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The ecliptic: path of the Sun through the sky, and the location of the zodiac ... of primitive stone, which are less dense and show signs of volatiles and carbon. ... – PowerPoint PPT presentation

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Title: Review for Test 1


1
Review for Test 1
  • 2-27-2007

2
The Lectures
  • 1. Review of the syllabus.
  • 2. Where we are planetary motion, eclipses.
  • 3. The Sun nuclear energy, solar activity.
  • 4. The planets, density, atmospheres,
    spectroscopy.
  • 5. Telescopes, spectral windows, albedos.
  • 6. Solar System Formation
  • 7 8. Meteorites classifications, radio-isotope
    dating
  • 9. Asteroids
  • 10. Comets

3
Lecture 2 History etc.
  • The ecliptic path of the Sun through the sky,
    and the location of the zodiac
  • The seasons equinoxes and solstices.
  • Phases of the Moon, what causes them, eclipses.
  • Aristotles geocentric universe.
  • Retrograde motion of the planets.
  • Copernican revolution, heliocentrism.

4
Lecture 2. Laws of motion
  • Keplers Laws of planetary motion
  • 1. Law of Orbits Each planet moves in an
    elliptical orbit about the Sun, with the Sun at
    one focus of the ellipse.
  • 2. Law of Areas A planet sweeps out equal areas
    in equal time during its orbit.
  • 3. Law of Periods The cube of the distance
    divided by the square of the period is a
    constant.
  • P2 a3
  • Galileos discoveries
  • Newtons understanding of gravity
  • Escape and orbital velocity

http//www.eso.org/outreach/eduoff/edu-prog/catcha
star/casreports-2004/rep-070/
5
Lecture 3-The Sun
  • Parallax, Temperature Scales
  • Matter
  • Atoms vs. elements
  • Isotopes vs. ions
  • The nucleus, protons, neutrons and electrons
  • Hydrogen vs. Helium
  • Molecules and compounds
  • Radiation, light, waves and particles, speed of
    light, the EM spectrum
  • Parts of the Sun
  • Core Where fusion occurs, T 15 million K,
    Energy released as Gamma Rays
  • Radiation Zone Outside the core, gamma rays are
    absorbed and reemitted constantly
  • Convection Zone Above the radiation zone, below
    the visible surface, energy is transported via
    convection, similar to a rolling water in a
    boiling pot.
  • Photosphere visible surface, 5800 K
  • Chromosphere Above the photosphere, looks pink
    during eclipses
  • Corons Very hot layer of ionized gas, 4 million
    K, is the beginning of the Solar Wind.

6
Lecture 3- The Sun
  • The Sun uses 4 million tons of matter per second,
    fusing H to He.
  • E mc2 relates how much energy is created when
    mass is lost in nuclear reactions.
  • Solar activity
  • Sunspots cool dark patches on the surface caused
    by material trapped in magnetic fields.
  • Flares eruptions from the surface associated
    with breaking of magnetic field lines.
  • CMEs Huge ejections of matter from the Corona.

7
Lecture 4- The planets
  • Sizes and densities
  • Terrestrial Mercury, Venus, Earth and Mars
  • Giant Jupiter, Saturn, Uranus, and Neptune.
  • Icy/KBO/other Pluto, Eris, and other KBOs.
  • Hints on composition
  • Mercury has a higher density than we might
    expect.
  • Giant planets have very low densities
  • Clearly the planets must have different
    compositions.

8
Lecture 4 Forms of matter
  • Rocks
  • Igneous (e.g. basalt)
  • Sedimentary (e.g. limestone)
  • Metamorhpic (e.g. marble)
  • Gas Atmospheres can be acquired
  • Direct Capture from the original Solar Nebula
    (primary)
  • Outgassed from rocks after differentiation
    (secondary)
  • From cometary impacts (secondary)
  • How to lose your atmosphere?
  • Thermal escape the energy of the gas is too
    great and velocities grow larger than escape
    velocity
  • Impacts comets or asteroid blow the atmosphere
    away
  • Solar Wind The fast-moving Solar Wind blows the
    atmosphere away

9
Lecture 5 Telescopes etc.
  • Astronomers have two options to study distant
    bodies
  • In situ investigations directly studying the
    object,
  • Mars rovers,
  • Galileo atmosphere probe.
  • Remote sensing studying the radiation emitted or
    reflected from a distant body,
  • Earth-based telescopes,
  • Spacecraft orbiting Earth, or other planets.
  • Planets are cooler than the Sun, and cooler
    objects are redder (Wiens law).
  • Because of this planets emit thermal radiation at
    Infrared wavelengths (IR), instead of visible
    like the Sun.
  • The wavelengths that we can observe at are called
    atmospheric, or spectral windows

10
Lecture 5 Telescopes
  • Planets also dont reflect perfectly. How much
    light they do reflect is called its albedo.
  • Moon 0.11
  • Venus 0.75
  • Average KBO or asteroid 0.04 0.15
  • How much does size matter?
  • Collecting area increases (proportional to D2)
  • Spatial resolution (proportional to D)
  • Working by way of the photoelectric effect, CCDs
    are grids of pixels, which convert photons into
    electric charges.

11
Lecture 6 Solar System Formation
  • Facts we can use to figure stuff out
    Composition
  • The sun is almost all H and He, therefore the
    solar nebula was mostly this also.
  • The inner planets dont have a lot of volatiles.
  • More facts orbits and rotations
  • Planets orbit in the same plane, mostly
  • Planets orbit in same direction.
  • Sun rotates in the same direction

12
  • Angular momentum is the product of three
    quantities mass, size (radius) and rotation
    speed (or velocity)
  • L mrv

Figure Universities Corp. For Atmospheric
Research (UCAR)
13
The disk/planet formation
  • The central parts of the nebula were very hot
    over 10,000 K.
  • Going outwards in the nebula, the temperature
    drops, and different compounds condense out at
    different distances from the protostar
  • Calcium, Aluminum oxides first,
  • then Iron-Nickel alloys (by 0.2 AU, Mercury),
  • Magnesium silicates and oxides next (by 1.0 AU),
  • Olivine and Pyroxene (Fe-Si-O compounds),
  • Feldspars (K-Fe-Si-O compounds),
  • Hydrous silicates,
  • Sulfates,
  • And finally ices (water ice by 5.0 AU).
  • This radial variation in composition in the
    nebula is one cause of the variation in
    composition of the planets with solar orbit
    distance.

14
Lecture 7 Meteorites
  • Major mineralogical types Stony, Iron,
    Stony/Irons
  • Origins Primitive (chondrite), Differentiated
    (achondrite), Breccias
  • Primitives are all stones, carbonaceous or other
    kinds.
  • Differentiated can be any mineralogical type.
  • Breccias are usually crustal material from
    asteroids or planets, could be primitive or
    differentiated.
  • Falls and Finds.
  • We FIND mostly irons and stony-irons.

15
Lecture 7 Meteorites
  • The few orbits we have for meteorites all suggest
    Main Belt origins
  • Primitives are old (4.5 Gyr), have chondrules,
    some iron, and are often breccias.
  • Carbonaceous Chondrites are a type of primitive
    stone, which are less dense and show signs of
    volatiles and carbon.
  • Two big meteorites, Tagish Lake and Murchison are
    C.C. which contain amino acids

16
Lecture 8 Differentiated
  • Differentiated meteorites lack chondrites, and
    are called achondrites.
  • Irons have up to about 10 nickel, and have a
    crazy pattern, widmanstatten, due to slow
    cooling.
  • These meteorites from the differentiated
    bodies
  • Stony/Irons, also come from differentiated
    bodies, probably the boundary between core and
    crust.
  • Stony Irons are dated to about 4.4 or 4.5 Gyr
    years, slightly younger than primitives.
  • Eucrites have been found to come from the crust
    of the asteroid Vesta
  • Basalts are lighter rocks, from asteroid crusts.
    Some have been found to come from Mars or the
    Moon.

17
Lecture 8 radioactivity
  • Two main types,
  • Alpha Decay The emmited particle is a helium
    nucleus 2 protons and 2 neutrons.
  • Beta Decay The emitted particle is either an
    electron or positron. This particle is emitted
    from the nucleus, no the swarm of electrons
    around the nucleus.

18
Lecture 8 Dating rocks.
  • When we have a closed system, or a system is no
    longer having its isotopes modified. Then we can
    track the amount of
  • Parent nucleus (original isotope) as it
    decreases,
  • Daughter nucleus (newly created after decay) as
    it increases.
  • We need to know the following things for dating.
  • The current parent/daughter isotope ratio
  • The original parent/daughter isotope ratio
  • The rate of decay.

19
Lecture 9 Asteroids
  • The number of asteroid follows 1/D2 instead of
    1/D3. This means we can estimate the total
    mass.
  • The Moon is 20 time more massive than all the
    asteroids.
  • Orbits and rotations are easily measured, sizes
    are not,
  • Occultations, get size by watching it eclipse a
    star
  • Spectroscopy, use reflection and emission at
    different wavelengths to estimate size.

20
Lecture 9 asteroid orbits
  • They live between 2.2 and 3.3 AU.
  • The gaps in the asteroid belt, are caused by
    resonances with Jupiters orbit.
  • There are safe resonances with Jupiter, like 11,
    which is what the Trojans are on.
  • Asteroid families have similar orbits and
    spectra, suggesting they are collisional remnants
    of one large parent body.

21
Lecture 9 asteroids
  • Asteroid types
  • C-type carbonaceous, dark, with water,
    primitive
  • S-type Stony, with silicates primitive
  • M-type metallic, brighter differentiated
  • S-type are in the inner Main Belt, C-type are in
    the outer MB, and are more numerous (75)
  • Densities are all over the place due to porosity

22
Lecture 9 asteroids
  • WE also find asteroids
  • At Jupiters lagrange points, the Trojans
  • Near Earth, NEAs
  • Out around the Giant planets, Centaurs
  • The more distant, the redder they appear.
  • Asteroids we have gone to
  • Gaspra, by galileo, flyby, irregular shape
  • Ida, found a small moon, lots of craters
  • Mathilde, huge crater, low porosity
  • Eros, orbited and landed, missing craters and
    moving dust.
  • Itokawa, orbited and landed, rubble pile
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