26) Solar Nebula Hypothesis revisited

• Nebulae (gas clouds) and star clusters in the Galaxy (outside our Solar System):
  • the solar nebula started as a dark nebula
  • stars form and light up gas and dust as an emission nebula
  • the Orion Nebula and its star-forming "proplyds"
  • the Eagle Nebula and its star forming regions
• Computer simulations of planet formation in disk (UWa N-body Shop: movie1, movie2, more)
• Abundance of elements in the solar system, very similar to abundances in stars and interstellar gas.
• Links to previous discussion of SNH.

25) Planets orbiting other stars

• Doppler Shift -- movies to show how it works (though light doesn't have the Vsource >= Vlight cases)
• "Extra-solar planets":
  • current catalog
  • click an example to see data (e.g., click on "51 Peg")
• Investigate this physically correct animation of co-orbiting masses
• Direct observations of exoplanets (Fomalhaut and HR 8799, Nov 2008; Beta Pic, Nov 2008)

24) Meteoroids, Meteors, and Meteorites -- Earth Imapcts

• Meteor showers (Geminid meteor shower, Dec 13&14) occasionally produce fireballs (Bone, Indonesia, Oct 09)
• Larger meteoroids that hit the ground are called meteorites
• Iron, stony, and stony-iron meteorites
• Very rare, very large impactors leave craters: over 100 are known on Earth, including:
  • Barringer (Arizona), 1 km across
  • Manicouagan (Canada), 70 km across
  • Mjolnir (Barents Sea), 40 km across
  • Chicxulub (Mexico), 200 km across (the dino-killer?)
  • Peru -- a recent big fall (September 16, 2007)
• Near Earth Object detection and monitoring program.
• Movie showing orbits of NEOs discovered to date (movie showing close calls from 2002; [Animations Page]).

23) Comets

• View from Earth: round coma and a tail (or two: dust and gas) -- many images of different comets
• Nucleus is a "dirty snowball," irregular in shape
• Missions to several comets: including Stardust & Deep Impact
• Comets in 2008/9?: none predicted to be naked-eye-notable
• Meteor showers/storms (Leonids in 2008 & 2009), superbolide over Colorado (Dec 8, 2008)

22) The Kuiper Belt

• discovery of KBOs: movie
• click on The 1000 km Scale KBOs that catylized the Pluto/planet redefinition: Eris, Sedna, Haumea, Orcus, and Quaoar
• movie showing orbits of trans-Neptunian objects (lots of different sub-types)

21) Pluto -- is it a planet?

• International Astronomical Union (organization of professional astronomers):
  • Resolution defining "planet" (and redefining Pluto as a "dwarf planet")
  • Pluto's two "new" moons named Nix and Hydra
  • Eris: the third dwarf planet (Sep 2006; formerly known as 2003 UB313, aka "Xena")
  • Another new definition: Plutoid (Jun 2008)
  • Makemake: the 4th dwarf planet (Jul 2008; formerly 2005 FY9)
  • Haumea: the 5th dwarf planet (Sep 2008; formerly 2003 EL61)
• Thoughts from Mike Brown, discoverer of several new "dwarf planets"
• New Horizons -- first ever spacecraft to Pluto (to arrive in 2015)

20) Jovian moons & rings

• Cassini orbiter (currently at Saturn) and the Huygens probe to Titan
• Galileo orbiter (most recent mission to Jupiter) and its atmosphere probe
• movie of orbiting moons
• giant planet satellite page (orbial properties of regular and irregular satellites)
• Saturn's rings and moons (gravitational resoncances, shepherds)
• ring moonlets Atlas & Pan (cycling particles in/out of rings)
• spiral density waves in rings
• movie of "spokes" in Saturn's rings (something non-gravitational)

19) Uranus & Neptune (ice giants)

• NASA mission: Voyager 2 only, none planned.

18) Jupiter & Saturn (gas giants)

• Jupiter: NASA missions past/present/future, including Galileo and its atmospheric probe
• Saturn: NASA missions past/present/future, including Cassini
• Movies of Jupiter's rotation and winds (rotation removed)
• Movie of Saturn seen from different angles

17) Asteroids

• Like planets, move "through" background stars, but are "star-like" (aster-oid) -- BGSU obs of 511 Davida & 704 Interamnia
• They orbit around the Sun, mostly in a belt between Mars & Jupiter (orbits of selected asteroids)
• Examples: Gaspra, Ida, Mathilde, and Eros (visited by spacecraft) and Castalia (radar image), sizes
• NASA missions: current = "Dawn" mission to Vesta (2012) & Ceres (2015)
• Mars's moons Phobos and Deimos, captured asteroids?

16) Mars:

• Orbiters: Mars Global Surveyor, Mars Odyssey, Mars Express, Mars Reconnaissence Orbiter:
  • high resolution global map
  • Mars Orbiting Laser Altimeter: Google Mars!, MOLA Map
  • South vs North hemisphere dichotomy
  • craters
  • volcanos repaved some of surface (Olympus Mons)
  • Valles Marineris (closeups and other canyons)
  • Mars image of the day
  • Thermal Emission Spectrometer (TES):
    • thermal (blackbody) spectrum (70°F)
    • mineral spectrum deviates slightly from pure thermal spectrum (dips due to mineral)
    • different minerals have different spectra (dips)
    • take spectra of surface: determine surface temps & mineral maps (scroll down)
• Landers: Vikings, Pathfinder, Spirit/Opportunity, Phoenix:
  • rover design & instruments:
    • weather station (on lander)
    • alpha-proton-X-ray spectrometer (hit rock with alpha-particles, analyze rebounding particles & X-rays determines types & #s of atoms present)
    • mini-TES for up-close minerology
• road trips (#1, #2, #3)
• Evidence for water in the past (also see Figs 40.7-13):
  • flow channels (sudden flash-floods?) and meandering stream channels (slower, long-term flow)
  • "seeps" and gullies in crater walls (super-high-res gullies)
  • outcroppings of rock, many layered (sandstone?) some contain hematite "blueberries"
  • volume of water-ice (not carbon dioxide "dry ice") in the polar caps
  • gamma-ray spectrometer map of hydrogen (water?) distrubution in the soil/rocks
• Other spacecraft missions: Past, present, and future.
• More images and text at nineplanets.org.
• Aha, the only other terrestrial planet with moons! Phobos and Deimos.

15) Venus:

• Thick atmosphere, mostly carbon dioxide gas (so greenhouse effect operates very efficiently), with a perpetual blanket of clouds (sulfuric acid, etc).
• Slow planetary rotation is "backwards," possibly caused by a cataclysmic impact on proto-Venus. Slow rotation may explain lack of magnetic field.
• Soviet landers: Venera 9, Venera 13, and Venera 14 (pictures and on-site measurements)
• NASA radar mappers: Magellan (1990-1994) high resolution global map:
  • volcanos with lava flows akin to ones on Earth
  • local tectonics produced cracks and ridges in crust
  • coronae and arachnoids may indicate upwelling plumes of hot mantle that fail to penetrate the thick crust.
  • impact craters (few suggesting young surface, 500 Myr old, only large ones b/c small meteors burn up in atm)
  • hints of surface wind blowing material (some wind erosion or deposition?)
• Other spacecraft missions: Past, present, and future. ESA's Venus Express is there now.
• More images and text at nineplanets.org.

14) Mercury:

• Lots of images and supporting text at nineplanets.org (eg lobate scarps & impact basin)
• Proportionally large metal core (high average density of planet) but weak magnetic field (due to slow planet rotation and/or cooler, less convective core due to smaller size)
• Spacecraft:
  • Mariner 10 (1970s; more detail)
  • MESSENGER (3 of 3 flybys completed, orbit in 2011), MESSENGER from Johns Hopkins
  • BepiColumbo (ESA, launch in 2013)
• Thermal (black-body) radiation -- wavelength of peak intesity (lambda-max) gets bluer as the source gets hotter.
• Infrared pictures of everyday stuff, etc.
• Infrared radiometers and spectrometers are used to measure the intensity and wavelength of infrared light emitted from a planet's surface and remotely measure its temperature.

13) Earth's Moon:

• Web activity developing a simple model of tides in Earth's oceans, NOAA tides online.
• More info and pictures of the moon's surface from NinePlanets.org
• Images of the moon: highland terrain, maria, far side; Apollo 11 and Apollo 12 landing sites.
• Mare Humorum, Taurus-Littrow Valley, more highland terrain.
• Maps of moon showing whole moon, maria, mountains/craterwalls, etc: its fun to turn the moon!
• Crater features: crater rim, central peak, rays, smooth dark crater floor; sizes range from 1000 km (rare) to tiny pits (everywhere).
• Breccia and lunar dust due to impacts, inferred rate of cratering over lunar history, impacts still happening.
• Earth's impact craters.
• Apollo moon missions: highlights in video and still photos (NASA image archive and more photos & videos).
• Un-crewed missions to the moon, past, present and future.
• Visit a moon rock at the Neil Armstrong Museum in Wapakoneta, OH, or the museum at NASA/Glenn in Cleveland.
• A discussion of lunar landing conspiracy theories by BGSU undergrad Gloria Doller (2003).
• Federal funding (Office of Management and Budget)
• Lunar formation: computer simulation (mathematical model) & artist's conception
• Websites for Apollo reading and Moon, Mars & Beyond (also, opposition article, NASA MMB site).

12) The Earth:

• Magnetosphere: 2D-drawing, 3D-movie, Northern Lights, maps and images of auroras seen from space.
• Atmosphere:
  • Ozone Layer thickness varies seasonally with a hole developing in austral spring. The hole has grown larger (size & amount of ozone lost) since the 1970s. NASA and other organizations are monitoring its size. The ozone hole issue is not connected with Ozone Action Days, which are intended to minimize smog/pollution due in part to an excess of ozone low in the atmosphere over city environments.
  • Greenhouse effect (nice animated explanation), excess carbon and global climate change, Intergovernmental Panel on Climate Change and recent reports (Working Group 1 Summary).
• Surface:
  • plate tectonics movie, ocean spreading ridge, subduction zone, US Geological Survey, seafloor age map (sediment thickness).
  • Earthquakes, seismograph & chart, earthquake animations from PBS "Savage Earth" series.
  • Andy's hike on a Chilean volcano.
• Some main points in Earth history based on the fossil record.
• Convection in the mantle drives plate tectonics, and in the liquid core creates Earth's magnetic field.

11) Solar System Structure and Origins:

• Visualize the solar system's disk shape and common direction of revolution (neo orbits)
• Radioactive decay movie (scroll down to the Flash movie and choose different radioactive elements) [movie #2, #3]
• More on geologic time and using radioactive decay to determine ages of rocks
• Nebulae (gas clouds) and star clusters in the Galaxy (outside our Solar System)... the solar nebula started as a dark nebula
  • Ex: Eagle Nebula (M16) -- wide-field view, the "fairy," and "pillars," "pillars2," and "EGGs." Other globules.
• Computer simulations of planet formation in disk (UWa N-body Shop: movie1, movie2, more)

• remember, granulation in the sun is due to convection, not magnetic fields, so it is not technically "solar activity"
• "magnetic trilobite" video -- erupting magnetic field
• X-ray jets may help to heat the corona, in addition to vibrating magnetic field lines directly moving atoms in the corona
• spaceweather.com = today's solar activity and forecasts (plus other news and pictures)
• solar cycle = number of sunspots (prominences, flares, etc) varies with ~11 year cycle.

• Periodic Table of the Elements (click to get visuals of different elements) ... some elements we will meet often in class:
  • hydrogen (¹H) has 1 proton, 0 neutrons, and 1 electron (when neutral, i.e., not ionized)
  • helium (⁴He) has 2 protons, 2 neutrons, 2 electrons when neutral
  • carbon (¹²C) has 6 protons, 6 neutrons , and 6 electrons when neutral
  • iron (⁵⁶Fe) has 26 protons, 30 neutrons, and 26 electrons when neutral