Total Solar Eclipse Marshall Island 2009 Total Solar Eclipse Marshall Island 2009 Credit V Rusin Course Announcements Quiz 1 on Wednesday 31 August Hints today and in coming lectures You should be registered for Mastering Astronomy by now The first assignment is now past due Course ID LINDSAYA152F2016 Assignments Reading Assignments No new reading Parallel Lectures CC Astronomy Episodes 4 and 5 Watch by Monday 29 Aug Mastering Astronomy Chapter 1 Homework Due Wednesday 31 Aug at 11 59 PM EDT Quiz 1 Hints A few types of questions to expect 1 The time period that it takes to rotate exactly 360 about its rotation axis is known as A B C D E Solar Day Tropical Year Synodic Month Sidereal Day Nautical Day Possible Variants I ask what the noon to noon time period is I ask which is longer the Solar or Sidereal Day Quiz 1 Hints A few types of questions to expect 2 on the Celestial Sphere is analogous to latitude on Earth A B C D E North Celestial Pole South Celestial Pole Ecliptic Right Ascension Declination Possible variants I ask what is analogous to longitude I give the Celestial Coordinate and you give the Earth analog Motion of the Moon Earth Moon system to scale Orbital Period or Sidereal Period of the Moon is 27 3 days Again that means the amount of time to complete one 360 rotation Synodic Period or period for a full cycle of lunar phases is longer at 29 5 days Note Very close to 4 weeks 28 days New Moon to New Moon time or equivalently Full to Full Phases of the Moon Due to relative position of Sun Earth and Moon Quarter 3 Weeks Later Incoming Sunlight 4 Weeks Day 0 New 2 Weeks Later Full 1 Week Later Quarter Key Concepts 1 Moon is bright because of reflected sunlight 2 Half of the Moon is always illuminated 3 The phase we see is due to our view of the illuminated portion 4 Takes about 4 weeks to complete synodic period Moon Phases If you learn how to make the diagram to the right then you will be well on your way to Phases of the Moon mastery Advanced Skills Keeping track of Earth s rotation as well so you can understand rise set and meridian crossing times UNL Lunar Phase Simulat or Example Quiz Question A Today is a Third Quarter Moon Draw the Moon in the appropriate box and sketch what that Moon looks like as viewed from Earth in the double lined box to the right B What phase will the Moon be in one week from today Incoming Sunlight Sketch of TODAY s Moon Example Quiz Question A Today is a Third Quarter Moon Draw the Moon in the appropriate box and sketch what that Moon looks like as viewed from Earth in the double lined box to the right B Next week will be a New Moon Incoming Sunlight Sketch of TODAY s Moon Eclipses Due to the alignment of Sun Earth Moon Credit Alfredo Garcia Jr Credit Cat Wu S Lindsay Time lapse images of Total Solar Eclipse Total Lunar Eclipse Credit Geoff Sims Credit Forrest Egan Eclipses General Eclipses occur when the Sun Moon and Earth form a straight line Eclipses are caused by the shadow of the Earth Moon falling on the Moon Earth Note This does not always happen because the Moon s orbit is inclined by 5 2 Solar Eclipse Alignment Note the 5 20 inclination Lunar Eclipse Alignment A more true perspective 5 2 Degree Inclination Viewed Edge On Two points in front and behind where 0o between Sun Earth Line Maximum 5 20 extent above Sun Earth Line 5 2o Maximum 5 20 extent below Sun Earth Line For an eclipse to occur the angle between the Sun Earth Moon line is very near to 00 Lunar Eclipses Lunar Eclipses Earth is between Sun and Moon Lunar Eclipses only occur during a Full Moon Call it a partial eclipse when only partially shadowed Total eclipse when entirely shadowed completely in the umbra Motion of the Moon Solar Eclipses Moon is between Sun and Earth New Moon Partial when only partially shadowed in penumbra Total when entirely shadowed in umbra Partially shadowed Penumbra Completely shadowed Umbra Motion of the Moon Solar Eclipses Moon is between Sun and Earth Solar Eclipses only occur during a New Moon Umbra is very narrow always 270 km making the area a Solar Eclipse to be very limited and never last more than 7 5 minutes Path of Totality for August 21 2017 Solar Eclipse Solar Eclipses Only occur during New Moon Moon is between Sun and Earth New Moon Partial when only partially shadowed in penumbra Total when entirely shadowed in umbra Partial Eclipse when area is in the Penumbra Total Eclipse when area is in the Umbra Total Solar Eclipse During a total solar eclipse you can see the outer atmosphere of the Sun called the Corona TOP Total Solar Eclipse Marshall Island 2009 Credit V Rusin BOTTOM Total Solar Eclipse Svalbard April 2015 Credit M Druckm ller Solar Eclipses The Annular Eclipse Moon is too distant Moon s orbit is not perfectly round and therefore sometimes closer and sometimes farther away If in the umbra of a solar eclipse when Moon is further away the disk of the Moon is too small to entirely block the Sun and an Annular Eclipse occurs Annular eclipse May 20 2012 Quiz 1 Possible Questions 1 For a Total Solar Eclipse to occur the Moon must be in what phase New Moon For the Moon to cast it s shadow on the Earth it must be between the Sun and Earth 2 For a Total Lunar Eclipse to occur the Moon must be in what phase Full Moon For the Earth to cast it s shadow on the Moon it must be between the Sun and Moon Incoming Sunlight 4 Weeks Day 0 New 2 Weeks Later Full 1 Week Later Quarter Eclipse Seasons Eclipses don t occur every month because the Moon s orbit is inclined 5 2o with respect to Earth s orbital plane A 3D View of the Situation Node Node point in Moon s orbit where it crosses the Ecliptic Eclipse Seasons The precise alignment requirement for eclipses means that eclipses are favorable twice per year So called Eclipse Seasons Must be in this in this alignment Solar and Lunar eclipses occur in pairs Must have New Moon Or Full Moon at these orbital points Measuring Distances Simple Geometry and Trigonometry Distance Triangulation 90o Baseline Can calculate Distance to Object given that you have measured 1 the Baseline distance and 2 the angle You won t have to work out the geometry trigonometry but do know the method Angular Measurement In Astronomy things are very far away so angles are typically very small Full circle contains 360 degrees Each degree contains 60 arcminutes Each arc minute contains 60 arc seconds Angular size measured in degrees arcmin and arcsec of an object depends on its actual size and distance from viewer For an
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