Astronomy 101 The Solar System Tuesday, Thursday 2:30-3:45 pm Hasbrouck 20 Tom Burbine [email protected] CourseOffice HoursHomeworkAstronomy InformationExam #4Exam #4Class Averages as of todayFinalHW #20 and 21HW #18 (late) and #19 (late)Student PresentationsWhy we should worry about asteroids and comets?2009 DD45Tunguska2008 TC399942 ApophisCometsWhen were comets first discovered?Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Tempel 1 pre-impactHalley’s CometCometsTypes of CometsCometsComet HalleyCometsCompositionAn Icy Conglomerate NucleusSlide Number 38Slide Number 39Slide Number 40Periodic Comet Halley, 1986Slide Number 42Comet WestWhere does cometary dust originate?Origin of Cometary SilicatesSlide Number 46Slide Number 47Stardust MissionAerogel - Peter TsouSlide Number 50Slide Number 51Slide Number 52Slide Number 53Encounter with Comet 81P/Wild 2Slide Number 55Slide Number 56Slide Number 57Slide Number 58Wild 2 image superimposed on jetsDeep ImpactDeep ImpactSlide Number 62VideosImage from Deep Impact Any Questions?Astronomy 101The Solar SystemTuesday, Thursday2:30-3:45 pmHasbrouck 20Tom [email protected]• Course Website:– http://blogs.umass.edu/astron101-tburbine/• Textbook:– Pathways to Astronomy (2nd Edition) by Stephen Schneider and Thomas Arny.•You also will need a calculator.Office Hours• Mine• Tuesday, Thursday - 1:15-2:15pm•Lederle Graduate Research Tower C 632• Neil• Tuesday, Thursday - 11 am-noon • Lederle Graduate Research Tower B 619-OHomework• We will use Spark•https://spark.oit.umass.edu/webct/logonDisplay.dowebct• Homework will be due approximately twice a weekAstronomy Information• Astronomy Help Desk• Mon-Thurs 7-9pm• Hasbrouck 205•The Observatory should be open on clear Thursdays • Students should check the observatory website at: http://www.astro.umass.edu/~orchardhillfor updated information• There's a map to the observatory on the website.Exam #4• Hard to make questions that everybody gets right:23 out of 274 (8% of class) got this question wrong• Which spacecraft landed on the surface of Venus and took pictures of the surface?– Venera 9• 8 out of 274 (3% of class) got this question wrong • Caloris Basin and Hellas Basin are both – large impact craters•Exam #4• Class average was 75.4• Grades ranged from 45s to 100Class Averages as of today• For people who took all 4 tests:• Class average now (80% Exam, 20% HW) is 80.6• Grades range from a 98.3 to a 54.2•This average will go up when the lowest exam grade is dropped after the final and the lowest HW grade is droppedFinal• Cumulative• Monday - 12/14 • 4:00 pm•Hasbrouck 20• Review Session• Sunday -12/13• 3:00 pm• Hasbrouck 134HW #20 and 21• Due todayHW #18 (late) and #19 (late)• I have put HW #18 (late) and #19 (late)• All calculations• On blogStudent Presentations• Life on Mars• Life on Europa and Titan• Life on extrasolar planetsWhy we should worry aboutasteroids and comets?2009 DD45• On March 2, 2009:• NEA 2009 DD45 came within~70,000 km of the surface of the Earth•Diameter between 21-47 mhttp://www.skyandtelescope.com/observing/highlights/40504617.htmlOver 36 minutesTunguska• This object is believed to be the same size as the object that exploded over Siberia in 1908• About 1,000 times as powerful as the bomb dropped on Hiroshimahttp://geophysics.ou.edu/impacts/tunguska_dc.gifhttp://dustyloft.wordpress.com/2008/06/2008 TC3• 2-3 m object that entered the atmosphere over Sudan on October 7, 2008• Burned up before it reached the ground•Fragments foundhttp://en.wikipedia.org/wiki/File:2008TC3-groundpath-rev.pnghttp://i176.photobucket.com/albums/w189/walcom77/2008TC3_fragments.jpg99942 Apophis• Initially thought to have a high probability (up to 2.7%) of hitting Earth in 2029• ~270 meters in diameter• Impact probability with Earth for April 13, 2036 is calculated as 1 in 45,000http://en.wikipedia.org/wiki/File:Apophis_pass_zoom.svg2029Comets• Comets can also hit usWhen were comets first discovered?• Comets have been known since the earliest days of mankind• Usually thought to be unlucky• Attacks by heavenly beings on terrestrial people Comet Ikeya-Zhang153P/Ikeya-ZhangPeriod of 341 yearsChinese, written on silk about 168 BC:Astrological omens, such as ‘war comes’, ‘general dies’, 'small war, corn plentiful'Roman coin depicting soul of Julius Ceasaras a cometComet Halley in 1145From English MonasteryComet Halley in 1066Bayeaux TapestryFresco by Giotto, ca 1300From German manuscript, ~ 1400 ADMoctezuma II in 1516Comet Ikeya-ZhangCopyright ©2002 Michael JagerComet Wild2By StarDustTempel 1 pre-impactComet Tempel 1 before impact from Deep Impact 5 x 7.6 kmHalley’s Comet• Edmund Halley figured out that the orbit of the comet of 1682 was nearly the same as those of two comets which had appeared in 1531 and 1607 • Halley concluded that all three comets were in fact the same object returning every 76 years • Halley predicted its return for 1757. • Halley's prediction of the comet's return proved to be correct, although it was not seen until December 25, 1758Comets• Usually named after discoverer (or person who computed its orbit)•Comet Halley• Number given when discover (or discoverers) have discovered numerous comets• Comet Shoemaker-Levy 9Types of Comets• Short period comets – periods < 200 years•Long-Period Comets – periods > 200 yearsComets• Comet West• Blue tail –gases, white tail – dust particlesComet Halley• Giotto image• Dimensions - 16 x 8 x 8 kmComets• Called Dirty Snowballs by Fred Whipple• Because they are mixtures of ice and dustComposition• Rock• Dust• water ice• frozen gases such as carbon monoxide, carbon dioxide, methane, and ammonia.An Icy Conglomerate NucleusIn 1950, Fred Whipple showed that comet activity can be explained by sublimation of water ice from an icyconglomerate nucleus a few km in size. The sublimationrate can be computed as a function of temperature.http://en.wikipedia.org/wiki/Image:Comet_tails.gifPeriodic Comet Halley, 1986Our first look at a comet nucleus…(Comet Halley will return in 2061)GiottoComet P/Halley Giotto HMCComet WestComet WestWhere does cometary dust originate?Origin of Cometary Silicates•Crystalline olivine and pyroxene condensed at high T, most
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