Chapter 18 Astronomy – Flashcards

Part A The history of the universe can be divided into seven major phases. Taken together, these phases make up the cosmic evolutionary scheme—the continuous transformation of matter and energy that has led to the appearance of life and civilization on Earth. Rank the phases in the history of cosmic evolution from earliest to most recent.

Part B Somewhat surprisingly, there is not a single generally accepted definition of life. Depending on the set of criteria used to define life, some generally accepted non-living things might fulfill all of the criteria and be categorized as living. Likewise, some generally accepted living things might fail to meet all of the criteria and be classified as non-living. For example, one working definition of life requires that living things exhibit the following four characteristics. This working definition fits the easy cases of things that are obviously alive, but does not always hold up in all cases. Use these four characteristics as a working definition of life to see which generally accepted living and non-living things from the table would be considered alive based on these characteristics. They can react to their environment and can often heal themselves when damaged. They can grow by taking in nourishment from their surroundings and processing it into energy. They can reproduce, passing along some of their own characteristics to their offspring. They have the capacity for genetic change and can therefore evolve from generation to generation and adapt to a changing environment. From the descriptions and the working definition of life, determine which things do and do not exhibit these characteristics

As the mass of the central star increases, the distance to the habitable zone __________ and the size (width) of the habitable zone __________. Select from the choices in the format first blank / second blank.

Suppose that our Sun was cool enough to include Mercury in its habitable zone. Which of the following would be true in that case?

Scientists think it is very unlikely that complex and large forms of life could evolve on planets that orbit stars that are much more massive than the Sun. Why?

Part B - Habitable zones The third factor of the Drake equation is an estimate of the number of habitable planets each planetary system might contain. Two key parameters that need to be considered when determining a planet's ability to sustain life are the planet's distance from its parent star, which determines whether the planet is in the stellar habitable zone, and the parent star's distance from the galactic center, which determines if the star is in the galactic habitable zone. Consider the following sets of conditions, and sort each set according to whether it has a high or low probability of supporting life. Drag the appropriate items to their respective bins.

Currently, astronomers are observing the universe across many different regions of the electromagnetic spectrum, from gamma rays to radio waves. One of the primary issues when considering communication with potential life outside our planet is how an extraterrestrial signal would be distinguished from natural radiation sources. Sort the following source properties by whether they might be considered as originating from intelligence or simply be natural phenomena.

Part B In searching for signs of intelligence elsewhere in the universe, scientists begin with assumptions based on biological and chemical properties of Earth. They also examine how signals from Earth might appear to an observer in space. Select the statements that correctly describe what an extraterrestrial observer outside our Galaxy might see when viewing Earth.

Dinosaurs lived on Earth for a thousand times longer than human civilization has existed to date.

The development of life and intelligence on Earth are extremely unlikely if chance is the only evolutionary factor involved.

The chemical elements that form the basic molecules needed for life are found

Fossil records of early life-forms on Earth suggest that life began about

The least-well-known factor in the Drake equation is

We don't expect life on planets orbiting B-type stars because the star

NASA's Space Shuttle orbits Earth at about 17,500 mph. If it traveled to the next Sun-like star at that speed, the trip would take at least

From the data shown in Figure 18.10 in the textbook (Stellar Habitable Zones), the habitable zone surrounding a main sequence K-type star

If Figure 18.14 in the textbook (Earth's Radio Leakage) were to be redrawn for a planet spinning twice as fast, the new jagged line would be

What were the first biologically important molecules produced in the Miller-Urey experiments?

Which of the following is NOT one of the steps involved in the development of life that has been successfully performed in laboratory experiments?

If the entire history of Earth were compressed into 46 years (instead of 4.6 billion) how long ago did humans appear?

Robot probes sent to the other planets of the solar system have demonstrated that life as we know it exists on which of the following?

What is the most important piece of evidence known about Mars that suggests it once had an environment that could be supportive of life?

What is the meaning of the term extremophiles?

Which of the following objects are considered the three most likely solar system candidates for extraterrestrial life?

Which of the following is NOT one of the qualities we look for in a planet that make it a promising place to look for life?

What is the "stellar habitable zone"?

What question does the Drake equation attempt to answer?

Which term of the Drake equation is completely unknown and the hardest to determine?

Which of the following is NOT a term of the Drake equation used to calculate the number of current technological civilizations in our Galaxy?

Part A Astronomers using new space-based telescopes have found over a thousand exoplanets of all different types. Some of these are in the habitable zone around their parent star. What can we expect to find on these planets.

Part B: Would a large rocky moon orbiting a gas giant in the habitable zone be suited for life?

If we communicated with a civilization from another star, how long would a conversation with them take?

The most likely region of the radio spectrum for communication with other civilizations is in the "water hole." What part of the spectrum is this?

What is the best means we have for interstellar communication?

Why do we seek to communicate with intelligent life outside of our solar system, rather than trying to search personally or with robots?

How would Earth appear at radio wavelengths to extraterrestrial astronomers?