Total Solar Eclipse – Marshall Island, 2009Course AnnouncementsAssignmentsQuiz 1 HintsQuiz 1 HintsMotion of the MoonPhases of the MoonMoon PhasesExample Quiz QuestionExample Quiz QuestionEclipsesEclipses - GeneralA more true perspectiveLunar EclipsesMotion of the MoonMotion of the MoonSolar EclipsesTotal Solar EclipseSolar EclipsesQuiz 1 – Possible QuestionsEclipse SeasonsEclipse SeasonsMeasuring DistancesAngular MeasurementAngular MeasureAngular MeasureApproximate Angular SizesMeasuring DistancesLocal Cosmic DistancesLocal Cosmic DistancesLocal Cosmic DistancesOur largest baselineTotal Solar Eclipse – Marshall Island, 2009Total Solar Eclipse – Marshall Island 2009. Credit: V. RusinCourse 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: LINDSAYA152F2016AssignmentsReading Assignments•No new readingParallel 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 HintsA few types of questions to expect1. The time period that it takes to rotate exactly 360° about its rotation axis is known as?A. Solar DayB. Tropical YearC. Synodic MonthD. Sidereal DayE. Nautical DayPossible Variants:I ask what the noon-to-noon time period is.I ask which is longer, the Solar or Sidereal DayQuiz 1 HintsA few types of questions to expect2. ____________ on the Celestial Sphere is analogous to latitude on EarthA. North Celestial PoleB. South Celestial PoleC. EclipticD. Right Ascension E. Declination-Possible variants: I ask what is analogous to longitudeI give the Celestial Coordinate and you give the Earth analogMotion of the MoonEarth – 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 MoonDue to relative position of Sun, Earth, and MoonKey Concepts:1. Moon is bright because of reflected sunlight2. Half of the Moon is always illuminated3. The phase we see is due to our view of the illuminated portion4. Takes about 4 weeks to complete synodic period(Quarter)~ 3 Weeks LaterIncomingSunlight~ 4 WeeksDay 0(New)~ 1 Week Later(Quarter)2 Weeks Later(Full)Moon PhasesIf 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 SimulatorIncomingSunlightSketch of TODAY’s MoonExample Quiz QuestionA) 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?IncomingSunlightSketch of TODAY’s MoonExample Quiz QuestionA) 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 MoonEclipsesDue to the alignment of Sun - Earth - MoonCredit: Geoff SimsCredit: Forrest EganTime lapse images ofTotal Solar EclipseTotal Lunar EclipseCredit: Cat Wu & S. LindsayCredit: Alfredo Garcia, Jr.Eclipses - GeneralEclipses occur when the Sun, Moon, and Earth form a straight line.Note the 5.20 inclinationSolar Eclipse Alignment Lunar Eclipse AlignmentEclipses 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°A more true perspective5.2 Degree Inclination5.2oFor an eclipse to occur, the angle between the Sun, Earth, Moon line is very near to 00Maximum (5.20) extent below Sun – Earth LineViewed “Edge On”Maximum (5.20) extent above Sun – Earth LineTwo points (in front and behind) where 0o between Sun – Earth LineLunar 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)Lunar EclipsesMotion of the MoonSolar Eclipses•Moon is between Sun and Earth => New Moon•Partial when only partially shadowed (in penumbra)•Total when entirely shadowed (in umbra)UmbraPenumbraCompletely shadowedPartially shadowedMotion of the MoonSolar 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 minutesPath of Totality for August 21, 2017 Solar EclipseSolar EclipsesOnly occur during New MoonTotal Eclipse when area is in the UmbraPartial Eclipse when area is in the Penumbra•Moon is between Sun and Earth => New Moon•Partial when only partially shadowed (in penumbra)•Total when entirely shadowed (in umbra)Total Solar EclipseDuring a total solar eclipse you can see the outer atmosphere of the Sun called the CoronaTOPTotal Solar Eclipse – Marshall Island 2009. Credit: V. RusinBOTTOMTotal Solar Eclipse – Svalbard, April 2015. Credit: M. DruckmüllerSolar EclipsesThe 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 occursAnnular eclipseMay 20, 2012Quiz 1 – Possible Questions1) 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 Earth2. 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 MoonIncomingSunlight~ 4 WeeksDay 0(New)~ 1 Week Later(Quarter)2 Weeks Later(Full)Eclipse SeasonsEclipses 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 SituationNodeNode: point in Moon’s orbit where it crosses the EclipticEclipse SeasonsMust be in this in this alignment. The precise alignment
View Full Document
Unlocking...