is there anyone else out there? the drake equation number of stars # stars with planet # planets...

Is there anyone else out there?Is there anyone else out there?

The Drake EquationThe Drake Equation

Number of stars# stars with planet# planets that could support life# number that evolve life# fraction of life that becomes smart# fraction that can/want to communicate # how long they last before blowing up

Number of stars# stars with planet# planets that could support life# number that evolve life# fraction of life that becomes smart# fraction that can/want to communicate # how long they last before blowing up

What is geophysics?What is geophysics?

The use of physics to study the Earth and planetsThe use of physics to study the Earth and planets

Geodynamic simulationsGeodynamic simulationsSolving the whole world: mantle convectionSolving the whole world: mantle convection

Geodynamic simulationsGeodynamic simulationsmantle convection: hot air rises?

So does hot mantle.And when it does, it does

this:

mantle convection: hot air rises?So does hot mantle.And when it does, it does

this:

The continents drift!This is called plate tectonics.

The continents drift!This is called plate tectonics.

Why is the mantle important for Earth?Why is the mantle important for Earth?

•Water & CO2 both come out of volcanoes into the atmosphere.•Both are recycled back into the mantle by plate tectonics (oceans recycled through the mantle over 10 times through Earth’s history!)

On Earth, plate tectonics controls the atmosphere and oceans (and so it also affects life…).-> The plate tectonic cycle helps control global warming

•Water & CO2 both come out of volcanoes into the atmosphere.•Both are recycled back into the mantle by plate tectonics (oceans recycled through the mantle over 10 times through Earth’s history!)

On Earth, plate tectonics controls the atmosphere and oceans (and so it also affects life…).-> The plate tectonic cycle helps control global warming

Spot the differenceSpot the difference

Venus

ca. 1930

Venus ca. 1930

Magellan mission in early 90’s:

1. No plate tectonics2. No continents

3. The surface of Venus is all about the same age

Magellan mission in early 90’s:

1. No plate tectonics2. No continents

3. The surface of Venus is all about the same age

Why wouldn’t Venus have plate tectonics like

Earth?

Why wouldn’t Venus have plate tectonics like

Earth?

SunSun

Theory: No water, no plate tectonicsTheory: No water, no plate tectonics

EarthEarth

VenusVenus

MarsMars

WaterWater

So Earth is lucky cause its got little CO2.

But where did all the CO2 go???

So Earth is lucky cause its got little CO2.

But where did all the CO2 go???

So life protects the Earth from runaway

greenhouse and boiling oceans…

But water and oceans are needed for life…?




Earth is 4.5 billion years oldWe see life back to nearly 4

billion years, it could be older













Ancient zircon grains: earliest life on EarthAncient zircon grains: earliest life on Earth

Tough zircon grains in younger rocksZircon dates are >4.0Ga, even as old as

4.4Ga. This is just after the world formed.

Oldest exposed rocks (Canada) are ~4.0Ga.

These zircons are from worlds oldest continents.

Their chemistry indicates liquid water too.

They have diamonds in them...and the diamond chemistry indicates the presence of life! (Maybe)

The big flukeThe big fluke

•Made the moon•Evaporated Earth’s atmosphere•Later atmosphere from volcanoes was thin and cool so oceans could form, and life could evolve•Venus never lost its big blanket so it was always to hot for oceans•It even has a “fossil atmosphere” (the fossil is Argon. Earth’s got blasted into space).

So no life on Venus? Ever?

So no life on Venus? Ever?

Well, not so quick….Well, not so quick….

•2002: El Paso, Texas -> detected strange chemicals in the clouds•H2S & SO2 together, carbonyl sulphide, and no CO•So what? These are not naturally found together, only when life-forms are producing them.

•2002: El Paso, Texas -> detected strange chemicals in the clouds•H2S & SO2 together, carbonyl sulphide, and no CO•So what? These are not naturally found together, only when life-forms are producing them.

Bacteria in clouds?Why not, they live there on Earth.

Bacteria in clouds?Why not, they live there on Earth.

Life can turn up in the strangest places.

Life can turn up in the strangest places.

Earth might be rare, but maybe that doesn’t

matter.

Earth might be rare, but maybe that doesn’t

matter.

Also check out:http://www.cosmosmagazine.com/node/1658

Also check out:http://www.cosmosmagazine.com/node/1658

is there anyone else out there? the drake equation number of stars # stars with planet # planets...

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