Transcript Lecture 2 notes - Department of Physics and Astronomy

HNRT 228 Astrobiology
w/ Dr. H. Geller
Spring 2016
Physical Origins
1
The Phase Diagram
2
iClicker Question
• What is the name of the phase
change from liquid to gas?
–
–
–
–
–
A
B
C
D
E
Vaporization
Condensation
Deposition
Sublimation
None of the above
3
iClicker Question
• What is the name of the phase
change from solid to gas?
–
–
–
–
–
A
B
C
D
E
Vaporization
Condensation
Deposition
Sublimation
None of the above
4
iClicker Question
• What is the name of the phase
change from gas to liquid?
–
–
–
–
–
A
B
C
D
E
Vaporization
Condensation
Deposition
Sublimation
None of the above
5
iClicker Question
• What is the name of the phase
change from gas to solid?
–
–
–
–
–
A
B
C
D
E
Vaporization
Condensation
Deposition
Sublimation
None of the above
6
iClicker Question
• What is the name of the phase
change from liquid to solid?
–
–
–
–
–
A
B
C
D
E
Vaporization
Condensation
Deposition
Sublimation
None of the above
7
Recall Unique Properties of Water
Density vs. Temperature
8
iClicker Question
• The density of liquid water is greater
than the density of solid water (ice).
–A
–B
True
False
9
iClicker Question
• There is always more to an iceberg beneath the
water’s surface than above the water’s surface
–
–
–
–
A
B
C
D
– E
because liquid water is less dense than ice
because liquid water is more dense than ice
because ice is more dense than liquid water
because water and ice are two different
molecules
This is a false statement because there’s
always more of an iceberg above the surface
than beneath the surface
10
Overview of Chapter 1
• 1.1 The Possibility of Life Beyond Earth
– Some discussion in 1st meeting
• What life are scientists searching for?
• Is it reasonable to expect life elsewhere in the universe?
• 1.2 The Scientific Context of the Search
– Usefulness of astronomy in search for life
– Utility of planetary science in search for life
– Earth’s biology and its usefulness for search for life
• 1.3 Places to Search
– Where should we search?
• In our solar system
• In our galaxy
11
iClicker Question
• An extrasolar planet (aka exoplanet) is
–A
–B
–C
a planet that is larger than our Sun
a planet that orbits a star other than
our Sun
a planet located in another galaxy
12
iClicker Question
• A habitable planet is
–A
–B
–C
a planet that has oceans like the
Earth
a planet that has life of some kind
a planet that may or may not have
life, but that has environmental
conditions under which it seems
that life could arise or survive
13
iClicker Question
• By a geocentric view of the universe,
we mean
–A
–B
–C
the idea that Earth resides at the
center of the universe
the idea that Earth is the only
planet with life in the universe
a view of the universe shaped by
current understanding of
geological science
14
iClicker Question
• According to current scientific
understanding, life on Earth
–A
–B
–C
was exceedingly improbable
arose quite soon after conditions
allowed it
may have been inevitable, but took
billions of years to arrive
15
iClicker Question
• The correct order of the eight official
planets in our Solar System, from closest
to farthest from the Sun is
– A
Mercury, Venus, Earth, Mars, Saturn,
Jupiter, Uranus, Neptune, Uranus
– B
Mercury, Venus, Earth, Mars, Jupiter,
Uranus, Saturn, Neptune
– C
Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, Neptune
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iClicker Question
• Today, the research known as SETI is
conducted primarily by
–A
–B
–C
scanning the skies for signals
from alien civilizations
sending spacecraft to the planets
using telescope to observe
extrasolar planets
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iClicker Question
• If we sent one of our current
spacecraft to a nearby star (besides
the Sun), the trip would take about
–
–
–
–
–
A
B
C
D
D
10 years
100 years
1000 years
10,000 years
100,000 years
18
iClicker Question
• Scientists today are interested in
searching for life on Mars because
–A
we see clear evidence of a past
civilization on Mars.
–B
Mars contains frozen water ice at
its polar caps.
–C
evidence suggests that Mars had
liquid water on its surface in the distant
past.
19
iClicker Question
• Based on current evidence, the object
in our Solar System most likely to
have a deep, subsurface ocean of
liquid water is
–
–
–
–
–
A
B
C
D
E
Mars
Titan
Venus
Europa
Io
20
iClicker Question
• Based on the way scientists view the study of
astrobiology, failure to find life on any other
world would mean
– A
the whole subject has been a waste of time.
– B
we must have done something wrong, since life
has to exist beyond Earth
– C
we have learned important lessons about the
conditions that made life on Earth possible
21
Overview of Chapter 1
• 1.4 The New Science of Astrobiology
– New, are you kidding?
• Bio-astronomy, exobiology
• Even Galileo and Kepler considered where else in our
solar system we might find life
• IAU conference on bioastronomy in 1959!
– Astrobiology according to Geller
• ODDS
–
–
–
–
origins
development
distribution
search
22
Some Words on
In-Class Discussion Groups
• Three to four persons in a group
• To start
– Determine leader and recorder (writer)
• This will alternate each meeting
• Write the answer to discussion questions
so that I can be sure you are addressing
the question correctly
• Use complete sentences
• Answer in terms that address scientific
issues of questions
23
Discussion Questions
• Question #1:
– A) Can life exist in places that never
receive sunlight?
• If Yes » What types of life forms could
exist?
• If No » Cite the physical reasons why life
cannot exist without sunlight.
– B) What elements are the most important
for the existence of life? Explain your
reasoning.
24
Discussion Questions
• Question #2:
– A) Consider the following statement:
• "For a life form to exist, liquid water must be present in the
local environment in at least small amounts or for short time
periods."
• Do you agree or disagree with this statement.
• If You Agree » Explain why liquid water is necessary.
• If You Disagree » What type of life could exist and what
would the environment be like?
– B) We know that there are 8 major planets orbiting
the Sun in our solar system. Would you expect there
to be other planets orbiting other stars outside our
solar system? Explain why or why not.
25
Discussion Questions
• Question #3:
– A) Can any forms of life exist in environments with
temperatures much greater than 100°C (the boiling point of
water) or much less than 0°C (the freezing point of water)?
• If Yes » What types of life forms could exist at either of these
temperatures? State the form of life and the corresponding
temperature.
• If No » Cite the physical reasons why life cannot exist at either
of these temperatures.
– B) Which of the following elements must be present for life to
exist. Explain your reasoning for each choice. (consider
hydrogen, potassium, zinc, oxygen, calcium, uranium,
magnesium, sulfur, carbon, nitrogen, iron, and sodium)
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Discussion Questions
• Question #4:
– A) Describe an environment on Earth
that would not allow any form of life to
exist. Cite specific examples and explain
why these environments cannot support
life.
– B) Do scientists have evidence that
indicates whether life exists anywhere
other than Earth? Explain your
reasoning.
27
For Next Meeting
• Read Chapter 2 in textbook
– In general you should be reading ahead
for the upcoming classes
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