phys 214. planets and life - engineering physicsphys214/lecture1.pdf · 2008-01-25 · phys 214....

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


1. Order

2. Reproduction


4. Energy




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.


1. Order

2. Reproduction


4. Energy




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


1. Order

2. Reproduction


4. Energy




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.


1. Order

2. Reproduction


4. Energy




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)


1. Order

2. Reproduction


4. Energy




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.


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…


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

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

phys 214. planets and life - engineering physicsphys214/lecture1.pdf · 2008-01-25 · phys 214....

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