Presentation on theme: "The Jovian Planets COMPARISON OF SIZES: Gas Giants Ice Giants."— Presentation transcript:
The Jovian Planets COMPARISON OF SIZES: Gas Giants Ice Giants
1.Distance from the Sun 2.Size & Mass 3.Chemical Composition 4.Rotation 5.Moons & Rings …and what do extrasolar planets tell us? Main differences between terrestrial and jovian planets:
1. Jovian planets follow circular orbits farther from Sun than terrestrial planets outermost terrestrial planet (Mars): 1.5 AU innermost Jovian planet (Jupiter): 5.2 AU COMPARE ORBITS jovian planets probably formed where icy material could condense
Orbits of Extrasolar Planets most detected planets have orbits smaller than Jupiter’s planets at greater distances are harder to detect… star wobbles less wobble changes slowly “observational bias”
2. Jovian planets bigger and more massive than terrestrial planets 4 to 11 Earth’s size Each has more mass than all terrestrial planets Jupiter has more mass than ALL planets More raw material available (ices, hydrogen and helium gases, as well as rock) for jovian planets
3. Jovian planets have different composition than terrestrial planets ATMOSPHERES: spectrums reveal mostly hydrogen compounds DENSITY: low densities require mostly hydrogen and helium methane responsible for bluish colors
Jupiter Clouds: colors from materials condensing at different depths: ammonia(NH 3 ) ammonium hydrosulfide (NH 4 SH), water (H 2 O), DEEPEST SHALLOWEST
Neptune “Great Dark Spot” – now gone methane (CH 4 ) ice clouds
Thought Question: How does the escape velocity for Saturn (mass: 95 M earth, radius 9.5 R earth ), compare to Earth’s? A.about 20 times larger B. about 20 times smaller C. about 10 times larger D. about 10 times smaller E. about 3 times larger F. about 3 times smaller
Thought Question: How does Uranus’ (about 4 Earth radii, 15 Earth masses) density compare to Jupiter’s (about 11 Earth radii, 318 Earth masses)? (Enter the ratio rounded to one decimal place.)
Interiors Jupiter, Saturn: probably formed first and captured more H and He (closer to Sun, icy planetesimals and gas were common) compressed metallic hydrogen probably causes large magnetic fields Uranus, Neptune: mostly compressed “icy” material
Extrasolar Planet Densities jovian planets in solar system: 0.7 - 1.7 g / cm 3 jovian-mass extrasolar planets have wide range in densities: 0.1 - 9 g / cm 3 !
4. Jovian planets rotate faster than terrestrial planets Earth: 24 hours Jupiter: 9 hours 50 min (fastest) Uranus: 17 hours 14 min (slowest) jovian planets got a lot of angular momentum from gases they pulled in
Thought Question: What should happen to a rapidly spinning planet if it is mostly made of materials that aren’t solid? A.It will bulge outward at its equator. B.It will bulge outward at its poles (like a football). C.It will expand in all directions. D.It will pull inward all over. E.Nothing really - it will just spin normally.
Oblateness “flattening” caused by planet’s rotation – shape is not a sphere The more of the interior that is fluid, the more it will bulge at its equator when it rotates Example: tossing pizza
5. Jovian planets have many moons and rings COMPARE Terrestrial planets: Earth: 1 big moon Mars: 2 asteroid- sized moons Jovian planets: Many asteroid- sized moons, some larger Mostly ice, rock, or combination
5. Jovian planets have many moons and rings No terrestrial planets have rings All Jovian planets have rings
visibility of rings depend on how reflective they are
Light Waves … caused by accelerating electrial charges wavelength (λ): distance between successive wave crests different colors have different wavelengths: frequency (f): number of wave crests that pass per second units: number per second, or Hertz (Hz) for sound waves, frequency = PITCH speed of light (c): WAVELENGTH BLUERED 700 nm400 nm
The Electromagnetic Spectrum visible light is just a small part of the entire spectrum: increasing f decreasing
Thought Question: What wavelength will radio waves from station “90 FM” have? (FM station frequencies are given in mega-Hertz, or 10 6 Hz.) (Enter the answer in m to two significant digits.)
Light Waves energy (E): higher frequency larger energy WAVELENGTH BLUERED Thought Question: Which has higher energy? 1.Red light 2.Blue light
Spectrum SPECTRUM: a way of describing a MIXTURE of light: how intense are different colors? Roughly equal mixture of colors appears WHITE: LIGHT INTENSITY WAVELENGTH V I B G Y O R LIGHT INTENSITY WAVELENGTH V I B G Y O R Unbalanced mixtures are tinted by most intense colors:
Observing a Spectrum SELECT SPECIFIC WAVELENGTH RANGES (FILTERS) SPLIT LIGHT BY WAVELENGTH (PRISMS, CDs) greyscale (lighter = more intense)
Thought Question: If I project dots of red and green light on the screen, what will you see where they overlap? A.A yellow dot B. A brown dot C. A blue dot D. A black dot E. A white dot A. A blue dot B. A brown dot C. An orange dot D. A black dot E. A white dot If I project dots of blue, red, and green light on the screen, what will you see where they overlap?
The Importance of Spectrums Atoms of each element … absorb and emit unique combinations of colors AND work the same way across the universe Spectrums can be used to: identify chemicals measure temperature measure speeds
Thermal Radiation hot, opaque objects radiate light in a way that depends only on temperature as T increases: light of all wavelengths gets brighter wavelength of most intense light gets shorter (bluer) BLACK (no visible light) REDORANGEYELLOWWHITE WHAT WE SEE BY EYE:
Thermal Radiation Stefan-Boltzmann Law: brightness at surface of hot object (also called flux) (energy released per second per area) FOR SAME AREA, HOT SURFACE RELEASES LIGHT FASTER ALL COLORS GET MORE INTENSE (a constant)
Thermal Radiation thermal radiation is released at all wavelengths, but… Wien’s Law: most intense light is released at this wavelength: HOTTER=BLUER Sun: Blackbody Applet Blackbody Applet 2
Thought Question: The hottest stars can be more than ten times hotter than the Sun at their surfaces. How much brighter (energy released per m 2 per sec) would the surface of such a star be compared to the Sun? What would the peak wavelength of such a star be (in nm) if the Sun’s peak is at around 500 nm?
Star Luminosity Stars release THERMAL RADIATION: brightness of each piece of surface only depends on temperature Apply Stefan-Boltzmann Law: flux from each piece of star’s surface star’s surface area luminosity (L): total amount of energy released per time units: Watt (W): 1 W = 1 J / s property of a star: its “power”
Thought Question: The graph below shows the blackbody spectra for three different stars. Which of the stars is at the highest temperature? A.Star A B.Star B C.Star C
Thought Question What kind of spectrum would you see if you were looking in the direction shown by the arrow? A. continuous (thermal radiation) spectrum B. absorption line spectrum C. emission line spectrum transparent gas cloud star
Types of Spectrum transparent gas cloud (atoms can absorb specific wavelengths of light AND emit the same wavelengths) star (source of thermal radiation – frequent collisions between electric charges) ABSORPTION THERMAL RADIATION EMISSION WHAT YOU SEE:
Thought Question: When I pass a jug of clear blue liquid in front of the light bulb, what will happen? A.The jug will make the violet, blue, and green light more intense. B.The jug will make the yellow, orange, and red light more intense. C.The jug will remove most of the violet, blue, and green light. D.The jug will remove most of the yellow, orange, and red light.
Kinds of Spectrum ABSORPTION LINE: transparent material in front of hotter opaque material INTENSITY WAVELENGTH V I B G Y O R EXAMPLE GRAPH: light is removed by cloud examples: seeing stars through gas (like an atmosphere)
Kinds of Spectrum EMISSION LINE: hot transparent material in front of cool background INTENSITY WAVELENGTH V I B G Y O R EXAMPLE GRAPH: light is released by cloud examples: street lamps, fluorescent bulbs, interstellar gas clouds
Thought Question: Which of the following patterns most closely resembles the pattern of lines you saw in the spectrum? A. B. C. D.
Atoms NUCLEUS: contains almost all of an atom’s mass protons: positively-charged particles neutrons: particles with no charge ELECTRON CLOUD: electrical force keeps electrons near nucleus electrons: negatively-charged particles HYDROGENHELIUM More protons in nucleus means: stronger electrical force electrons more tightly bound to atom (on average)
Absorbing Light Electron only absorbs light with correct amount of energy to move it to an allowed distance from nucleus GROUND STATE -6 -3 ELECTRON ENERGY LEVELS: WHAT HAPPENS IN ATOM: electron moves farther from nucleus 2 UNITS OF ENERGY ABSORBED
Emitting Light Electron releases exact amount of energy needed to drop it to a smaller allowed distance from nucleus GROUND STATE -6 -3 ELECTRON ENERGY LEVELS WHAT HAPPENS IN ATOM: electron moves closer to nucleus 3 UNITS OF ENERGY RELEASED
Energy Levels allowednot allowed E1E1 E2E2 E3E3 E4E4 E=0 electrons in atoms are only allowed to: have specific amounts of total energy transition to other allowed energy levels OR off the atom absorbed light will have characteristic E and : n = 1 n = 2 n = 3 n = 4
Thought Question: The electrons in an atom can be in the energy levels shown below. If an electron is in the ground state (the level with an energy of -9 units), how many units of energy can the electron absorb and still remain attached to the atom? (Enter ALL possible correct answers as one number, then hit send.) E.8 units F.9 units G.10 units
Hydrogen: the simplest atom… Balmer lines: -13.6 eV -3.4 eV -1.5 eV -0.8 eV 0 eV E n lo = 2 n hi =3,4,5,… n lo = 1 n hi =2,3,4,…
Review Question In what order do we think the following things appeared in the solar system as it formed? A.snowflakes and dirt particles B.Earth-sized protoplanets C.rotating disk of gas D.asteroids and comets E.large cloud of gas
Review Question: The choices below describe 4 hypothetical planets. Which planet surface would you expect to be least crowded with impact craters? (Assume they orbit a star just like the Sun and are the same age as the planets in our solar system.) Size Distance from Sun Rotation Rate A. same as Venus same as Mars every 25 hours B. same as Moon same as Mars every 10 days C. same as Mars same as Earth every 10 hours D. twice Earth size same as Mercury every 6 months
Review Question The image below shows a picture of Mare Imbrium on the Moon. Put the following features in order from oldest to youngest: A) Imbrium lava, B) Sinus Iridium, C) the Apennine mountains?
Review Question If you decreased the temperature of a star, would the following A) increase, B) decrease, or C) stay the same? the intensity of the color red? the intensity of the color blue? the wavelength of the most intense color?