Phys 214. Planets and Life
Dr. Cristina Buzea
Department of Physics
Room 259
E-mail: [email protected]
(Please use PHYS214 in e-mail subject)
Lecture 1. Course overview
January 7th
Phys 214. Planets and life
Textbook required
“Life in the Universe” Second Edition 2007
By Jeffrey Bennett & Seth Shostak
Other reading resources:
1. Astrobiology: A Multi-Disciplinary Approach(2004) by Jonathan Lunine
2. An Introduction to Astrobiology (2004)
by Iain Gilmour, Mark A. Sephton
3. Planets and Life: The Emerging Science ofAstrobiology (2007)
by Woodruff T. Sullivan & John Baross
Other information on the website:http://www.physics.queensu.ca/~phys214/
Planets and Life - OverviewPlanets and Life - Overview
• What is life?
• Common ancestor of life on Earth
• The elements of life and where were they made
• The Cosmic calendar
• How big is the Universe
• Solar system, planets, moons, small bodies
• How did the solar system formed
• Planetary nebulae
• Extrasolar planets
• Habitability
• Overview of possible places for life in the Solar system
What is life?What is life?
1. Order
2. Reproduction
3. Grows and develops
4. Energy
5. Responds to the environment
6. Evolutionary adaptation
Copyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Molecules in living organisms exhibit order.
They are arranged in patterns that make cell
structures.
Exception: crystals.
Spiral patterns in two single celled organism
What is life?What is life?
1. Order
2. Reproduction
3. Grows and develops
4. Energy
5. Responds to the environment
6. Evolutionary adaptation
Copyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Living organisms reproduce or are products
of reproduction.
A single-celled organism (amoeba) dividing into two cells.
Exceptions:
Viruses - incapable or reproducing on
their own, need a living organism.
Prions - infectious proteins, agents of
mad cow disease.
What is life?What is life?
1. Order
2. Reproduction
3. Grows and develops
4. Energy
5. Responds to the environment
6. Evolutionary adaptation
Copyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Living organisms grow and develop in
patterns in part by heredity, traits passed to an
organism from its parents.
Nile crocodile emerging from its shell.
Exception:
fire
What is life?What is life?
1. Order
2. Reproduction
3. Grows and develops
4. Energy
5. Responds to the environment
6. Evolutionary adaptation
Copyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Life uses energy from the environment to
create and maintain patterns of order within
their cells, to reproduce and grow.
Tube worms living near deep-sea vents obtain energy from
chemical reactions made possible in part by heat released
from the volcanic vent.
Exceptions: Some organisms can survive for
very long period of times in dormant state.
What is life?What is life?
1. Order
2. Reproduction
3. Grows and develops
4. Energy
5. Responds to the environment
6. Evolutionary adaptation
Copyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Life interacts with the surroundings and
responds to environmental changes.
A jackrabbit’s ears flush with blood, the blood flow adjusts
automatically to help the animal maintain a constant
temperature by adjusting the heat loss from the ears.
Exceptions: human-made devices
(thermostat)
What is life?What is life?
1. Order
2. Reproduction
3. Grows and develops
4. Energy
5. Responds to the environment
6. Evolutionary adaptation
Copyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Life evolves as a result of the interactions
between organisms and the environment,
leading over time to evolutionary
adaptations that make species better suited
for the environment.
A pygmy seahorse is camouflaged in its coral surroundings.
Cells: the basic units of lifeCells: the basic units of life
Bacteria Amoebas Plant cells Animal cellsCopyright 2007 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Some organisms consist of single cells, others are complex structures with trillions
of cells working cooperatively, having specialized tasks.
Life on Earth- a common ancestorLife on Earth- a common ancestor
All Earth life uses only left-handedAll Earth life uses only left-handed
amino acids.amino acids.
Every living cell on Earth uses theEvery living cell on Earth uses the
same molecule - ATP - to storesame molecule - ATP - to store
and release energy!and release energy!
All life on Earth passes hereditaryAll life on Earth passes hereditary
information in the same wayinformation in the same way
with DNAwith DNA
Life on Earth- a common ancestorLife on Earth- a common ancestor
Based on biochemical and genetic relationships, life is classified into 3 domains.
Mutations Mutations –– the molecular basis for evolution. the molecular basis for evolution.
Life on EarthLife on Earth
•• Just 4 elements - O, C, H, N - make up about 96% of the mass of typical livingJust 4 elements - O, C, H, N - make up about 96% of the mass of typical livingcells.cells.
•• Most of oxygen is part of WATER molecules.Most of oxygen is part of WATER molecules.
The elements of life were made in stars!The elements of life were made in stars!
Older stars are mostly made up of HOlder stars are mostly made up of H
and He.and He.
The elements of life The elements of life –– C, O, N, and C, O, N, and
heavier elements were formed byheavier elements were formed by
nuclear fusion in stars.nuclear fusion in stars.
Younger stars, like our Sun, containYounger stars, like our Sun, contain
higher proportions (up to 2%) ofhigher proportions (up to 2%) of
their mass in the form of heaviertheir mass in the form of heavier
elements.elements.
Galaxies are recycling plants, reusingGalaxies are recycling plants, reusing
material expelled from dyingmaterial expelled from dying
stars to make new generations ofstars to make new generations of
stars and planetsstars and planets
We are star stuff !We are star stuff !
The process of stellar and galactic recycling operate throughout the Milky
Way, as well as every similar galaxy in the Universe.
•• Perhaps most other star systems have the necessary raw ingredients toPerhaps most other star systems have the necessary raw ingredients to
build Earth-like planets & LIFE.build Earth-like planets & LIFE.
The Big BangThe Big Bang
According to current astronomical data, the Universe is approximatelyAccording to current astronomical data, the Universe is approximately14 billion years old 14,000,000,000.14 billion years old 14,000,000,000.
The Cosmic CalendarThe Cosmic Calendar
Jan 1 Jan 1 –– The Big Bang The Big Bang
Feb Feb –– The Milky Way The Milky Way
Many generations of stars lived and
died in the subsequent months,
enriching the galaxy with heavier
elements.
Sept Sept –– Solar System & Earth Solar System & Earth
(about 4.5 billion years ago)
Sept 22 Sept 22 –– early life on Earth early life on Earth
(more than 3.5 billion years ago) living
organisms remained microscopic in
size until Dec 17
The Big Bang is on Jan 1st, and the present is
the stroke of midnight on Dec 31. Each month
is a little more than one billion years, each
day ~ 40 million years, each second more
than 400 years.
The Cosmic CalendarThe Cosmic Calendar
Dec 17 Dec 17 –– Cambrian explosion Cambrian explosion
(545 million years ago)Incredible animal diversity
Dec 26 Dec 26 –– Rise of dinosaurs Rise of dinosaursDec 30 Dec 30 –– Dinosaurs extinction Dinosaurs extinction
(65 million years ago)The death of dinosaurs allowed other
species to evolve.
Dec 31, 9 pm Dec 31, 9 pm –– early hominids early hominids
(human ancestors)60 million years later after dinosaurs
extinction…
The Cosmic CalendarThe Cosmic Calendar
Dec 31, 11:58 pm Dec 31, 11:58 pm –– Modern humans evolve Modern humans evolve
The entire history of human civilization fits into just the last half-minute!
The fact that the Universe is so much older than Earth means that could
be many worlds that had plenty of time for life to arise and evolve.
How big is the Universe?How big is the Universe?
The age of the universe poses some limitations on the portion of the universe thatThe age of the universe poses some limitations on the portion of the universe that
we can observe with telescopes, due to the limited value of the speed of light.we can observe with telescopes, due to the limited value of the speed of light.
When we look to great distances, we are also looking far back into the past.
By counting the galaxies in the photo, the observable universe has an estimate ofBy counting the galaxies in the photo, the observable universe has an estimate of
about 100 billion galaxies.about 100 billion galaxies.
Number of stars in the observable universe
The Universe has an estimate of 100 billion galaxies.
Milky Way has an estimate of 100 billion stars.
100 billion x 100 billion =
10,000,000,000,000,000,000,000=
1022 stars
Due to the incredible size of the universe, our search for extraterrestrial life will
probably be limited to within our Milky Way.
The Solar SystemThe Solar System
Two major types of planetsTwo major types of planets
Terrestrial & Jovian.
Terrestrial planets - small, made mostly of rock & metals with highTerrestrial planets - small, made mostly of rock & metals with high
densities, near the Sundensities, near the Sun
Jovian planets -large, made mostly of gases and liquids with lowJovian planets -large, made mostly of gases and liquids with low
densities, far from the Sundensities, far from the Sun
Small bodies and dwarf planets orbiting the SunSmall bodies and dwarf planets orbiting the Sun
Small bodies orbiting the SunSmall bodies orbiting the Sun
MoonsMoons
Terrestrial planets have few moons.
Mercury and Venus have no moons.
Mars has two very small moons, probably captured asteroids.
Moons are common for Jovian planets,totalling at least 150 moons together.
Nebular theoryNebular theory
The formation of the solarThe formation of the solar
system according tosystem according to
the nebular theory hasthe nebular theory has
four steps:four steps:
1. Contraction into a1. Contraction into a
planetary nebulaplanetary nebula
2. Condensation2. Condensation
3. Accretion3. Accretion
4. Clearing4. Clearing
Planetary NebulaePlanetary Nebulae
Extrasolar planets
HabitabilityHabitability
Requirement for liquid waterThe habitable zone becomes increasingly smaller and closer-in for stars of lower
luminosity.
Galactic constraints
Earth Habitability Earth Habitability –– climate stability climate stability
1. Moon: stability of Earth tilt1. Moon: stability of Earth tilt
Earth Habitability Earth Habitability –– climate stability climate stability
3. Global magnetic field3. Global magnetic field
- protects Earth from the energetic- protects Earth from the energetic
particles of the solar windparticles of the solar wind
- impairs solar wind stripping of Earth- impairs solar wind stripping of Earth
atmosphereatmosphere
Environmental requirements for habitabilityEnvironmental requirements for habitability
Potential liquids for life
Life needs:Life needs:1) Source of molecules from which to build living cells1) Source of molecules from which to build living cells2) Source of energy to fuel metabolism2) Source of energy to fuel metabolism3) Liquid medium 3) Liquid medium –– most likely water most likely water
Moon and MercuryMoon and Mercury
The less likely habitable places inThe less likely habitable places in
the Solar Systemthe Solar System
-- much smaller than Earth much smaller than Earth
(gases escaped into space)(gases escaped into space)
-- lost their internal heat (no lost their internal heat (no
plate tectonics and volcanismplate tectonics and volcanism
Mercury
The closest planet to the Sun
Dayside temperature 425deg C
Night temperature -175 deg C
Moon Mercury
Venus
Strong greenhouse effects
CO2 more than 96% of Venus
atmosphere
(1% CO2 for Earth atmosphere)
- Surface temperature 470o C
- Pressure 90 times higher than
at Earth surface
- sulfuric acid clouds
Mars
• Polar temperatures at the winter pole
–130oC (CO2 condenses into dry ice)
•At the summer pole CO2 sublimates
into gas
•The difference in the atmospheric
pressure induces pole-pole strong
winds and global dust storms
The moons of Mars
Mars
Water on Mars
• Mars had once flowing water!
• Now the surface pressure is too
low for liquid water.
• Mars retains enough internal heat
for underground liquid water.
Water on Mars
Life on Mars?
Martian meteorite
contains microscopic
structures interpreted
as fossils of ancient
life.
Coincidental patterns: The face on Mars The Happy face on Mars!
Jovian planets (gas giants)Jovian planets (gas giants)
Moons of Jovian planetsMoons of Jovian planets
Jupiter moon GanymedeJupiter moon Ganymede
and Saturn moon Titanand Saturn moon Titan
are larger than planetare larger than planet
MercuryMercury
Saturn’s moon Titan (2,575 km) Mercury (2,440 km radius)
Ganymede (2,634 km), Callisto (2,403 km), Io (1,821 km), Europa (1,565 km)
Moons of Jovian planetsMoons of Jovian planets
Io (1,821 km), Europa (1,565 km), Titan (2,575 km)
Many moons are planetlike in almost every way except their orbits.Some moons are geologically active, others have water, other atmosphere.
Io is the most volcanically active world in the Solar System.Europa has occasionally water or ice floating on its surface.Titan has an atmosphere thicker than the Earth.
Large moons around jovian planets offer a second category (after terrestrialLarge moons around jovian planets offer a second category (after terrestrialplanets) of potentially habitable worlds.planets) of potentially habitable worlds.
JupiterJupiter’’s moon Ios moon Io
Strong tidal stresses and
heating make Io the most
active body of the Solar
system.
JupiterJupiter’’s moon Europas moon Europa
Europa is covered with an ice shell.
Gravitational measurements and surface
feature suggest a liquid water ocean under
the outer layer of ice
SaturnSaturn’’s Moon Titans Moon Titan
Pressure 1.5 time the one of Earth
Surface temperature –180oC.
Atmosphere 90% nitrogen, but almost no
oxygen.
Rivers and lakes of liquid methane.
SaturnSaturn’’s Moon Enceladuss Moon Enceladus
Has liquid water below the surface exhibiting cryovolcanism.
Geysers erupt from its surface due to pockets of liquid water at temperatures of
0oC, despite a surface temperature of -200oC.
What conditions can life survive?What conditions can life survive?
ExtremophileExtremophile organisms - that live and some can organisms - that live and some cansurvive only in the extreme conditions.survive only in the extreme conditions.
Thermophiles - deep-sea hydrothermal vents (121oC)Endolithic Bacteria - living in rocksXerophile - dry conditionsRadioresistant - withstand massive doses of radiationEndospores - special cells allowing to become dormantVacuum, heat, pressure, radiation, long preservation(bacteria revived and cultured after some 25 million years ofencapsulation in the guts of a resin-trapped bee.)
Bacteria survives trip to the MoonBacteria survives trip to the Moon
Interior view of Surveyor
3 TV camera; surviving
microorganisms cultured
from the polyurethane
foam insulation. Surveyor
3 landed on the moon on
April 20, 1967.
Culture plate from 3 camera foam sample showing
Streptococcus mitis. a common harmless bacteria from
the nose, mouth& throat in humans.
Streptococcus mitis survived:
launch
• space vacuum
• 3 years of radiation exposure
• deep-freeze at an average temperature of only 20 K
• no nutrient, water or energy source
Impacts and extinctionsImpacts and extinctions
At least 5 major mass extinctions, including the K-TAt least 5 major mass extinctions, including the K-T
(cretaceous-Tertiary boundary) occurred on Earth.(cretaceous-Tertiary boundary) occurred on Earth.
The rate of extinction for plants and animals over the past
500 millions years.
Impacts
• 25 million particles each day
• Add a total of 20,000-40,000
tons per year
• Many asteroids crosses the
Earth’s orbit.
The question is not whether but
WHEN a future impact occur.
50 m meteor?
Impacts and extinctionsImpacts and extinctions
Phys 214. Planets and LifePhys 214. Planets and Life
Dr. Cristina Buzea
Department of Physics
Room 259
E-mail: [email protected]
(Please use PHYS214 in e-mail subject)
Wednesday - Questionnaire