Super, Normal, and Wimpy MoonsSuper, Normal, and Wimpy MoonsCourse AnnouncementsAssignmentsQuiz 5 ResultsQuiz 6 HintsQuiz 6 HintsQuiz 6 HintsQuiz 6 HintsWhat happened to Mars’s atmosphere?Atmospheric Stripping via Solar WindAtmospheric Stripping via Solar WindReverse Runaway GreenhouseInternal Structure of MarsThe Moons of MarsThe Moons of MarsJupiterJupiter vs. EarthJupiter Data Sheet IOrbital PropertiesJupiter Data Sheet IIDifferential RotationDifference in radiiJupiter Data Sheet IIIJupiter’s Atmosphere: CompositionVertical Structure and CloudsAtmospheric “Surface” StructureZonal FlowZonal Flow and alternating wind directionsJupiter’s Zones and BeltsStorms on JupiterGreat Red Spot, Winds, and StormsActual vs. Expected TemperatureInternal StructureJupiter’s InteriorJupiter’s InteriorJupiter’s RingsSuper, Normal, and Wimpy MoonsCredit: Catalin PaduraruWimpyNote: Most astronomers do not like the term Super Moon14% bigger30% brighter(than smallest and dimmest, Wimpy Moon)Super, Normal, and Wimpy MoonsCredit: Catalin PaduraruNote: Most astronomers do not like the term Super Moon7% bigger15% brighter(than normal Full MoonCourse Announcements•Thanksgiving Week planningNo classes Wednesday, 23 Nov.•Last week of Extra Credit Sessions–All Extra Credit materials must be turned in by the start time of the Final Exam.•Quiz 5 Graded•Quiz 6 this Wednesday, 16 Nov.–Hints today•Exam 3 Monday, 21 Nov.–Study materials released as soon as possible–Study session: Thursday, 17 Nov. at 5 PM (Location: TBD)•Final Exam: Thursday, 8 Dec. 2:45 – 4:45 PM•Astronomy Club Interest MeetingFriday, 18 Nov. 12:30 – 1:30 PM Nielsen 307•Online Course Evaluations now available.–Please complete one for this course!!!AssignmentsReading Assignments•Chapter 11: Sections 11.5 – 11.6[Read by Wed., 16 Nov.]•Parallel LecturesCC Astronomy Episode 16: JupiterCC Astronomy Episode 17: Jupiter’s Moons[Watch before Wed., 16 Nov.]Mastering Astronomy•Chapter 10 Homework (short assignment)[Due Wed. ,16 Nov. at 11:59 EST]–Available now on Mastering AstronomyQuiz 5 ResultsAdjusted•Mean: 8.3•Median: 8.5Raw•Mean: 6.8•Median: 7.0Very low attendance; Perhaps hardest quiz•Reward for taking the quiz with lowest attendance to date: +0.5 points•Difficulty Adjustment: +1.0 pts•As this material is a bit more difficult and nuanced, yet integral to understanding stars, I will use some form of all the questions from Quiz 5 on Exam 3•Be sure to know the Formation and Evolution sequences! A few helpful guidelines on next slide.Quiz 6 HintsGeneral concepts to know•What is the runaway greenhouse effect? What planet is it important for understanding its atmosphere?•What is the definition for a habitable zone?•What is a synodic period, and why do we care about synodic periods in relation to space exploration missions?•In what characteristics is Mars similar to Earth? In what ways is it different?–Consider rotation rate, axial tilt, atmosphere, weatherQuiz 6 Covers end of Ch. 9, Ch. 10, and start of Ch. 11Quiz 6 Hints1. What is the largest mountain in the Solar System?A) Mauna Kea B) Mount EverestC) Olympus Mons D) Maxwell MontesE) Caloris HeightsAdditional information to know:•What planet is this located on? What is the name of the largest canyon in the Solar System, and what planet is it on?Sample questionsQuiz 6 Hints2. Which of the major water-related surface features on Mars provides evidence that Mars once had a thicker atmosphere that could support a water cycle including rain, rivers, lakes, and perhaps even oceans?A) Outflow Channels B) Amazonian ChannelsC) Rilles D) Runoff ChannelsAdditional Information•Which feature is indicative of episodic flooding? Which of the two is older and what are their approximate ages?Sample questionsQuiz 6 Hints3. What is the name for a Martian day?A) Sol B) Helios C) Sidereal DayD) Ares E) Mercurial DayAdditional Quiz information:•Material from today’s lecture is fair game. –Which terrestrial planets have moons?–What happened to Mars’s atmosphere?–Blue bolded words about JupiterSample questionsWhat happened to Mars’s atmosphere?Methods of Loss:1. Atmospheric Stripping from Solar Wind2. Jean’s Escape – Lower gravity allows more of the atmosphere to just drift away (All planets slowly leak atmosphere this way)3. Reverse Runaway Greenhouse Effect (Runaway Refrigerator Effect)4. Large impacts blasting away chunks of it at a timeOnce was thick enough to support liquid water, perhaps even global oceansAn artist’s conception of a Solar storm stripping away Mars’s atmosphereAtmospheric Stripping via Solar WindSolar wind erosion of Mars’s atmosphereRecent result (2015) from MAVEN•Amount of atmosphere stripped significantly increases during Solar storms (increased Solar Wind)•Charged solar wind particles carry off ions of Oxygen and Carbon measured by MAVENAn artist’s conception of a Solar storm stripping away Mars’s atmosphereAtmospheric Stripping via Solar WindSolar wind erosion of Mars’s atmosphere•Majority stripped rapidly after loss of global magnetic field•Over the course of the past 4 Billion years or so, this process has ‘eroded’ away the Martian atmosphere.•Sun expected to have higher levels of activity and stronger solar wind 4 billion years ago (=> rapid loss of atmosphere)•Current, non-solar storm stripping rate: 100 grams/s•Calculation reveals that replenishing this loss would provide an atmosphere thicker and capable of supporting liquid waterReverse Runaway GreenhouseSort of the reverse of Venus’s Runaway Greenhouse Effect•Distance from Sun has cooler temperatures, so CO2 locked in rocks (like Earth), and remember when Mars had a thicker atmosphere, the oceans helped with this•Atmospheric loss thins atmosphere and makes it cooler as well (about 4 Gyr)•Colder temperatures make it so CO2 goes into surface and eventually condenses (as CO2 ice; dry ice) on the surface (polar caps)•This makes it colder, so more CO2 out of atmosphere… and it runs away...So called Runaway Refrigerator EffectInternal Structure of Mars•Measurements of the gravity field from spacecraft reveal that a core exists, and it is between 1,500 and 2,100 km in radius.–Avg. Density = 3,900 kg/m3 indicates differentiated and more dense core exists–Lower density suggests a core made of Iron Sulfide (FeS)•Crust is ~50 km thick•Volcanoes hint at convection in mantle•NASA InSight
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