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(Wien’s Law):Wavelength gets shorter as temp gets higher ● hotter=more blue ● cooler=more red ymax= constant/temp (constant= 2.9 x 10^6) 1. The observed electromagnetic spectrum from a star has a peak at 500 nm. What is its surface temperature in degrees Kelvin? 500nm = 2.9x10^6/T 500T= 2.9x10^6 T= 5800 2. The observed electro magnetic spec from a star has a peak at 580 nm. What is its surface temp in degrees Kelvin? 580= 2.9x10^6/T 580T= 2.9x10^6 T= 5000 Stefan-Boltzmann law ● energy= sum of the rates of emission at all wavelengths ● A hot object radiates more total energy than a cool one of the same size E=qT^4 1. How many times more energy is emitted per unit of time and unit of surface area of a star with surface temperature 4000 K as compared to that emitted from the same-size area and same amount of time of a different star with surface temperature 8000 K? Because it doubled, it is 16 times as large, but let's do the math anyway.8000/4000 = 2 2^4 = 16 2. How many times more energy is emitted per unit of time and unit of surface area of a star with surface temperature 10000 K as compared to that emitted from the same-size area and same amount of time of a different star with surface temperature 5000 K? 10000-5000= 2 2^4= 16 The inverse square law (Chapter 6, page 103, Fig, 6.3). How many times lower would the intensity of light from a given star become if the star was 3 times farther away? ● 9 times lower; 4 times lower if it was twice as far away. Albedo The albedo of a planet is the fraction of energy that is reflected by the whole planet, including atmosphere and surface What is the Coriolis effect? ● Rotation causes the Earth to have an oblate shape. The Coriolis effect causes moving objects and air masses to appear to be deflected from straight line paths. It is responsible for spiral like circulation patterns in the atmosphere and oceans. ● Appears to curve the paths of moving objects, winds and water currents to the right in the northern hemisphere and to the left in the southern hemisphere. What is the structure of Earth’s interior and how do we know about it? ● The density of the earth’s interior must be even greater than 5500 kg/m^3 ● The interior pressure of the earth is caused by the weight of the overlying matter, just as the pressure in the earth’s atmosphere is caused by the weight of overlying air. ● Because heat flows outward through the Earth’s surface, the interior must be hotter than the surface. Measurements in mines show that as you move inward, the temp increases by about 20 to 30 K. ● Direct evidence that temp continues to increase below the depth of the deepest drillings comes from volcanos. The Earth’s magnetic field and its reversal. ● Earth’s magnetic field is result of a dynamo, in which the rotation of the Earth causes electric currents to flow in liquid, electrically conducting portions of the planet's interior. ● The earth’s dynamo model requires that somewhere within the earth's surface there must be large scale fluid motions of conducting (probably metallic) material.● REVERSAL: dynamo model is supported by evidence of changes in the earth’s magnetic field. Most dramatic example are reversals of the direction of the magnetic field on time-scales of hundreds of thousands of years or less. ● Evidence for reversal changes is found in the alignment of magnetic materials in lava beds. ● Last reversal was as recently as 30,000 years ago Earth’s magnetic axis ● Inclined about 11 degrees Earthquakes ● Earthquakes produce seismic waves, which give us info about the composition and density at different depths of earth. ● The speed of the waves show this Internal structure of earth ● The three major layers of the earth are the crust, the mantle, and the core. ● The crust, made of light rock, sits atop the denser rock of the mantle ● The core is mostly metal ● The upper 70 km of the crust and mantle make up the rigid lithosphere. ● Under the lithosphere is the asthenosphere, a plastic, partially melted zone about 200 km thick. What is seafloor spreading? ● Seafloor spreading: The ridges on the seafloor occur where the ocean floor cracks apart. Magma from the interior oozes out of the crack to form a new ocean bottom, which then spreads apart as the process continues. ● The continents, frozen into sections of the lithosphere called plates, are carried along as the plates are pushes by seafloor spreading. What kind of plate motions do exist? ● Zone of divergence: plates separate ● Zone of convergence: plates collide ● Subduction: when plates collide, the overridden plate is destroyed by being driven down into the mantle and melted ● Transform Fault: plates slip past each other Layers of Earth’s atmosphere. (from lowest alt to highest) 1) troposphere ● Most gas is located here ● Lower troposphere: heating absorption and infrared solar radiation absorption ● convection= clouds and turbulence2) stratosphere ● Temp increases w altitude bc of heating due to solar radiation 3) mesosphere ● Temp falls w increasing height 4) thermosphere ● Temp climbs steadily bc of ultraviolet sunlight What are the Van Allen belts. ● Form when High energy particles from solar wind are trapped in magnetosphere ● The earth’s magnetic field traps charged particles in belts or shells that surround earth How did the earth’s atmosphere, earth’s interior, and oceans form, and how did they evolve from primeval time? ● Originally Earth’s interior and exterior were nearly uniform until differentiation when the denser objects were pulled to the core and the lighter objects began to form the crust. ● Oceans: Water in primitive earth was chemically locked up minerals, then water gradually was released from the molten interior and reached the surface along w lava ● At the surface water entered the atmosphere as steam ● ATMOSPHERE: primeval atmosphere almost completely lost as a result of violet impacts between earth and large infalling bodies ● Present atmosphere is called secondary atmosphere which gradually developed as gas was released from the interior during volcanic eruptions (outgassing) ● Outgassed carbon dioxide dissolved in oceans ● Oxygen due to photosynthesis Pg 175 Lunar eclipses. What causes them, and why don’t we see them as often as once a month? ● “Because the Moon’s orbit is inclined by about 5 degrees relative to the ecliptic, the Moon is usually above or below the ecliptic when it is new or full. At least twice a year there are periods when the Moon, in its new or full phase, is near a node and eclipses can occur.” pg 189 ● Hence, lunar and solar eclipses occur when the moon is near/on a node and therefore directly in view of the sun from our perspective. ● Eclipses involving the earth and moon occur when one of the two enters the shadow of the other... so the earth moon and sun have to be in an almost perfect alignment ● Moon needs to be near the ecliptic plane What is the moon’s synchronous rotation?● The moon rotates and revolves in the same length of time, the sidereal month (27.32 days). ● This synchronous rotation keeps the same face of the moon turned towards the earth. ● Proof shown in tidal interactions Features of the moon surface. ● Craters are the dominant features of the lunar surface ● Regolith: layer of surface debris Moon’s size and density relative to those of the earth. ● Moon’s diameter is found to be 3476 hm, 27% as large as the earth. ● Ave density of the moon is about the same as that of the earth’s crustal rocks and is consistent with the small size of the moon’s metallic core. ● Seismic measurements have shown that the moon’s crust and lithosphere are both much thicker than that of the earth ● Compared with earth, the moon’s interior is very inactive. Compare the atmospheres of Moon, Mercury and Venus and Mars. What are their similarities and what are their differences? ● Moon atmosphere: ○ almost no atmosphere (same w mercury) ○ Helium neon argon and hydrogen ○ Atmosphere poorly insulates it so temps drop after sunset and swiftly rise after sunrise ○ The moon’s atmosphere is extremely tenuous ○ Consists of temporarily trapped solar wind gases and gases released by radioactive decays in surface rocks. ● Mercury ○ Has almost no atmosphere (same w moon) ○ Sodium oxygen helium potassium and hydrogen ○ Mercury has a very tenuous atmosphere which probably consists of gases trapped from the solar wind or produced when meteoroids vaporized as they struck mercury’s surface. ○ The uneroded condition of old craters shows that mercury never had a thick atmosphere. ● Venus ○ Venus is hotter and denser than earth ○ Has an entirely different chemical composition than earth. Carbon dioxide ○ Very high surface temp ○ Twice as much sunlight strikes venus each second than earth ○ Earth absorbs more solar energy● Mars ○ Atmospheric pressure is less than 1% of earth's ○ Although Mars’s atmosphere is much cooler and thinner than Venus, they are quote similar in chemical makeup ■ Carbon dioxide makes of 95% ○ Atmosphere unable to insulate ○ Absorbs very little sunlight ■ Very large daily and seasonal temperature fluctuations ○ Dust storms ● Moon, Mercury, and Mars: have difficulty retaining even heavy gases Compare the densities of the Moon to that of Mercury and that of the Earth. Moon compared to earth: ● Ave density of the moon is about the same as that of the earth’s crustal rocks and is consistent with the small size of the moon’s metallic core. ● Seismic measurements have shown that the moon’s crust and lithosphere are both much thicker than that of the earth ● Compared with earth, the moon’s interior is very inactive. Moon compared to Mercury: Bc Merc’s average density is nearly as large as the Earth’s and the average density of the moon is 3340 so merc has greater density than the moon Mercury compared to earth: ● Merc’s average density is nearly as large as the Earth’s ● Bc the material in mercury’s interior is less compressed than that of earth, Mercury must contain a large portion of iron or other heavy elements in order to be so dense ● Mercury has a magnetic field, suggesting that the planet has a liquid metallic core. ● The core reaches about ¾ of the way to mercury’s surface. Main characteristic of Mercury’s rotation and orbit around the Sun. ● Its orbit is more elliptical than that of any other planet Main characteristic of Venus’s rotation and orbit around the Sun. ● Venus is the only planet to rotate clockwise but still orbit the sun counter-clockwise. A day on Venus is 116.8 days on Earth (I’m sure all we need to know is it’s super slow). Compare the conditions of surface temperature, pressure, composition of atmosphere and of clouds between Earth, Mercury and Venus and Mars. ● Earth: ● Mercury:○ Surface temp: Hot during day and cold during night bc there is no atmosphere to retain heat ○ Pressure? ○ Main atmospheric gasses: Na, O, He ○ Clouds: none p much ● Venus: ○ Surface temp: remarkably warm (very high) due to greenhouse effect ○ Twice as much sunlight strikes venus each second than earth ○ Earth absorbs more solar energy ○ Pressure: extremely large at 92 atm ○ Comp of atmosphere: primarily carbon dioxide ○ Clouds: The clouds of Venus are made of droplets of concentrated sulfuric acid. A thick layer of clouds completely seals the surface of venus. Enough sunlight penetrates the clouds to make the surface as bright as the Earth on a cloudy day. ○ Compared to earth, venus’s clouds are not very dense ○ Wind ● Mars ○ Pressure: atmospheric pressure fluctuated as carbon dioxide is trapped in and then released from the Martian polar caps ■ Lowest in the winter and summer ○ Clouds: there is always hazy dust, but clouds are rare on mars ■ There is fog. most likely morning fog which suggests that the surface layers contain frozen water ○ Weather: monotonous bc mars has no surface water and little water vapor ○ DUST What are the main features of the surface of Mercury and what is their origin? ● CRATERS: Like the moon, the surface of Merc is dominated by impact craters ● Merc has a larger gravity than the moon, so material ejected from craters lie closer to the crater than is the case for the moon. ● Old impacts are preserved better on merc than the moon ● Has badly degraded basins that appear to be the remnants of an ancient heavily cratered surface ● PLAINS ● cliffs? Venus and Earth: ● Mass radius and density of venus are all slightly smaller than those of the earth. ● Earth’s orbital; distance is closer to venus than any other planet ● Venus and Earth’s atmosphere is very different ○ Venus is hotter and denser ○ Has an entirely different chemical composition ● Twice as much sunlight strikes Venus each second as strikes the Earth● Venus’s high surface temp is due to the greenhouse effect ● The climates of venus and earth probably were similar at first, However, the somewhat higher temp of venus resulted in more water vapor in its atmosphere, which inhibited the cooling of venus by infrared radiation and quickly led to a much hotter climate. What are the main features of the surface of Venus and what is their origin? ● There are fewer than 1000 impact craters on venus ● Small meteoroids are destroyed by the thick atmosphere before they reach the surface ● Venus appears to have been resurfaced by lava flows about half a billion years ago What are the main features of the surface of Mars and what is their origin? ● “Two faced planet” one side looks densely cratered (ancient craters), the other seems sparsely cratered. ● Sparsely face resembles the lunar maria ● Ejected material appears to have flowed away from craters which suggests that there may be substance ice or water on mars ● Plate tectonics existed What is the role of volcanic activity on Mercury, Venus and Mars? ● Venus: ○ Main type of volcano are shield volcanoes ○ More evidence of volcanic activity than any other planet ○ Arachnoids and coronae ○ No plate motion ● Mars: ○ Extensive volcanic flows, particularly in the northern hemisphere, have obliterated the ancient cratered terrain ○ The largest known volcanoes in the solar system are found in the Tharsis Region, a continent-sized bulge on Mars. These large volcanos show mars’s crust must be stable and the lithosphere must be thick. ○ Volcanic activity was widespread until about 2.5 billion years ago. It is now more restricted Compare the composition of the interior of Mercury, Venus, Earth, and Mars. ● Venus: ○ The similarity of venus to earth implies that they formed from similar materials and have similar internal structures. Venus is thought to have a liquid metal core but no measurable magnetic field (bc it moves so slowly) ● MERC: ○ Merc’s average density is nearly as large as the Earth’s○ MERC: Bc the material in mercury’s interior is less compressed than that of earth, Mercury must contain a large portion of iron or other heavy elements in order to be so dense ○ MERC: Mercury has a magnetic field, suggesting that the planet has a liquid metallic core. Weaker than earth ○ MERC: The core reaches about ¾ of the way to mercury’s surface. ● Mars ○ Stable crust ○ Thick lithosphere ○ Ave density is 3940 (larger than earth’s)= little compression ■ Shows mars has a considerable amount of iron and other heavy materials ○ Mars’s core is made mostly of iron and nickel (maybe sulfur???) ○ The outer part of the core is liquid ○ Amount of iron on mars continues a general trend of lower iron to rock ratios with increasing distance from the sun What are the main chemical elements which can be found on Jupiter and Saturn? ● Main atmospheric gases as well as general elemental make-up on both are hydrogen and helium. What is the structure of the interior of Jupiter and Saturn? ● Jupiter ○ Tremendous size and internal pressures ○ Low density ■ Cannot be made of rocks and metals like earth and other planets ○ Hydrogen and helium ● Saturn: ○ Diameter more than 9x the size of earth ○ Mas 95x as great as earth ○ Low density ■ Float in water (if possible) ■ Light elements must dominate the chemical makeup ○ Hydrogen and helium ● Interiors for both: ○ From surface to core: liquid molecular hydrogen, metallic hydrogen, rocky metallic core ○ Pressures and temps in deep interior must be very high ○ Potential rocky cores ○ Contains some rock , metal, and ice prob concentrated in center ○ Self luminous What is the origin and structure of the belts of Jupiter? Zones and Belts – banded appearance from convection in atmosphere. –Zones -- bright bands, warmer material rising(?). – Belts -- Dark bands, cool material sinking(?). Rising and falling convection currents in the atmospheres are stretched into bands by rapid rotation cause em What is the Great Red Spot and how it was created? ● The Great Red Spot is an atmospheric storm in Jupiter’s southern hemisphere. Its size and color can vary and it rotates counterclockwise which indicates that it is high-pressure and gas flows outward. ● In light of the new, very recent red spots on Jupiter, it is safe to predict that it was created by merging white oval-clouds in the atmosphere that came together and got larger and redder. - pg 274 What are the main features of the rings of Saturn? ● Rings are very flat and thin. ● Made up of very many individually orbiting particles that range from 1 cm to tens of meters in diameter. Small particles outnumber large ones, and most of the particles are bits of water ice or rocks covered by ice. What is the structure of Jupiter’s atmosphere? ● Hydrogen molecules and helium atoms make up almost 99.9% of Jupiter’s atmospheric gases on a 4kg:1kg ratio. Has far more helium than Saturn. ● The cloud layers from the surface upward are: water ice, ammonium hydrosulfide ice, ammonia ice. Atmosphere of Uranus Blue-green/blue due to methane. • Cold makes haze, hiding detailed features below. • Very featureless More bout ur anus jajaja Uranus is tilted on its side (98°) – Pole almost points towards Sun. – Causes drastic seasons. – Why on its side? Possible collision. Atmosphere of Neptune Blue due to methane. • Cold makes haze, hiding detailed features below. • More structure in Atmosphere. • Has storm systems • Great Dark Spot -Banded structure suggests belts and zones something like Jupiter.Nep and Ur vs Jup and Sat . Uranus and Neptune have proportionately more heavy gases like water and methane. Jupiter, saturn, uranus, and neptune: retain hydrogen the lightest most rapidly moving gas Moon Mercury and Mars: have difficulty retaining even heavy gases Earth and venus:able to retain gases as heavy as nitrogen and oxygen but not hydrogen (present in tiny amounts) Asteroid, meteorites and comets. ● Meteor: bright streak of light produced when a piece of interplanetary debris moves rapidly through the Earth’s atmosphere. ● Meteoroid: The piece of debris ● Fireball: gross ass liquor or a big enough mererid to produce a spectacularly light meteor ● Meteorite: the part of the meteoroid that reaches the ground ● Meteor showers (increase in rate meteors are observed) are very predictable bc they happen on the same day each year ● Radiant: the spot in the sky where the meteors seem to originate ● Micrometeorites: small meters that are slowed down without becoming hot enough to vaporize. Fragile and look like dust balls ● Asteroids: the multitude of rocky bodies that orbit the sun within the planetary system and that range from a few kilometers in diameter up to nearly a thousand kilometer in diameter. Also called minor planets. ● Asteroids have eccentric orbits more inclined to the ecliptic plane ● comet : Small icy body in orbit about the sun. What is the asteroid belt, how we believe it was formed and where it is located? ● 2.1 and 3.3 AU from the sun ● The overwhelming majority of known asteroids are in the asteroid belt ● Asteroids are widely spread out ● lie in a vast ring between the orbits of Mars and Jupiter??? ● IDK HOW IT WAS FORMED What are the size distribution of the asteroids. ● range from a few kilometers in diameter up to nearly a thousand kilometer in diameter.????? What is the structure of a comet? It is a spectacular sight with a bright head and tails stretching across the sky.● A comet consists of only a nucleus, a loosely packed chunk of water and ice, other ices, and dust. The warmth of sunlight, however, drives gas and dust from the nucleus. These form the coma, the dust tail, and the plasma tail of the comet ● Nucleus: only part of comet present at all times ● Coma: a ball of outflowing gas which can be a million kilometers in diameter (much bigger than the nucleus) Appears bright bc of a combination of emission from the gas and sunlight reflected by the dust. ● Tails: ○ Dust tail and plasma tail ○ Dust: yellow and much broader than the plasma tail. Appear to be curving arcs ○ Plasma: Blue and often much longer than the dust tail. Very straight ○ Both point away from the sun. So they sometimes follow the nucleus or precede it Where are comets coming from? ● Comets probably formed at the outer edge of the planetary system, near neptune. Many of them may still exist there as the Kuiper Belt. There may be some very large comet nuclei of which chiron and pluto may be examples. How do we use the atomic emission and absorption spectra to find the composition of a star? ● When an atom absorbs a photon, the energy carried by the photon causes an electron to jump to a higher energy level. When an atom emits a photon, one of its electrons jumps to a lower energy level. The absorption and emission of radiation by atoms produces dark-line and bright line spectra. A given element or compound can only absorb or emit photons of certain energies. Thus the pattern of dark or bright lines in the spectrum of an element or compound is characteristic of that element. ● Krichhoff’s laws ○ A hot solid, liquid, or dense gas produces a continuous spectrum in which emission appears at all wavelengths. ○ A thin gas, seen against a cooler background, produces a bright-line, or EMISSION LINE, spectrum. An emission line spectrum consists of narrow, bright regions separated by dark regions. ○ A thin gas in front of a hotter source of continuous radiation produces a dark line, or ABSORPTION LINE spectrum. An absorption line spectrum looks the same as a continuous spectrum except that there are narrow wavelength regions in which the radiation is diminished or absent. ■ The spectra of the sun and most stars are examples of absorption line spectra. This shows that continuous radiation from interstellar layers passes through relatively cool gas in the outermost layers of the star before it reaches us. How do we determine the rotation period of a star?Because of the doppler effect (source and observer moving closer together = shorter wavelength/blue shift/left; source and observer moving apart = longer wavelength/red shift/right), the wavelengths of the spectral lines of a star depend on how rapidly the star is moving toward or away from the earth. The doppler shift of a star's spectral lines makes it possible to determine the speed with which the star moves toward or away from us and possibly how fast the star rotates How do we determine the distance to a star using Stellar Parallax? ● “The distance to a star can be found by measuring its parallax, the apparent change in the direction of the star that results from viewing it from different places on the earth’s orbit around the sun. All stellar parallaxes are smaller than 1 second of arc. The distance to a star, measured in parsecs, is the reciprocal of its parallax, measured in arcseconds D (parsec) = 1/p(“) 1. Suppose there were a star with a parallax of 0.2 second of arc. p=.2 So d=1/.2=5 pc What is an H-R diagram and what information does it give us? ● An H-r diagram is a plot of the luminosities of stars against their temperatures. Most stars are clustered within four areas of an H-R diagram. The regions within which most stars are clustered represent long-lived evolutionary stages for stars. ● Most significant feature is that the stars do not uniformly fit in. ● Significance is that it important info about the evolution of stars ● Main sequence: runs diagonally from hot, luminous stars, to cool, dim stars. Contains most stars ● Giant region: contains cool, luminous stars. ● Supergiant region: the most luminous stars that lie at the top of the H-R diagram. ● White dwarf: contains hot but dim stars located in the lower left QUESTIONS: Which of the following is a consequence of the fact that the rotation and revolution periods of the moon are the same (synchronous rotation)? A. We always see the same side of the moon B. The moon can never be seen from one of the earth’s hemispheres C. All lunar phases can be seen from the earth’s surface D. There are 12 months in a year The craters on the moon and on mercury surfaces are due toa. Volcanic activity b. Collisions with meteorites and asteroids c. From tectonic activity d. None of the above Which of the following best describes the rotation of Venus? ● Slow and in opposite direction of other planets The highest mountain on Mars is? ● Olympus Mons, which rises 24 km above the surrounding plains, is broader than the entire region covered by the main islands of the Hawaiian chain. - pg 239 The Great Red Spot is present on Jupiter since ● For at least 300 years The interior of Jupiter and Saturn, going from surface to the center, contains ○ liquid molecular hydrogen, metallic hydrogen, rocky metallic core The main two elements on the planets of the outer solar system are Hydrogen and helium Water on earth is due to Volcanos Metallic hydrogen exists in large amounts a. In the interior of mercury b. In the interior of jupiter c. In the interior of mars d. In the interior of the moon Observed electromagnetic spectrum from a star has a peak at 580 nm what is its surface tmp in degrees kelvin ● 4000k ● 1000k ● 5000k ● 3000k Wien’s law!!^ max of wavelength is 2.9 x 10 ^6 (nm k) over T How many times more energy is emitted per unit of time and unit of surface area of a star with surface temp 10,000k as compared to that emitted from the same size area and same amount of time of a different star with surface temp 5,000k? ● 2 times● 4 times ● 8 times ● 16 times Temp 1 over Temp 2 to the fourth 10,000 over 5,000 to the fourth 2 to the fourth Direction of Earth’s magnetic field changes every few hundred thousand years (?) Layer sequence of the Earth: crust, mantle, liquid core, solid core We know Earth’s interior because seismic waves and volcanic rock (?) Evidence of reversal of Earth’s magnetic field Evidence for reversal changes is found in the alignment of magnetic materials in lava beds.