Download Monday, Oct. 6

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Phys 1810 Lecture 14:
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Total Lunar Eclipse
on Wednesday Oct
8! Mid-eclipse at
5:55 am.
READ BEFORE LECTURE:
– Solar System Chapt 6
– angular momentum (“precisely” box 6-1)
– formation of the moon 8.8
– exoplanets Chapt 15
•
Also can read up on comet structure.
Tour of the Solar System: Mars
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Mars Global Surveyor Mars Orbiter Camera
NASA/JPL/Malin
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Radius ~ ½ of Earth’s; Mass ~ 1/10 of Earth’s.
Water ice crystals over volcanoes
Pole has water ice and CO2 ice.
Red soil due to iron.
Martian Atmosphere.
summary
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• Given the atmospheric pressure can
liquid water currently exist on the
surface of Mars?
Curiosity Rover --- 7 Minutes of Terror
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summary
Curiosity Rover
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• Mount Sharp: How does your mountain
grow?
• A drill hole by Curiosity at mount base
• Will test in its onboard lab for chemistry
• For comparison with different heights on
different Martian features
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Curiosity Rover
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• tilted ancient stream bed?
Curiosity Rover
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• conglomerate rock
• Gravel: size & shape consistent with
transport by H2O
Sedimentary Rock Layers
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• deposited weathered remains of
other rocks
OR
• precipitation from solution
summary
Soil
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• iron-rich clay  red colour
• “blueberries” could form by either
volcanic processes or water related
accretion processes.
Gullies
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• Perhaps permafrost just under the
surface heats up and escapes at
these embankments and forms
gullies.
summary
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• However this is most likely to be a
simple avalanche of debris.
NASA's Mars
Reconnaissance Orbiter
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Gullies caused
by Dry Ice
(frozen CO2)
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Desiccation Patterns
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Earth
When lakes evaporate;
mud dries out.
Mars (in crater)
Permafrost contractions for small
pattern.
Models suggest evaporating lake for
large pattern.
Desiccation Patterns
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•  liquid water between 4.5 and 3.8 billion years ago.
• could occur more recently due to meteorite impact melting
permafrost which fills crater with liquid water under a thick
layer of ice.
• many thousands of years to sublimate a whole lake.
summary
summary
Polar Cap: IR images
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• Polar Ice caps.
• CO2 in the middle panel
• H20 in left panel
Phoenix Landing
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Mars Reconnaissance
Orbiter /NASA
summary
Mars Polar Caps
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Phoenix/NASA
• Subsurface water under ice caps  good
place for microbes (extremophiles) or past
evidence of life.
• Phoenix check conditions.
summary
Perchlorates
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The Phoenix mission to Mars discovered a
chemical that
a)is food for some microbes on Earth.
b) is toxic to some microbes on Earth.
•Toxic for humans
• evidence of carbon
compounds
c) collects water from an atmosphere.
d) is capable of creating on Mars wet
habitats that are about the size of sand
grains.
In past, warm humid
conditions BENEATH
surface suitable.
summary
Mars and cosmic rays
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• Lacking protective magnetosphere.
Tour of the Solar System: Mars
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Mars Express/ESA
• Spectacular images!
• http://www.esa.int/SPECIALS/Mars_Express/ind
ex.html
• http://www.nasa.gov/worldbook/mars_worldbo
ok.html
Citzen Science
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summary
• Check out “Be a Martian” by NASA and
Microsoft.
• Map room  global mosaic of Mars.
• Count craters to help determine ages of
regions.
summary
Astrobiology
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Detecting Our Martian Cousins Some scientists believe that if life exists on Mars,
it could have been delivered there from Earth on interplanetary meteorites. With
funding from NASA’s ASTEP program, a team of researchers is now putting
together an instrument that could test this theory. The Search for Extraterrestrial
Genomes (SETG) project would send an instrument to Mars to search soil or ice
samples for the presence of Earth-like DNA.
• http://astrobiology.nasa.gov/
• Search for water associated with
extrasolar planets.
• Study extremophiles on Earth.
summary
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• Discuss with your neighbours which
aspect of Mars is of most interest to you.
What do you think of colonizing Mars?
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Tour of Solar System Ends
Overview of Solar System
• Relevant to Solar System Formation
Solar System Overview
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• The density in kg/m3
– 1000 for water; if less than this, floats in water.
– 2000-3000 for rocks; 8000 for iron
• Note 2nd last column & density of Earth.
• Ask yourself which planets have densities like rocks/iron? Float on water?
Solar System Overview:
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summary
• For each planet:
– revolve & rotate in the same
direction as other planets?
– primarily composed of rock or of
gas? # Earth Masses, # Earth radii
– small or large? (i.e. closer to Earth
size or Jupiter size?)
– in outer region or inner region of
solar system?
– hot or cold? surface T in Kelvin
– Lots of moons?
– Any other details are welcome 
(eg. Does it have rings? B field?)
Solar System Overview:
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• Terrestrials: Mercury, Venus, Earth,
Mars
• Jovians: Jupiter, Saturn, Uranus,
Neptune
Distances in the Solar System
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Voyager 1 location and
edge of the solar
system?
Extent of Sun’s gravitational
influence.
• Kuiper Belt:
– Debris from solar system formation
– Contains dwarf planets larger than the
dwarf planet Pluto
• Oort Cloud:
– Comets come from these distances
Planetary System Example:
summary
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Dan Foley
• Asteroids 0 – 5.2 AU (i.e. Jupiter’s orbit)
- main Belt between Mars & Jupiter
• Kuiper Belt is thicker than the Asteroid
Belt
• Oort Cloud is spherical
summary
Dwarf Planets:
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Dan Foley
• Ceres in Asteroid Belt
• Kuiper Belt
summary
Solar System Overview: Interplanetary Debris
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Comet Holmes (Pierre Tremblay 2007)
Asteroids visited by spacecraft up to 2008. NASA
Type
Asteroids
Meteroids
Comets
Diameter
> 100m
< 100m
1 – 10 km
Category
rocky
rocky
icy
Comet Ison – approach sun Nov 2013
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• copyright: Damien Peach
summary
Comet Lovejoy: Coma, ion tail, dust tail
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• copyright: Damien Peach
summary
67P/C-G on 26 September
from
a distance of 26.3
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km. Credit:
ESA/Rosetta/NAVCAM
summary
• activity at the neck
• product of ices sublimating &
gases escaping from inside comet,
carrying streams of dust out into
space
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Many scientists define the “edge” of the
solar system as the region where the
gravitational influence of the sun is too
weak to retain comet material in orbit.
What is the extent of the solar system?
a) 5.5 light-hours i.e. the orbit of Pluto
b) 100,000 AU i.e. the outer region of the
Oort Cloud
c) a few 100 AU i.e. the outer region of
the Kuiper Belt
d) 125 AU i.e. the point the Voyager 1
space craft passed Sept 2013
summary
How do we define the edge of the solar system?
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• Interstellar Boundary Explore IBEX.
• Heliosphere – bubble blown by solar
wind has structure
How do we define the edge of the solar system?
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• Interstellar Boundary Explore IBEX.
• The influence of the solar wind ends
beyond the Heliopause- between
120 & 150 AU.
Where is Voyager 1?
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So in the Kuiper
Belt! Not at the edge
of the solar system
defined by the Sun’s
gravitational pull
(outer edge of Oort
cloud).
• 125 AU from Earth, and is expected
to take roughly 300 years to reach
the inner edge of the Oort Cloud and
some 30 000 years to escape it
entirely.
Interstellar Space – can be defined as beyond influence of solar wind
summary
and sun’s magnetic field.
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Solar System Formation
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summary
To understand this we use:
• facts about planets & asteroids,
meteors & comets
• physics e.g.
– properties like temperature
– Newton’s Laws of Motion & gravity
– Angular Momentum
summary
Angular Momentum
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• Angular Momentum == tendency of a body
to keep spinning (rotating) or moving in a
circle (revolving)
(#revolutions/sec)
CONSERVATION OF ANG. MOM.