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extrasolar planet

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a planet that orbits a star other than our Sun

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habitable planet

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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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geocentric view of the universe

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the ancient idea that Earth resided at the center of the universe

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According to current scientific understanding, life on Earth

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Arose quite soon after conditions allowed it;

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The correct order for the eight official planets in our solar system, from closest to farthest from the Sun,

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Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune My very educated mother just served us nachos

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Today, the research known as SETI is conducted primarily by

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scanning the skies for signals from alien civilizations;

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If we sent one of our current spacecraft to a nearby star (not the Sun), the trip would take about

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100,000 years

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Scientists today are interested in searching for life on Mars because

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evidence suggests that Mars had liquid water on its surface in the distant past.

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Based on current evidence, the object in our solar system most likely to have a deep, subsurface ocean of liquid water is

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Europa

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Based on the way scientists view the study of astrobiology, failure to find life on any other world would mean

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we have learned important lessons about the conditions thatmade life on Earth possible.

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Observed facts

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Observed facts are agreed upon by everyone. They are not subject to dispute.

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The textbook prominently displays three lines of evidence that give us at least some reason to think that biology may be common in the universe (these and two additional lines of evidence were mentioned in class). Briefly list the three pieces of evidence displayed in the textbook. (see Figure 1.3)

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1) Evidence exists that organic molecules form easily and naturally, 2) Evidence exists that Earth life can survive under a wide range of conditions, 3) Evidence exists that life appeared early in the history of the Earth.

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In the Greek geocentric model, the apparent retrograde motion of a planet occurs when

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the planet actually goes backward in its orbit around Earth

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The motion of planets in the Ptolemaic model of the Universe can be described as

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small circles, the centers of which move in a larger circle about the Earth

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Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law,

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Earth travels faster in its orbit around the Sun in January than in July

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Kepler's third law predicts the fact that

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Jupiter completes an orbit around the Sun in less time than Saturn

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Tycho Brahe's contribution to astronomy included

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collecting data that enabled Kepler to discover the laws of planetary motion

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Galileo's contribution to astronomy included

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making observations and conducting experiments that dispelled scientific objections to the Sun-centered model

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Which of the following is not true about scientific progress? (a) Science progresses through the creation and testing of models of nature (b) Science advances only through strict application of the scientific method (c) Science avoids explanations that invoke the supernatural

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B

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How did the Copernican revolution alter perceptions of the ancient Greek debate over extraterrestrial life? (a) It showed that Aristotle's argument for a unique Earth was incorrect (b) It showed that the atomists were correct in their belief in an infinite cosmos (c) It proved that extraterrestrial life must really exist

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A

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The Law of Orbits

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All planets move in elliptical orbits, with the sun at one focus.

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The Law of Areas

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Planets move faster in their orbit the closer they are to the Sun.

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The Law of Periods

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Planets on larger orbits take longer to complete an orbit than planets smaller orbits.

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Which of the following is inconsistent with Kepler's Laws? a) A planet in a circular orbit. b) Planet A, in an orbit approximately twice the size of Planet B's orbit, has an orbital period that is slightly less than three times as long as that of the Planet B. c) Planets having their largest orbital velocity when they are farthest from the sun

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C

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While the heliocentric model of Copernicus had many advantages over the Ptolemaic model, it suffered from the assumption that the

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planets moved in perfect circles about the Sun

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The revolution epitomized by Copernicus that still dominates scientific thought could be described as having moved our view of mankind's place in the universe from

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a special place to an average place.

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Based upon our current understanding, approximately how old is the universe?

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14 billion years

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Compared to your mass here on Earth, your mass out in the space between the stars would be

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the same (mass measures the amount of material)

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What causes the apparent retrograde motion of a planet in the heliocentric model of the Universe?

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differences in the rates at which the Earth and the planet orbit the sun

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Ptolemy's model for the universe contains the assumption that the centers of the epicycles of the inferior planets, Mercury and Venus, lie on a line between the Earth and the Sun. This was to explain the observation that

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these planets are always observed fairly close to the Sun in the sky.

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The orbit of Planet X has a semimajor axis a = 1.0 Astronomical Units (A.U.) In view of Kepler's Laws and how the A.U. is defined, how does the orbital period of planet X compare with that of the Earth?

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it is the same (Kepler's 3rd law gives a relationship between the orbital period of a planet and its semimajor axis. Both of these planets have the same semimajor axis and therefore the same orbital period

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The Milky Way Galaxy is

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a collection of more than 100 billion stars, of which our Sun is one.

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The spectrum of light coming from an astronomical object can give us information about the object's (a) composition (b) temperature (c) velocity (d) choices B and C (e) all of the above

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E

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Which of the following sequence of electromagnetic radiations is in order of increasing energy? (a) radio, infrared, UV, gamma ray (b) gamma ray, UV, radio, microwave (c) X-ray, visible, infrared, radio (d) UV, infrared, visible, microwave

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A

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When we say the universe is expanding, we mean that

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the average distance between galaxies is growing with time.

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According to observations, the overall chemical composition of our solar system and other similar star systems is approximately

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98% hydrogen and helium, 2% all other elements combined.

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The age of our solar system is about

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one-third of the age of the universe.

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How many of the planets orbit the Sun in the same direction that Earth does? (a) a few (b) most (c) all

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C

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Which of the following correctly describes the law of conservation of energy? a) Energy can change between many different forms, such as potential, kinetic, and thermal, but it is ultimately destroyed. b) It is not really possible for an object to gain or lose potential energy, because energy cannot be destroyed. c) The total quantity of energy in the universe never changes. d) The fact that you can fuse hydrogen into helium to produce energy means that helium can be turned into hydrogen to produce energy. e) An object always has the same amount of energy.

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C

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While all nitrogen atoms have seven protons, some nitrogen atoms have seven neutrons and some have eight neutrons. These two forms of nitrogen are

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isotopes of each other.

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What does temperature measure?

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the average kinetic energy of particles in a substance

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The amount of gravitational potential energy released as an object falls depends on

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its mass and the distance it falls.

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What is the natural state of motion for an object?

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to maintain its current motion unless acted upon by an external force

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A tourist spaceship is coasting with its engines off, halfway along on a weeklong cruise to the Moon. A bowling ball and a paper bag are carefully placed next to each other outside of the airlock of the ship. After ten minutes, a) both objects are still moving together alongside the spaceship. b) the bowling ball is still moving alongside the spaceship, but the paper bag has been left far behind. c) both objects are far behind the spaceship. d) the bowling ball is falling back towards Earth, while the paper bag is still coasting alongside the spaceship.

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A

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What happens to thermal radiation (a continuous spectrum) if you make the source hotter? A) More energy comes out at all wavelengths B) The peak of the spectrum-energy curve (the wavelength at which most energy is emitted) shifts redward C) The peak of the spectrum-energy curve shifts blueward D) A and B E) A and C

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E

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Which of the following defines the FUNDAMENTAL DIFFERENCE between two different chemical elements (such as oxygen and carbon)?

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They have different numbers of protons in their nucleus.

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Pam accidentally drops her purse. As the purse falls towards the Earth, the Earth "falls" (by a very small amount) towards her purse. True or False

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true

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What causes light from a star to be Doppler-shifted?

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the speed of the star toward or away from us

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Consider the statement "There's no gravity in space." This statement is true or false

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false

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Suppose you visited another planet that was somewhat smaller than the Earth

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Your mass would be the same as on Earth, but your weight would be different.

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What do we mean by the expression "we are star stuff"?

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In the early universe only hydrogen and helium existed. The more massive elements we are made of were all created by nuclear fusion in stars.

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A rock's type (igneous, metamorphic, or sedimentary) tells us

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how it was made

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To learn a rock's age, we must

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measure the ratios of different isotopes within it - what is the ratio of a daughter isotope to its parent isotope?

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Radiometric dating of rocks, based upon measuring the proportions of radioactive isotopes and their decay products within these rocks, now allows us to determine Earth's age to an accuracy of about

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20 million years

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Earth's oceans are thought to have principally formed (a) during the late stages of accretion as water ice collected on the surface (b) from water vapor outgassed by volcanoes - some water may also have arrived from comets (c) when Earth underwent differentiation

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B

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We learn about the heavy bombardment by studying (a) craters and rocks from the Moon (b) zircon mineral grains (c) Earth's oldest igneous rocks

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A

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Earth has retained a lot of its initial internal heat primarily because of its

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relatively large size - larger planets cool slower than small planets. The earth is the largest of the Terrestrial planets

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Plate tectonics is best described as a process that

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recycles rock between Earth's surface and upper mantle - chapter 4 has a nice overview

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Most of the Earth's carbon dioxide

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has dissolved in the oceans and is locked up in sedimentary carbonate rocks like limestone

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Geological processes on the Earth's surface owe their origins to

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the Earth's internal heat- stresses between the lithosphere and the upper mantle are responsible for geological processes. These stresses are the results of motions in the upper mantle stemming from convection that push the lithosphere in different directions.

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Why did the solar nebula heat up as it collapsed?

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As the cloud shrank, its gravitational potential energy was converted to kinetic energy of the gas composing the nebula. - conservation of energy, in this case potential energy into kinetic energy

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How do astronomers account for the fact that all the planets orbit the Sun in the same direction and in nearly the same plane?

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The laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk. Since the planets formed out of material orbiting the sun in roughly the same plane the planets built from this material shared the same motions.

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. Smaller worlds are more prone than large worlds to losing their atmosphere because they

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have weaker gravities - Weaker gravities lead to lower escape velocities. Gas molecules that make up an atmosphere are in motion due to the temperature of the gas. If a molecule is moving faster than escape velocity it can escape from the planet. This leads to the slow escape of the atmospheres of lower mass planets.

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Briefly describe the mechanism by which the greenhouse effect warms a planet. What are the most common greenhouse gases?

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Surface of planet absorbs visible light coming from the sun. The energy of this light heats the surface of the planet. The surface emits thermal radiation that serves to cool the surface (if the surface didn't lose energy by this means, but still continued to absorb radiative energy from the Sun, its temperature would rise without any limits). Thermal radiation from the planet's surface is in the infrared. Certain gasses, referred to as greenhouse gasses, absorb infrared radiation and thus trap energy and thus heat the lower atmosphere.

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Briefly summarize three key ways in which geology is critically important to Earth's longterm habitability.

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Volcanic activity releases gases trapped in Earth's interior. These gases were the original source of Earth's atmosphere and oceans. Outgassing continues to this day, slowly replacing atmospheric gasses lost to space. Earth's long-term climate is remarkably stable because of feedback processes that tend to counter any warming or cooling that occurs. Plate tectonics plays a fundamental in this feedback process via the carbon dioxide cycle, which naturally regulates the strength of Earth's greenhouse effect. Geological activity created Earth's magnetic field. This field shields Earth's atmosphere from the energetic particles of the solar wind. Without this shielding, it's likely that a significant portion of our planet's atmosphere would by now have been stripped away into space.

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