The document discusses the search for extraterrestrial life, defining it as life not originating from Earth and outlining NASA's goals in this pursuit, such as learning about ourselves and our galaxy. It highlights the criteria for finding Earth-like planets in the habitable 'goldilocks zone' and presents the Fermi paradox, which questions why we have not yet encountered intelligent life despite the universe's age. The ultimate aim is to understand the conditions necessary for life and whether we are alone in the universe.

1. 1
The Search for
The Search for
Extraterrestrial Life
Extraterrestrial Life
What have we been preparing for
in this unit?

2. 2
What is Extraterrestrial Life?
• Life that does not originate from Earth. It is
often also referred to as alien life.

3. 3
What does NASA Hope to Gain
from Searching for Extraterrestrial
Life?
• Learn more about Earth.
• Learn more about Life.
• Gain technology.
• Learn more about ourselves.
• It is inspiring.
• Understand the history of the Earth, the Solar
System and our Galaxy.
• It is cool!

4. 4
What are We Looking For?
• We are looking for extraterrestrial life.
• Evidence of how the solar system was
formed
• Earth-like planets
– Places that support life as we understand it
– We are looking in the Goldilocks zone: a
place that isn’t too far from the sun (cold) but
also not too close (hot) - it’s just right!

5. 5
News!
• Read the article that you have been given.
• Write a short summary of the main points
in your article as well as its relevance to
the search for extraterrestrial life.
• When you are done with the article, wait
quietly for the others to finish.
• When everyone in your group is done,
each person should share their summary
to the group.

6. 6
Where is Everyone?
• The Fermi Paradox basic points are:
– The sun is a young star. There are billions of stars in the galaxy
that are billions of years older.
– Some of these stars likely have Earth-like planets which, if the
Earth is typical, may develop intelligent life.
– Presumably some of these civilizations will develop interstellar
travel, as Earth seems likely to do.
– At any practical pace of interstellar travel, the galaxy can be
completely colonized in just a few tens of millions of years.
• According to this line of thinking, the Earth should have
already been colonized or at least visited. But no
convincing evidence of this exists. Furthermore, no
confirmed signs of intelligence elsewhere have been
spotted, either in our galaxy or the more than 80 billion
other galaxies of the observable universe.

7. 7
What Will We Learn?
• If we understand the needs of life that our
planet currently provides for us, then we
will be able to look for those things in other
planets and possibly find life there. The
hope is that we will find that we are not
alone; we aren’t limited by this planet; and
ultimately we learn more about life.