a look at winter in northern hemisphere a. north is away from the sun b. less hours of daylight c. summer in southern hemisphere Just two days a year, the noon sun is pointing north or south. This is called solstice. 1. December 21, 23.50 south winter in northern hemisphereWinter solstice shortest day of the year 2. June 21, 23.50 north summer in northern hemisphere longest day of the year Summer solstice Astronomy On just two days a year, the noon sun is pointing at the equator. This is called equinox. 1. March 21, vernal equinox a. marks the beginning of spring b. daytime and nighttime are the same c. day gets longer 2. September 23, a. marks the beginning of fall b. daytime andautumnal nighttimeequinox are the same c. days get shorter Astronomy Astronomy Astronomy Astronomy Astronomy Motions of the Moon Moon revolves around the earth every 27 days Moon rotates on it’s axis every 27 days Astronomy Phases of the Moon The moon goes through one set of phases every month. Astronomy Astronomy Astronomy Eclipses There are two types of eclipses 1. Solar eclipse 2. Lunar eclipse Astronomy Solar eclipse a. moon passes between Earth and the sun Two types of solar eclipse a. total solar - shadow is centered at a point on the earth this cone shaped shadow is called the umbra no part of the sun can be seen b. partial solar - shadow is outside the cone, this is called the penumbra part of the sun can be seen blue – penumbra black - umbra Astronomy Astronomy Total Solar Eclipse Partial Solar Eclipse Astronomy Lunar Eclipse a. Earth passes between moon and sun, only occurs during the full moon phase Two types of lunar eclipse a. total lunar – when the Earth, moon and sun are in direct alignment; you see Earth’s shadow on the moon b. partial lunar – when the Earth, moon and sun are not in direct alignment Astronomy Total lunar eclipse Astronomy Astronomy Tides a. occurs because of differences in how much the moon pulls on the Earth b. actually pulls the water off of Earth c. tides allow for animals to live in areas close to the oceans Astronomy image of no tides c. Two types of tides that occur daily low tide high tide high tide low tide Astronomy d. two types of tides that occur twice per month 1. spring tide a. springs off the earth b. only occurs at new moon phase c. Earth/moon/sun in line Astronomy 2. Neap tide a. first and last quarter moon phase b. moon is at right angle to earth/sun c. not much of a tide Astronomy Earth’s moon 1. Some information about the moon a. temperatures range from 1000 C to -1730 C b. 1/6th the gravity of Earth so if a man weighs 100 lbs. on Earth, he weighs 16 lbs on the moon c. moon has many craters and maria Astronomy Missions to the Moon a. July 1969 – Apollo 11, 1st landing on the moon Astronomy b. 1994 – Clementine, photographed the moon showed what type of minerals are on the moon Astronomy c. 1998 – Lunar Prospector, mapped the entire moon found there was water frozen at the poles of the moon Astronomy Comets chunks of ice and dust whose orbits are usually very long ellipses Comets are made up of two parts 1. head – made up of a. nucleus b. coma 2. tail – gas and dust Astronomy Asteroids Three main features: 1. objects revolving around the sun 2. too small to be called planets 3. between Jupiter and Mars Astronomy Meteors A meteoroid is a chunk of rock in space Two things can happen 1. if burns up in Earth’s atmosphere it is called a meteor 2. if it continues through atmosphere and hits Earth it is called a meteorite