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HNRT 228 Astrobiologyw/ Dr. H. Geller

Physical Origins

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The Phase Diagram

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iClicker Question

• What is the name of the phase change from liquid to gas?– A Vaporization– B Condensation– C Deposition– D Sublimation– E None of the above

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iClicker Question

• What is the name of the phase change from solid to gas?– A Vaporization– B Condensation– C Deposition– D Sublimation– E None of the above

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iClicker Question

• What is the name of the phase change from gas to liquid?– A Vaporization– B Condensation– C Deposition– D Sublimation– E None of the above

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iClicker Question

• What is the name of the phase change from gas to solid?– A Vaporization– B Condensation– C Deposition– D Sublimation– E None of the above

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iClicker Question

• What is the name of the phase change from liquid to solid?– A Vaporization– B Condensation– C Deposition– D Sublimation– E None of the above

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Recall Unique Properties of Water

Density vs. Temperature

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iClicker Question

• The density of liquid water is greater than the density of solid water (ice).– A True– B False

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iClicker Question

• There is always more to an iceberg beneath the water’s surface than above the water’s surface– A because liquid water is less dense than ice– B because liquid water is more dense than ice– C because ice is more dense than liquid water– D because water and ice are two different

molecules– E This is a false statement because there’s

always more of an iceberg above the surface than beneath the surface

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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

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iClicker Question

• An extrasolar planet (aka exoplanet) is– A a planet that is larger than our Sun– B a planet that orbits a star other than

our Sun– C a planet located in another galaxy

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iClicker Question

• A habitable planet is– A a planet that has oceans like the

Earth– B a planet that has life of some kind– C a planet that may or may not

have life, but that has environmental conditions under which it seems that life could arise or survive

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iClicker Question

• By a geocentric view of the universe, we mean– A the idea that Earth resides at the

center of the universe– B the idea that Earth is the only

planet with life in the universe– C a view of the universe shaped by

current understanding of geological science

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iClicker Question

• According to current scientific understanding, life on Earth– A was exceedingly improbable– B arose quite soon after conditions

allowed it– C may have been inevitable, but

took billions of years to arrive

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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 scanning the skies for signals

from alien civilizations– B sending spacecraft to the

planets– C 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 10 years– B 100 years– C 1000 years– D 10,000 years– D 100,000 years

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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.

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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 Mars– B Titan– C Venus– D Europa– E Io

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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

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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

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Some Words onIn-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

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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.

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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.

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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.

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For Next Meeting

• Read Chapter 2 in textbook– In general you should be reading

ahead for the upcoming classes