ASTR 1210 FINAL EXAM
no
does uranus have an internal heat source?
titan
ensity= 1.9 Surface: is NOT visible through thick clouds Pressure-at surface 1.5 bars Atmosphere: is 10x more massive than Earth's, and 10 times more extended Atmosphere is 90% nitrogen, argon, methane and various hydrogen compounds Methane and ethane exist in a liquid form on the surface Water is in an ice state Atmosphere is similar to earth in being mostly nitrogen Different from earth in having methane instead of oxygen Low temperature keeps water frozen → no water vapor in atmosphere Many organic rich compounds Surface temp is about 94K which is sufficient for ethane and methane to be in liquid form Rocks on surface are rounded due to erosion
martian canyons
equatorial canyons They are tectonic in origin, ie HUGE cracks, not due to water However, the floors of the canyons may have been eroded by water
where is martian water
Most water is lost from the planet Remainder is likely underground as ice Volcanic heat may melt ice → water flow on surface until evaporates/freezes
orbit of triton
Moves in a direction opposite neptune's rotation Irregular satellite Likely captured by a Kuiper belt object Seasons: poles take turns facing the Sun
Titan's Surface From Cassini
Narrowband infrared to see through clouds Light and dark surfaces visible Dark spots: deposition of methane
Cassinia
Plunged into Saturn's atmosphere on September 15, 2017 Orbits: 294 Titan flybys: 127 Enceladus Flybys: 23
Sky From Surface of Titan
Orange due to the attention of blue light by haze relative to red Noon sun: 10x smaller in size than the sun as seen from Earth When the sun is low in the sky, it is not visible
mars orbit
Orbit is Elliptical Polar axis is tilted 25 degrees with respect to the ecliptic plane End Result → has seasons Effects: Varying size of polar caps Dust storms Change in albedo of the Surface
Origin of Titan's atmosphere
Outgassing from icy methane and ammonia Comets Hydrogen escaped, nitrogen accumulated
mars blueberries
indentations : created in standing water "blueberries" : contain iron-rich hematite, which is formed in water
surface of mars
iron oxide, sand and dust Volcanic rocks Size distribution differs from the moon Small stones are absent, presumably due to the wind *Albedo of surface changes with the seasons Initially, this was believed to be vegetation Its actually due to the uniform blanketing of dark, underlying rocks by fine lighter colored sands
brown dwarf
is an object greater than about 13 Jupiter masses, but less than 80 Bigger than Jupiter but smaller than a star Does not fuse deuterium (proton+neutron nucleus)
spokes
particles levitated out of ring plane by forces associated with the magnetic fields
polar cap
permanent deposit of water and other frozen volatiles in the cool polar regions of the planet Initially discovered via radar mapping of Mercury. These regions have high radar reflectivity
inferior planets
planets with orbits smaller than that of the earth Both planets are observed in the morning or evening sky
Uranus and neptune:
pressure-ionized ice-oceans of hydrogen
uranus magnetic field
primarily protons and electrons from hydrogen escaping the planet's atmosphere
internal heat source of neptune
primordial heat of contraction of ice and rock Consequence: suppression of seasons due to internal heat relative to heat received by the Sun
neptune's magnetic field
protons and electrons from hydrogen escaping the planet's atmosphere and nitrogen from Triton's atmosphere
Zones
rising, cooling air out of which ammonia condenses into clouds -cool, white high-altitude clouds
irregular satellites
satellites having orbits of LARGE eccentricity, high inclination or both Captured from elsewhere
regular satellites
satellites having orbits of low eccentricity near the equatorial plane of their planet Formed in the "sub-nebula" surrounding planet
Saturn's moons
show less variation in properties than Jupiter's moons, and saturn's ring system is more extensive Smaller mass of saturn Lower temps of sub-nebula Moons are half ice half rock, but most have density range 1.1-1.4 cm3 Moons are smaller, less compression of ice than previously discussed icy moons Many moons have lunar-like crater counts
Eastern/Western Elongation
the maximum distance the inferior planets appear to get in the sky from the Sun
discovery of neptune
the motion of this plane could not be accounted for by the gravitational influence of the known planets Position of neptune was determined mathematically by Adams and Leverrier Neptune's distance from the Sun is not consistent with Bode's law
where did mars atmosphere go
this planet had a dense atmosphere intermittently as a result of major asteroid impacts which melted a significant fraction of the subsurface ice
troposphere of jovian planets
turbulent clouds due to the greenhouse effect Cold enough for water to condense
surface features of venus
1000 impact craters Sizes: 2-280 km NO LARGE CRATERS- surface doesn't date back to heavy bombardment period NO SMALL CRATERS-small impactors burn up in the thick Craters are pristine-low erosion rate
Inner Solar System Cratering
30% by comets and 70% by asteroids
mars gullies
A crater rim carved by water
discovery of uranus
By william herschel with a 7-inch telescope while mapping the sky "A curious nebulous star or perhaps a comet" Subsequent observations were used to derive a distance from the sun of 19 AU, which is consistent with Bode's law
greenhouse effect on venus
About 80% of the solar radiation is reflected back into space 10% is absorbed by atmosphere 10% reaches the ground The greenhouse effect driven by the dense atmosphere causes high surface temperatures
mercury's unique core
Appears to have a solid, silicate crust and mantle overlaying a solid, iron-sulfide outer core layer, a deeper liquid core layer, and possibly* a solid inner core
blue streaks on enceladus
Are warmer than surrounding regions, clearly indicating heat-leak
venus topography
Contrast between high and lowlands is not as dramatic as it is on Earth
saturn
At lower temperature and pressure of Saturn, liquid helium does not dissolve with liquid hydrogen Deficit of Helium relative to Hydrogen has been measured in the outer atmospheres of Saturn -which planet's source of internal heat is helium rain?
properties of saturn
Average Distance from the Sun: 1.3 light hours= 9.5 AU Orbital Period: 29.5 earth years Axis Tilt: 27 degrees (seasons) Number of Moons: about 31 Equator: is 10% wider than pole-to-pole
outflow channels on mars
Channels carved by water and running from southern highlands Connected with teardrop shaped islands where water ran into lowlands Formed later than runoff channels Associated with chaotic terrain
Properties of Mercury
Closest planet to the Sun (0.4 AU) Negligible atmosphere Heavily cratered surface Unusually large iron core-relative to its size, Mercury has the largest core Weak magnetic field
jovian satellites
Common around jovian planets Some are as large as mercury and thus are LIKE planets Some has atmospheres In 1610, Galileo discovered the 4 galilean satellites Discoveries of new satellites continue to this day reside beyond the frost line
properties of jupiter
Composition: 75% hydrogen, 24% helium +methane, ammonia, water, ice Average Distance from the Sun: 0.7 light hours, 5.2 AU Orbital Period: 11.9 Earth years Axis Tilt: degrees Number of Moons: about 61 *hydrogen and helium are colorless*
properties of uranus
Composition: 84% hydrogen, 14% helium, 2% methane Average Distance from the Sun: 2.7 light hours-19.2 AU Rotation Rise-17h magnetic field, 16h-clouds Orbital Period: 84 earth years Axis Tilt: 98 degrees Number of Moons: about 27
properties of neptune
Composition: 84% hydrogen, 14% helium, 2% methane + others Average Distance from the sun: 4.2 light hours, 30.1 AU Rotation rate: 16.8h- equitorial clouds Orbital period: 165 earth years Axis tilt: 27 degrees Number of moons: about 13
craters on venus
Crater count- 500 million year old surface Possible Speculative Explanation: about 500 million years ago, lava broke through the thick lithosphere and covered the planet The lithosphere resealed afterward
venus tectonic features
Created via tension or compression in the crust of the planet NO well-defined tectonic plates Band near equator- crustal compression
densities of uranus and neptune
Densities are high- Uranus (1.2) and Neptune (1.7) Composition cannot be the same as Jupiter Large core of rock and ice Thin outer envelopes of liquid and gaseous hydrogen No metallic hydrogen (too small)
Enceladus
Density: 1.1 cm3 Rotation pd: 1.4 days Orbital pd: 1.4 days Surface: a mixture of soft craters and complex fracture terrains Terrains are few hundred million years old Cryrovolcanism- flow of partially melted ice that mimics lava flows on silicate planets Spray of H20 and ice particles emanating from encleadus 98% of gas is water vapor, 1% is hydrogen, and the rest is carbon dioxide, methane and ammonia Geysers extend out to a distance of 3x the moon's radius with speeds up to 800 mph Tidally locked with saturn, completing 1 orbit every 32.9 hours Its orbit within saturn's e-rings Looks like IO, but Encleadus isnt forced into non-circular orbit by companion moons like IO Boulders of Ice are Visible in geologically active region
callisto
Density: 1.9 cm3 (water ice, rock) Reflectivity: 18% (no resurfacing of fresh ice) High: crater impact rate Covered with craters Material: water ice, water, earth crust, earth core Sharpness of craters is more subdued than on the moon The surface is ICE, not rock Surface is VERY old
Ganymede
Density: 1.9 g/cm3 Reflectivity: 40%, younger region 25% old region Younger region: Parallel mountains and valleys Origin: lava of liquid water resulting from density and structural changes in the ice as the moon cooled Darker, cratered regions + lighter, less cratered regions Cratering regions show it is still old
Europa
Density: 3 g cm/-3 Primarily rock with water ice Reflectivity: 70% Similar to Earth: surface mostly covered in water and ice Streaks and ridges are cracks in icy surface Ridges may result from material being squeezed up from below Purity of surface→ resurfacing process No evidence of impacts Source of energy for resurfacing: tidal heating by jupiter
Io
Density: 3.3 g cm3 THIN atmosphere of sulfur dioxide (sulfur and oxygen from Io are major contributors to charged particles in Jupiter's atmosphere) NO impact craters → surface is young White surface is sulfur dioxide Other regions: hydrogen sulfide, sulfur, sodium Surface is so young because of volcanoes Violent and short lived: dark red deposits with sulfur as primary ejecta Long lived: white deposits of sulfur oxide Why sulfur? 100,000 tons of material ejected each second Could cover entire surface to a depth of 10s of meters in 1 million years 10 tons per second Volatiles such as water and carbon dioxide have long been lost
venus vs earth
Diameter is 12,104-smaller than earth Density is 5.3 g/cm3- smaller than earth Has a major atmosphere (like earth) Moons 0- earth has 1 Rotation period is -243 earth days Orbital period is 224 earth days Has no plate tectonics-earth has them Has NO oceans
tharsis bulge on mars
Elevated region containing large shield volcanoes Few craters Such a tectonic uplifting is a result of association with volcanoes, not compression Underlying hotspot causes ground to rise Eruptions result in shield volcanoes Olympus mons Crater counts indicate that the youngest lava flow was 100 million years ago Olympus mons may thus still be active
difficulties with sending probes to jovian planets
Energy source: solar panels + internal radioactive generators needed Distance from earth: autonomous Destruction of spacecraft-asteroids, rocks, etc. Trajectory: gravity assisted
Evidence of Active Volcanoes on Venus
Evidence 1: rise and fall of sulfur dioxide in upper atmosphere: injection from volcanoes? Evidence 2: transient features changing in brightness and temperature Evidence 3: dark regions indicative of darker, younger, residue
Flood Volcanism on mercury
Flood volcanism plains cover 6% of the surface Flood volcanism plains were formed after the impact basin Large-scale volcanism occurred after the period of heavy bombardment Mosaic of western side of planet showing lava-filled craters and plains
Air Circulation of Uranus:
Follows rotation, not hadley cells, similar to neptune Wind speed highest NEAR POLES NOT EQUATOR If poles continuously heated, the winds should increase towards the equator neptune shows similar rotational structure Temperature is nearly the same at both poles We have no clue why any of this is observed
internal structure of jupiter
Gaseous hydrogen (125 K) , liquid hydrogen (2,000K) , metallic hydrogen (5,000K), rock, metal and hydrogen compounds (20,000 K) Notes: the behavior of hydrogen and helium at high temperatures and pressures is NOT well understood
Energy for Io via tidal forces:
Gravitational pull- of Europa and ganymede keep Io from achieving circular orbit Io experiences tidal torques as it approaches and recedes from Jupiter Jupiter is slowing down as a result of this interaction: Io, Europa and Ganymede are being pushed outward
storms on neptune
Great dark spot Clouds: ice crystals (cirrus clouds) of methane Banding presently less prominent on Uranus due to axis tilt-pole continuously heated, producing extra haze High elevation ice clouds
atmosphere of enceladus
Has been detected via an occultation of a star Note the asymmetry in the light curve
atmospheric structure of mars
Height of the Troposphere is low relative to Olympus Mons Note the height of the dust storms Troposphere disappears at night due to the thin atmosphere and lack of bodies of water
triton terrains
Higher latitudes-rough terrain crossed by long grooves Latitudes above equator: smooth, uniform material with uniform tint Southern hemisphere: flat plains covered with dark spots and wind streaks from thin atmosphere Active geysers and plumes in southern hemispheres Activity may be induced by seasonal heating by the sun Nitrogen with small amounts of methane Driven by volcanic activity due to seasonal heating by the sun
Venus clouds
Highly Reflective (75%) Cloud Temperature (-35 C) Upper Atmosphere: clouds rotate around planet in FOUR days due to Rotation of planet Thin upper atmosphere Heating by solar radiation Lower Atmosphere: Wind speed: 0-2 m/s Coriolis is negligible-slow rotation of planet Hadley Cells-air traveling via convection from equator to poles
Appended formation of jovian planets
Ice and rock core are built mass = 10 earth masses Hydrogen and helium from surrounding solar nebula form satellites Uranus and neptune are less massive because Particles spread out in solar nebulae and thus accretion was slower Jupiter has a density similar to Uranus because Very massive planets compress their interiors to high densities
jovian planetary interiors
Ice-rich planetesimals make up 3% ad 10% of jupiter and saturn's mass, respectively They make up ⅔ of Uranus and Neptune's mass--cores are a mixture of ice, rock and metal Jupiter and saturn have cores of rock, metal and hydrogen compounds, visible clouds, gaseous hydrogen, liquid hydrogen, metallic hydrogen Uranus and neptune have cores of water and rock, and exteriors of gaseous hydrogen, visible clouds
Titan surface
Liquid methane Frozen water ice Hydrocarbon particles settling out of atmosphere
surface of mercury
Lots of Impact Craters over much of the surface= old surface** Lower crater density than some lunar regions Resurfacing by lava flows Small lava plains Mercury was probably volcanically active when it was young Maybe STILL vocanically active
jovian planets
Low Density Small "core"/ atmosphere radio Rings Many natural satellites
magnetic fields of jovian planets
Magnetic poles are not aligned with rotational poles are off-axis Cause Pressure ionized ice surrounding rocky core Oceans of hydrogen
origin of outflow channels on mars
Melting of subsurface ice by deep seated volcanic activity Shifting of underground water due to creation of Tharsis uplift
tidal effects of mercury
Mercury year= 88 earth days Mercury day= 59 earth days Orbit is eccentric Rotation period minimizes the tidal dissipation near perihelion
surface of triton
Methane ice and nitrogen Pinkish color: organic compounds produces via chemical reactions of surface Very small impact crater density YOUNG surface
'Oumuamua
Newton: Ellipses (and circles) are only one kind of orbit Ellipses are bound orbits Parabolic and hyperbolic orbits are unbound Circles, ellipses, parabolas and hyperbolas ae conic sections For all orbits, objects move faster when closer to the object being orbited *this object is not bound to the solar system. It formed elsewhere in the galaxy Is the first interstellar intruder observed in the solar system The albedo is about 0.1, the size is estimated to be 150m x 45 m Small, sub km object Has very blue optical colors, doesnt have red optical colors similar to kuiper belt objects Doesnt have a coma, its sublimation rate is below the detection threshold
properties of mars
Non-circular orbit Atmosphere of CO2 (95%) Greenhouse effect Dust storms
map of martian surface
North→ primarily lowlands, relatively low crater density, younger surface South→ primarily highlands, relatively high crater density, older surface
surface of mercury
Ratio of potassium (LOW vaporization temperature) to thorium, which is a measure of volatile abundance, is like other terrestrial planets Ratio of potassium is higher than the moon-potassium was lost during the giant impact that formed the moon TEN TIMES the sulfur abundance of other terrestrial planets, more evidence of volatile rich environment Very low iron relative to other terrestrial planets Mercury formed in water-free environment rich in comet-dust like material
rotation of venus
Retrograde rotation Long sidereal day: -243 earth days Solar day: -117 earth days
mercury hollows
Rimless, hollowed out depressions on the surface, similar to appearance of swiss cheese Highly reflective No equivalent features on the moon the interior of Mercury contains higher abundances of volatiles than previously expected
equatorial bulges on jovian planets
Rotation Rates: 10-17 hours Gravity makes planets bulge at the equator Jupiter and Saturn are about as large as planets can be
Tilt of Uranus Rotational Axis
Seasons last for 20 years Cause of tilt: glancing collision with planet
properties of venus
Second planet from the sun THICK atmosphere composed primarily of CO2 High surface temperature Clouds of sulfuric acid Extreme greenhouse heating: 800K at the surface
olympus monts on mars
Shield volcano: volcanoes which build up massive domes with gentle slopes from an eruption of fluid basaltic lava Summit Crater: produced by the collapse of the surface when the underground pressure of the magma subsides
mars mountains
Size of mountains are limited by the planet's surface gravity and the crustal rock strength -can have high mountains because its surface gravity is low
volcanic hot spots on IO
Some in the form of lava lakes To the left: Loki Patera Lake of liquid sulfur with a raft of solid sulfur inside
Jupiter's great red spot
Storm that has persisted for at least 300 years Size: twice as wide as the earth Why are storms so long-lived? No solid surface to sap away energy (as happens on the earth)
triton
Surface temperature: 38K One of the COLDEST surfaces in the solar system Nitrogen condensed as frost on the surface
where did mars dense atmosphere go
The molten core of this planet cooled off, shutting off the planet's magnetosphere Without the magnetosphere, the solar wind could effectively ionize the upper atmosphere and entrain the ionized particles in the solar magnetic field
crater rates on mars
The proximity of this planet to the asteroid belt results in higher cratering rates than most terrestrial objects
why venus and earth have different atmospheric content
The water in the Earth's atmosphere formed in the oceans The CO2 in Earth's atmosphere dissolved in the water and formed rocks Nitrogen is the third most common gas expelled via volcanism The O2 abundance in the earth's atmosphere is due to plant life
mercurys tilt
Tilt of rotational axis with respect to the ecliptic plane is 0 degrees, thus polar regions receive little sunlight
why venus can hold dense atmosphere
Venus is 8x more massive than mars, and thus can more effectively hold its dense atmosphere via gravity
models of mercury
Violent young sun baked the primordial dust that would become mercury Outbursts from the sun blasted mercury, evaporating away enough rock to reduce it to its present size Mercury was struck by a large object which stripped away much of its rock
dust storms on mars
When: Southern Hemisphere-summer Cause: strong convection sucking hot air to high elevation, resulting in cool air rushes ground-ward
enceladus interior
Wobbles in orbit Motion is consistent with a model where water is sloshing around below its icy surface
origin of rings
a large moon strayed too close to its planet as a result of an impact Problem: such an unlikely event would have to have happened to all of the Jovian planets
impact basins on Mars
depth has been affected by erosion, or crust stabilization, since period of intense bombardment
gaps
are present in the rings. They are created by gap moons that nudge particles out of particular orbits
Outer Solar System cratering
comets only
surface features of venus
coronae Circular/ Oval Features 100s-1000s km across Characterized by concentric and radial tectonic patterns and often by associated volcanic eruptions What are they? Failed hot spots Developing hot spots
Gravitational Effect of Planet:
cratering should occur at a higher rate with larger impacts for moons near planet
water on mars
erosion features present Some features carved by water Source: rain? Water features this planet was wet in the past Running water on this planet requires thicker, warmer atmosphere Crater Count: 2-3 billion years old. This sets a limit on when water flowed through this riverbed Found in high elevation Regions with high crater density Thus, they pre-date northern plains -Running water contributes to erosion
belts
falling air depleted in clouds, allows clouds to be seen -warm, red, low-altitude clouds
mercury's rotation
for hundreds of years it was thought to rotate synchronously, so that it always kept face to the Sun, just as the moon always keeps one face to the Earth. Its actual rotation, however, causes it turn exactly one and a half times each time it goes around the Sun, so that it turns one side toward the Sun in orbit, and the other side toward the Sun in the next orbit, making the DAY on Mercury twice as long as the YEAR
Caloris Basin
largest structure on Mercury (1000 km) created by an impact with an asteroid. The circumference of Mercury is 15400 km. A similar feature is seen on the western edge of the Moon-Mare Orientale The impact that resulted in the Caloris Basin generated compression on the surface of Mercury
Synchronous rotation
leading side of the moon receives more craters than the trailing side
jupiter's rings
less prominent than saturn's Why? Smaller particles
jupiter and saturn source of magnetic field
metallic hydrogen (motion of free electrons)
composition rings
mixture of rocks of varying sizes comprised mostly of water ice (high albedo) Dimensions of saturn's rings 270,000km x 10s of meters Roche zone: tidal forces-binding gravitational forces Note: smaller rocks are held together by gravitational forces and electrostatic forces and thus can survive
earth
neptune has an axis tilt similar to___
rings of neptune
small particles Rings were seen from Earth to be incomplete rings Voyager 2 detected dust sheets between rings of both neptune and Uranus
impact craters on mars
smooth ejecta blankets (fluidized ejecta) caused by ice vaporized by impact
saturn magnetic field
solar wind
jupiter magnetic field
solar wind and volcanically active Io
origin of rings
the ring particles originate from small moonlets which are being ground up by impacts with dust sized particles, or through occasional impacts with larger objects Majority of the ring particles are young and reflective Continuous replenishment from moonlets Consequence: the ring may look very different in future
source of internal heat from jupiter
the slow contraction of the planet Gravitational potential energy→ kinetic energy→ thermal energy
origin of rings
they formed from leftover chunks of rocks and ice that condensed into a disk of gas around the planet Problem: these chunks would have been ground down in size by impacts with small dust particles that orbit the sun. The ground up remains would have lost angular momentum from pressure from sunlight, and they gradually would have spiraled into the planet
jupiter and saturn
which planets radiate twice as much heat as they receive from the sun
origin of rings- roche zone
within 2-3 planetary radii of any planet, the tidal forces on an object are comparable to the force of gravity holding it together Tidal forces could, in principle, rip a moon apart, or keep a moon from forming
mars moons
wo moons (phobos and deimos) Probably captured from the asteroid belt The moons are irregular in shape