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Chapter 1

A Universe of Life?

Why Study the Universe?

Are we alone? Aliens are everywhere in the movies!

The Day the Earth Stood Still

(1951)

ET: The Extra-Terrestrial

(1982)

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Star Trek (1966-1969)

Alien (1979)

Mars Attacks!(1996)

Common Link?

Common Link?

All are humanoid!

Anthropocentrism

However, extraterrestrial Life may not look like us at all!

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How then will we recognize it?Need to identify the

fundamental characteristics that any kind of Life will

possess

Astrobiology

The study of life in the Universe

Goals of Astrobiology

1. Understanding of the conditions required for life on

Earth

2. The search for life elsewhere in the solar

system

3. The search for life beyond the solar system

Astrobiology is an integrated science

The Role of Astronomy

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Ancient View

The Geocentric Universe

We occupy a special place at the center of the Universe! Modern View

The Earth is just one of 8 planets in our solar system…

Our Sun is just one of roughly a 100 billion stars in our Milky Way Galaxy!

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Our galaxy is just of 100’s of billions of galaxies in our Universe!

How many stars in the Universe?

Try counting every grain of sand on the Earth’s surface!

Lessons from Modern Astronomy

1. The Universe is very large and old

2. The building blocks of life are common

3. The laws of physics are universal

Conclusion?

We are not special!

The universe most likely contains many stars and

planets similar to the earth and Sun

The Role of Planetary Science

Planet Formation

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Extrasolar Planets

Comparative Planetology

Habitable Planets

Those capable of sustaining life

Does not necessarily mean that life is present!

The Role of Biology

The laws of physics and chemistry are the same

everywhere!

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Simple life appeared rapidly but complex life took billions of years to develop on Earth

The most likely type of Extraterrestrial Life!

Searching for life in the Universe

Earth!

Conclusions from studying life on Earth

3 Basic Requirements for Chemically-based Life

1. Atoms to make biological molecules

2. A liquid solvent

3. A source of energy

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3 most likely places to find life in the solar system

Mars

Jupiter’sMoonEuropa

Saturn’s MoonEnceladus

Why?All have or have had liquid water on or beneath their

surfaces!

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Perhaps the most fundamental requirement for Life!

Extrasolar Planets(Exoplanets)

To date 490 planets (Aug 2010) have been detected around other stars!

The Search for Extraterrestrial Intelligence (SETI)