Transcript Strigiphilus garylarsoni

Life on
Earth
What We Learn From Other
Planetary Systems
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Protoplanetary Disks
Accretion of Planets
Expulsion and Migration of Planets
About 1000 extrasolar planets known
Our Solar System may be unusual?
Protoplanetary Disks in Orion
The Galactic Habitable Zone?
• Center: Too Violent, Stars too massive and
short-lived
• Fringes: Not enough material to make suitable
planets
• Middle: Stable but frequent star formation,
expulsion of new material
Do We Need Jupiter for Life?
• Close-in Jupiter: other planets not possible
• Jupiter in eccentric orbit: other planets won’t
have stable orbits
• Distant Jupiter in circular orbit is a stabilizing
influence
• Jupiter sweeps up a lot of potential impactors
Do We Need the Moon for Life?
• Moon’s gravity causes the earth’s axis to
precess
• Mars’ axis tilt can be up to 60 degrees
• Moon totally dominates effects of Sun and
other planets, keeps earth’s axis tilt within
reasonable limits
“Of course, long before you mature,
most of you will be eaten.”
“The picture’s
pretty bleak,
gentlemen. The
earth’s climate is
changing, the
mammals are
taking over, and we
all have brains the
size of a walnut.”
“Now this
end is called
the
thagomizer,
after the late
Thag
Simmons.”
“Evolution’s been good to you, Sid.”
Prebiotic Evolution
• The basic molecules of organic chemistry are
easily made
• The first self-replicating molecule was almost
certainly not DNA
• DNA assembles from simpler materials all the
time
Plants and Animals
• CO2 + H2O + Energy = Sugars, Starches, etc. +
O2 (toxic waste)
• O2 is actually toxic (even to us!)
• Idea: Take the sugars and starches (from
somebody else) combine it with the waste
O2, and get energy
Amazing Events in Life History
• Sex - Who Needs It?
• We are a team - Mitochondria
• The Great Freeze 900-600 m.y. ago
– What survived and how?
• Mass Extinctions
– Dinosaurs = 4th worst
– Permian extinction (220 m.y. ago) took out 90%
of all species
Classification of Dogs and Humans
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Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order Carnivora (Dogs) Primates (Humans)
Family Canidae
Hominidae
Genus Canis
Homo
Species familiaris
sapiens
“Actually, I considered
this an extreme honor.
Besides, I knew no one
was going to write and
ask to name a new
species of swan after
me. You have to grab
these opportunities
when they come along.”
Strigiphilus
garylarsoni
The Five Kingdom System
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Animals
Plants
Protista (one-celled organisms)
Fungi
Bacteria*
Ediacaran Fossils? (ca. 700 m.y. ago)
What’s Bigger Than a Kingdom?
• Bacteria differ from all other kingdoms in
lacking a cell nucleus
• We need a bigger box
• Superkingdoms or Domains
– Monera (Bacteria)
– Archaea
– Eukarya (have cell nucleus)
• Need electron microscopes and molecular
biology to see differences
Mass Extinctions
Impacts on Earth
Recent Impact – Meteor Crater
Manicouagan, Quebec
Sudbury, An Ancient Impact Site
A Shatter Cone
Fallback Breccia
Bessel: A Simple Crater
Ejecta
around
Timocharis
Tycho: A
Central-Peak
Crater
How Central Peaks Form
Upheaval Dome, Utah
Schrodinger: A Peak-Ring Crater
Mare Orientale
A Multiple-Ring
Impact Basin
Impacts and Extinctions
• The problem isn’t killing things, it’s that
anything survives.
• Immediate: Fireball, Blast, Ejecta
• Hours: Tsunamis, Incoming ejecta
• Days: Wildfires, Dust Cloud, Sulfur Aerosols
• Months: Darkness, Death of plants and
animals, acid rain
• Years: CO2 or Methane pulse?
Were The Dinosaurs Failures?
Dinosaurs: 150,000,000 years
Recorded History: 5000 years
• For every year of recorded history, the
dinosaurs had 30,000 years
• For every day of recorded history, the
dinosaurs had 82 years
• For every minute of recorded history, the
dinosaurs had three weeks