Chapter 1 Review Questions

People have long been interested in life beyond Earth. What is different today that makes this possibility seem scientifically reasonable?

1. New discoveries in both planetary science and biology make it seem plausible that simpler life (microbes) might exist on other planets and moons of the solar system 2. We've recently gained concrete evidence telling us that the universe is full of planets as well as stars, which means there are more places that we can potentially search for life. 3. Advances in both scientific understanding and technology now make it possible to study the question of life in the universe through established techniques of science

What do we mean by astrobiology? What are the major areas of research in astrobiology?

Astrobiology invokes the combination of astronomy (study of the universe) and biology (study of life) to mean "the study of life in the universe" 1. Studying the conditions conducive to the origin and ongoing existence of life 2. Looking for such conditions on other planets in our solar system and around other stars 3. Looking for the actual occurrence of life elsewhere

Why are scientists interested in the possibility of life beyond Earth?

Discovery of any kind of life beyond Earth would forever change our perspective of how we fit into the universe as a whole, and would teach us more about life here on Earth as well

What are extrasolar planets? In what way does their discovery make it seem more reasonable to imagine finding life elsewhere?

Extrasolar planets are planets orbiting stars other than our Sun. Due to the number of extrasolar planets that have been discovered it seems reasonable that life -and possibly even civilizations- could exist on at least some of these planets or their moons.

What do we mean by a geocentric universe? In general terms, contrast a geocentric view of the universe with our modern view of the universe.

Geocentric universe refers to the idea that Earth was the center of the universe and the Sun and planets were orbiting us. This view led people to believe that there was no reason to think that stars had planets of their own and therefore no life. We now realize that Earth is is one tiny world orbiting an ordinary star in a vast cosmos and there is the possibility for life on other worlds.

What do we mean by a habitable world? Does a habitable world necessarily have life?

Habitable worlds have the ingredients and conditions necessary for life. No, habitable worlds refer to environmental conditions where life could survive, not whether it actually harbors life.

What do we mean by the "universality" of physics and chemistry? Although we don't know yet whether biology is similarly universal, what evidence makes it seem that it might be?

It means that the universe operates by the same laws of physics and chemistry. Evidence that organic molecules form easily and naturally + Evidence that life appeared early in the history of the Earth + Evidence that Earth can survive under a wide range of conditions

Besides Earth, what worlds in our solar system seem most likely to have life? Why?

Mars (evidence that once had flowing water and significant amounts of water ice, most promising place) Jupiter's moons: Europa (evidence of subsurface ocean) Ganymede (evidence of subsurface oceans, less strong) Callisto (evidence of subsurface oceans, less strong) Saturn's moons: Titan (thick atmosphere and lakes of liquid methane) Enceladus (evidence of subsurface ocean)

Could we actually detect life on an extrasolar planet and moon with our current technology? Explain

No, due to the distance we would great leaps in technology to have any hope of sending a spacecraft to study their planets up close. Right now it would take close to 100,000 years to reach. We can only use telescopic searches, which require certain conditions to detect extrasolar planets.

What is the search for extraterrestrial intelligence (SETI)?

SETI focuses on the search for signals from alien civilizations