1 HNRT 228 Astrobiology w/ Dr. H. Geller Physical Origins

2 The Phase Diagram

3 iClicker Question What is the name of the phase change from liquid to gas? –AVaporization –BCondensation –CDeposition –DSublimation –ENone of the above

4 iClicker Question What is the name of the phase change from solid to gas? –AVaporization –BCondensation –CDeposition –DSublimation –ENone of the above

5 iClicker Question What is the name of the phase change from gas to liquid? –AVaporization –BCondensation –CDeposition –DSublimation –ENone of the above

6 iClicker Question What is the name of the phase change from gas to solid? –AVaporization –BCondensation –CDeposition –DSublimation –ENone of the above

7 iClicker Question What is the name of the phase change from liquid to solid? –AVaporization –BCondensation –CDeposition –DSublimation –ENone of the above

8 Recall Unique Properties of Water Density vs. Temperature

9 iClicker Question The density of liquid water is greater than the density of solid water (ice). –ATrue –BFalse

10 iClicker Question There is always more to an iceberg beneath the water’s surface than above the water’s surface –Abecause liquid water is less dense than ice –Bbecause liquid water is more dense than ice –Cbecause ice is more dense than liquid water –Dbecause water and ice are two different molecules –EThis is a false statement because there’s always more of an iceberg above the surface than beneath the surface

11 Overview of Chapter 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

12 iClicker Question An extrasolar planet (aka exoplanet) is –Aa planet that is larger than our Sun –Ba planet that orbits a star other than our Sun –Ca planet located in another galaxy

13 iClicker Question A habitable planet is –Aa planet that has oceans like the Earth –Ba planet that has life of some kind –Ca planet that may or may not have life, but that has environmental conditions under which it seems that life could arise or survive

14 iClicker Question By a geocentric view of the universe, we mean –Athe idea that Earth resides at the center of the universe –Bthe idea that Earth is the only planet with life in the universe –Ca view of the universe shaped by current understanding of geological science

15 iClicker Question According to current scientific understanding, life on Earth –Awas exceedingly improbable –Barose quite soon after conditions allowed it –Cmay have been inevitable, but took billions of years to arrive

16 iClicker Question The correct order of the eight official planets in our Solar System, from closest to farthest from the Sun is –AMercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, Neptune, Uranus –BMercury, Venus, Earth, Mars, Jupiter, Uranus, Saturn, Neptune –CMercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

17 iClicker Question Today, the research known as SETI is conducted primarily by –Ascanning the skies for signals from alien civilizations –Bsending spacecraft to the planets –Cusing telescope to observe extrasolar planets

18 iClicker Question If we sent one of our current spacecraft to a nearby star (besides the Sun), the trip would take about –A10 years –B100 years –C1000 years –D10,000 years –D100,000 years

19 iClicker Question Scientists today are interested in searching for life on Mars because –Awe see clear evidence of a past civilization on Mars. –BMars contains frozen water ice at its polar caps. –Cevidence suggests that Mars had liquid water on its surface in the distant past.

20 iClicker Question Based on current evidence, the object in our Solar System most likely to have a deep, subsurface ocean of liquid water is –AMars –BTitan –CVenus –DEuropa –EIo

21 iClicker Question Based on the way scientists view the study of astrobiology, failure to find life on any other world would mean –Athe whole subject has been a waste of time. –Bwe must have done something wrong, since life has to exist beyond Earth –Cwe have learned important lessons about the conditions that made life on Earth possible

22 Overview of Chapter 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

23 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

24 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.

25 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.

26 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)

27 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.

28 For Next Meeting Read Chapter 2 in textbook –In general you should be reading ahead for the upcoming classes