Astronomy 101
The Solar System
Tuesday, Thursday
2:30-3:45 pm
Hasbrouck 20
Tom Burbine
tomburbine@astro.umass.edu
Course
• Course Website:
– http://blogs.umass.edu/astron101-tburbine/
• Textbook:
– Pathways to Astronomy (2nd Edition) by Stephen Schneider
and Thomas Arny.
• You also will need a calculator.
Office Hours
• Mine
• Tuesday, Thursday - 1:15-2:15pm
• Lederle Graduate Research Tower C 632
• Neil
• Tuesday, Thursday - 11 am-noon
• Lederle Graduate Research Tower B 619-O
Homework
• We will use Spark
• https://spark.oit.umass.edu/webct/logonDisplay.d
owebct
• Homework will be due approximately twice a
week
Astronomy Information
• Astronomy Help Desk
• Mon-Thurs 7-9pm
• Hasbrouck 205
•
The Observatory should be open on clear Thursdays
• Students should check the observatory website at:
http://www.astro.umass.edu/~orchardhill for updated
information
• There's a map to the observatory on the website.
Final
• Monday - 12/14
• 4:00 pm
• Hasbrouck 20
HW #18 and #19
• Due today
Registered Students
100
A or A-
90
B+, B, or B80
C+, C, or C-
Class
Average
70
D+ or D
60
50
F
Without
Dropping
Lowest
Grades
40
30
Median
Grade is
an 81
20
10
0
0
10
20
30
40
50
60
Exam Average
70
80
90
100
Four Science Goals of NASA's
long-term Mars Exploration Program:
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Determine whether Life ever arose on Mars
Characterize the Climate of Mars
Characterize the Geology of Mars
Prepare for Human Exploration
Mars Pathfinder
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Landed July 4, 1997
Weight - 870 kg
Lasted 3 months
Discovery Mission
Objectives of Mars Pathfinder
• Discovery Mission - To prove that the development of
"faster, better and cheaper" spacecraft is possible (with
three years for development and a cost under US $150
million).
• To show that it is possible to send a load of scientific
instruments to another planet with a simple system and at
one fifth the cost of a Viking mission.
• To demonstrate NASA's commitment to low-cost
planetary exploration finishing the mission with a total
expenditure of US$ 280 million, including the launch
vehicle and mission operations.
Sojourner Rover is investigating Yogi the Rock
Spirit and Opportunity
• I used to live in an Orphanage.
It was dark and cold and lonely.
At night, I looked up at the sparkly sky and felt better.
I dreamed I could fly there.
In America, I can make all my dreams come true.....
Thank-you for the "Spirit" and the "Opportunity"
— Sofi Collis, age 9
• Spirit landed in Gusev Crater – appeared basaltic
• Opportunity landed on Meridiani Planum –
appeared to have lots of sedimentary rock
Spirit
Rover tracks
Made by the RAT – Rock Abrasion Tool
Husband Hill
Opportunity
Opportunity Ledge
Rocks seem layered.
Either due to sediments or volcanic ash
Hematite (Fe2O3) formed as deposits in water?
Spirit and Opportunity- now
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Both completed their planned 90-day missions
Both have completed over 2,100 days
Still functioning
Spirit has a broken wheel
Opportunity’s shoulder joint on its robotic arm is
broken
• Spirit is now stuck in soft soil
Taken by Spirit
http://commons.wikimedia.org/wiki/File:PIA05547-Spirit_Rover-Earth_seen_from_Mars.png
Phoenix
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Part of Mars Scout program
First mission run by a university
Landed near Martian North Pole
Dig trenches to search for water
Launched August 4, 2007
Landed May 25, 2008
Mission concluded November 10, 2008
http://en.wikipedia.org/wiki/Image:Phoenix_landing.jpg
http://en.wikipedia.org/wiki/Image:Phoenix_Lander_seen_from_MRO_during_EDL2.jpg
http://en.wikipedia.org/wiki/Image:Patterned_ground_devon_island.jpg
Devon Island
• This polygonal cracking is similar to patterns seen in
permafrost areas
• A likely formation mechanism is that
• ice contracts when the temperature decreases, creating a
polygonal pattern of cracks
• When the temperature rises and the ice expands
back to its former volume, it can’t assume its
former shape
• It then buckle upwards.
http://en.wikipedia.org/wiki/Image:Phoenix_mission_horizon_stitched_high_definition.jpg
http://en.wikipedia.org/wiki/Image:Evaporating_ice_on_Mars_Phoenix_lander_image.jpg
Terrestrial Planets
• Have different surface properties
– Due to size of the planet
– Distance from Sun
– Speed of Planetary Rotation
Meteors
Shaping Planetary Surfaces
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Impact Cratering
Volcanism
Tectonics
Erosion
Cratering
Meteor Crater, Arizona
http://www.solarviews.com/eng/tercrate.htm
Galle Crater, Mars
Mercury
http://geologyindy.byu.edu/eplanet/chapter_5.htm
Callisto (Moon of Jupiter)
http://ase.tufts.edu/cosmos/view_picture.asp?id=726
Earth’s atmosphere
• Small asteroids burn up in the Earth’s atmosphere
before they hit the ground
• Any craters that do form are quickly eroded by
weather generated in the atmosphere
Volcanism
Erosion
• Processes that break down or transport rock
through the action of ice, liquid, or gas
• Movement of glaciers
• Formation of canyons by running water
• Shifting of sand dunes by wind
Energy of Impact (K-T)
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v = 17 km/s
Density = 3,000 kg/m3
Diameter = 2*radius =10 km
Volume = 4/3*π*r3 = 5.23 x 1011 m3
Mass = density*volume
Mass = 1.57 x 1015 kg
Kinetic energy = ½ mv2
Kinetic energy = 2.27 x 1023 Joules
Kinetic Energy = 5.42 x 107 Megatons of TNT
Largest Nuclear Bomb is 100 Megatons of TNT
Result of all this Energy
• Rock melts
• Cools quickly to form glass
Gene Shoemaker
Parts taken from talk
of Bridget Mahoney
Meteor Crater,
Flagstaff, Arizona
• Shoemaker wrote his Ph.D thesis on
Meteor Crater
• Shoemaker did seminal research in the
mechanics of meteorite impacts
Meteor Crater and Shoemaker
• In 1952, Shoemaker hypothesized that
Meteor Crater as well as lunar craters
were created by asteroidal impacts
• USGS sent Shoemaker to the Yucca
flats to investigate small nuclear events
to compare with Meteor Crater,
Shoemaker at Meteor Crater, 1960’s
Coesite
• While doing research in the Yucca flats on
meteorite impact with David Chao, the pair
discovered Coesite
• Coesite (SiO2) is a mineral that is produced
during violent impact
earth.leeds.ac.uk
Chixculub Crater
Taken from presentation by
Amanda Baker
K-T Boundary
• 65 million years ago
• Boundary in the rock
record separating the
Cretaceous and Tertiary
Periods
• Corresponds to one of the
greatest mass extinctions
in history
• Global layer of clay
separating the two periods
• First proposed by Walter
Alvarez
We know it happened but where?
• A Circular geophysical
anomaly, now known to
define the Chicxulub
structure, was originally
identified on the northern
edge of the Yucatan
Peninsula during oil
surveys in the 1950's.
Chixculub
• Translates to “tail of the devil” in Mayan
• The meteorite's estimated size was about 10 km (6 mi) in
diameter, releasing an estimated 4.3×1023 joules of energy
(equivalent to 191,793 gigatons of TNT) on impact.
Chixculub Impact
• http://www.lpl.arizona.ed
u/SIC/impact_cratering/C
hicxulub/Animation.gif
Data
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Seismic, gravity and magnetic
data define a structure ~180
km in diameter.
What happened?
• An asteroid roughly 10 km (6 miles) across hit Earth
about 65 million years ago.
• This impact made a huge explosion and a crater about
180 km (roughly 110 miles) across.
• Debris from the explosion was thrown into the
atmosphere, severely altering the climate, and leading to
the extinction of roughly 60% of species that existed at
that time, including the dinosaurs.
Environmental Damage
• http://www4.tpgi.com.au/users/horsts/climate.htm
• The worst hit organisms were those in the oceans.
• On land, the Dinosauria of course went extinct,
along with the Pterosauria.
• Mammals and most non- dinosaurian reptiles
seemed to be relatively unaffected.
• The terrestrial plants suffered to a large extent,
except for the ferns, which show an apparently
dramatic increase in diversity at the K-T
boundary, a phenomenon known as the fern spike.
• Pterosaurs were flying reptiles
• Dinosaurs lived during the Mesozoic Era, from
late in the Triassic period (about 225 million
years ago) until the end of the Cretaceous (about
65 million years ago).
• Modern birds are considered
to be the direct descendants
of dinosaurs
Tunguska
• Occurred in 1908
• Huge explosion in the atmosphere
• Thought to be asteroid or comet that exploded in
mid-air 6 to 10 kilometers above the Earth's
surface
• Energy of 10 and 15 megatons of TNT
• Equivalent to the most powerful nuclear bomb
detonated in the USA
• There wasn’t a large expedition to the site until
1927
http://en.wikipedia.org/wiki/Image:Tunguska_event_fallen_trees.jpg
http://thunderbolts.info/tpod/2006/image06/060203tunguska2.jpg
•http://geophysics.ou.edu/impacts/tunguska_dc.gif
Evidence for extraterrestrial impact
• No large meteorite fragments were found
• Found were microscopic glass spheres that
contained high proportions of nickel and iridium
Other ideas
• http://en.wikipedia.org/wiki/Tunguska_event
Craters
• Tend to be round unless it is an oblique impact
Tycho crater
on Moon
Diameter 85 km
Depth 4.8 km
http://en.wikipedia.org/wiki/Impact_crater
Moon
Mars
(180 x 65 km).
(380 x 140 km)
http://www.boulder.swri.edu/~bottke/Oblique_craters/oblique.html
Craters
• Complex craters tend to be larger than simple
craters
• Complex Craters
– gravity causes the steep crater walls to collapse, which
makes complex craters very shallow
– Central uplift where the earth rebounds from the
impact
Peak Ring
Central peak Collapses
Complex
(Melosh, 1989)
Different types of craters
• http://www.classzone.com/books/earth_science/te
rc/content/investigations/es2506/es2506page07.cf
m
• Small craters are usually much more common
than larger ones
http://mars.jpl.nasa.gov/gallery/craters/hires/Gusev(plain).jpg
• More craters at smaller sizes - older
Late Heavy Bombardment
• A period of time approximately 3.8 to 4.1 billion
years ago during which a large number of impact
craters are believed to have formed on the Moon
• Determined from the formation ages of impact
melt rocks that were collected
during the Apollo missions.
• Earth must have also been
affected
• (The age dates when the rock
formed.)
Dating through crater counting
(Things to bear in mind)
• Impact rate and size distribution of impacting
bodies
• Temporal and spatial variations in impactor
population
• Temporal variation in the target
• Crater degradation
• Secondary impacts
• Need for measured surface ages to calibrate
counting
Calibration
• Moon – we have samples from specific places
• Other planets – no samples
http://www.psi.edu/projects/mgs/chron04c.html
• Cratering rate will be different on Mars compared
to the Moon
– Mars has larger mass so larger flux (gravitational
focusing)
– Mars closer to asteroid belt (more possible impactors)
Any Questions?