Download Mercury = Hermes Mythology

Mercury = Hermes Mythology
• Planet Mercury, Element,
Mercredi
• God of Commerce, Messenger
God, guide to Hades
• Winged sandals and staff
Mercury’s Orbit
• Mercury never seen more than
28° from the sun
• Revolves/orbits 0.4 AU from
sun in 88 days
• Rotates in 59 days (radar)
• 3 Rotations to 2 revolutions
• Resonance
Mercury Differentiation
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Small mass high temperature=no air
Most dense planet except Earth
Iron core – 75% of radius
Tiny magnetic field – slow rotation?
Liquid core?
• Melted - heat of formation & decay
of radioactive elements
Impact Craters
• Heavy bombardment cratered
surface
• Strange dark rimmed crater
• Crater with gullies run to/from
Intercrater Plains
• More craters than the Lunar
Maria 3.5 Billion, but less
than Highlands 4.5 Billion
years
Caloris Basin
• Giant impact creates ringed
basin
• Later flooded by lava
• Jumbled terrain on opposite
hemisphere of planet
• Mariner 10&MESSENGER
Volcanism on Mercury
• Volcanic vent is kidney shaped depression
Lobate Scarps
• When Mercury cooled it shrunk & surface wrinkles formed
• Which pass through a previously (109 years) existing crater
• Smooth plains and intercrater plains (similar to maria) not
saturated with craters so must be younger than other areas
Messenger on its way
back to Mercury
• Launched Aug04; loops around
sun 15 times, Earth once, Venus
twice and Mercury 3 times
• Will finally orbit in 2011
Rotation of the Moon
• Revolves & rotates on axis in 27.3 days – synodic=29.53d
• Always keeping one side facing the Earth
• Resonance due to tidal coupling
Flooding of Basins by Lava
• Lowlands = mare in blue 3.5 billion years old basalt
• Heavily cratered highlands in green 4.5 billion years old
• Farside of Moon has no Maria due to thicker crust
Impact Crater Formation
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Impactor has velocity 10 times rifle bullet
Releases energy 10 times equal mass of dynamite
Impactor vaporized when temperature reaches millions K
Shock wave forms shocked quartz found only in impacts
Rebound can launch rocks without destroying them
Craters Copernicus and Tycho
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Moon is covered by craters of all sizes
Highlands are saturated with craters
Mare/lowlands have fewer craters so are younger
Notice rays, ejecta blankets, secondary craters
Largest Impacts - Mare Orientale
• Mare = sea in Latin are
sites of major impacts
• Note: multiringed basin
• Which flooded with
basalt @ 3.5 billion
years ago = volcanism
Volcanism - Hadley Rille
• 150km long, 1.5km across, 300meters deep
• Formed by flowing lava 3.3 billion years ago
No Atmosphere
to Soften
Shadows
• No Atmosphere => no
erosion by wind water
• Escape velocity too low
• Maximum temperature
of 123C&min of -233C
Only Erosion Is
Slow Surface
Evolution
• Regolith is crushed
rock/dust; covers
surface to depth of a
few meters
• Erosion by
micrometeorites,
solar wind etc.
• Breccias glued with
glass from impacts
Formation of the Moon
• Fission – Protoearth spun so fast that the moon
budded off - but wrong angular momentum
• Coaccretion- formed near Earth from nebula - but
no iron core and no volatiles
• Capture- formed somewhere else- wrong oxygen
isotopes + hard to capture + no iron or volatiles
• Giant Impact- Earth hit by Mars sized asteroid
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Formation of Moon by Giant Impactor
Elapsed time is about a day; moon forms in a year
Earth ends up spinning once in 5 hours, moon in low orbit
Earth was differentiated so moon is made from mantle material
Correct isotope ratio, no iron core, volatiles evaporate
Robin Canup’s simulation
“Eagle Has Landed”
• Apollo 11 lands in Mare Tranquillitatis
• Neil Armstrong and Buzz Aldrin
• 20 July 1969
“One Small Step”
Hammer and Feather
• 6 Moon missions &12 astronauts
• A week to get there
• Apollo 12 and Surveyor 3
Young Drives Moon Rover
Last Man on the Moon?
Giant
Impactor
• Painting by Kaufmann
• Problem of the low density of the Moon
• Solved by Moon being formed from low density
mantle material
• Is it Science? Testable Prediction = Disprovable
Fox TV •
Moon Hoax•
No stars: Not enough exposure
Illuminated astronaut: bright
background
• Parallel shadows: topography
• Flag waving: no atmosphere so
waved longer & liked it wrinkled
Precession of Mercury’s Orbit
• Most of the precession
is due to other planets
• Part is due to General
Relativity
No Atmosphere = No Erosion
But Ice at Mercury’s & Moon’s Poles?
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VLA radar observations see echo from poles which resembles ice
Surface temperature 100K to 700K, but inclination of rotation axes 0º
South Pole of Moon with craters permanently in shadow in white
Hydrogen detected from neutron spectrometer on Lunar Prospector
Lunar Impact