Astronomy Chapter 6 Test Questions – Flashcards
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Suppose you view the Solar system from high above North Pole. Which of the following statements about planetary orbits must be true?
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All the planets orbit counterclockwise around the Sun.
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The terrestrial planets in our Solar System are ____.
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Mercury, Venus, Earth, and Mars
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The Jovian planets in our Solar System are _____.
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Jupiter, Saturn, Uranus, and Neptune
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Which Jovian planet does not have rings?
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All of the Jovian planets have rings
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Which moons are sometimes called the Galilean moons?
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The 4 largest moons of Jupiter: Io, Europa, Ganymede, and Callisto
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The Cassini Mission to Saturn consists of:
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an orbiter that orbits Saturn and a probe that descended to the surface of Titan.
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Which planet (besides Earth) has been visited by the largest number of robotic spacecraft?
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Mars
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Which of the following statements about Mars is NOT true?
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We could survive on Mars without spacesuits, as long as we brought oxygen in scuba tanks
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Which of the following statements about our Sun is NOT true?
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The Sun's diameter is about 5 times that of Earth
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When we say that Jovian planets contain significant amounts of hydrogen compounds, we mean all of the following chemicals except _____.
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carbon dioxide
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In essence, the nebular theory holds that _______.
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Our Solar System formed from the collapse of an interstellar cloud of gas and dust.
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According to modern science, what was the approximate chemical composition of the solar nebula?
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98 % hydrogen and helium 2% everything else
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The terrestrial planets are made almost entirely of elements heavier than hydrogen and helium. According to modern science, where did these elements come from?
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They were produced by stars that lived and died before our solar system was born
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According to our theory of solar system formation, what 3 major changes occurred in the solar nebula as it shrank in size?
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1. It got hotter. 2. Its rate of rotation increased 3. It flattened into a disk
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Which of the following types of materials can condense into what we call ice at low temperatures?
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Hydrogen compounds
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According to our present theory of solar system formation, which of the following lists the major ingredients of the solar nebula in order from most to least abundant?
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1. hydrogen and helium gas 2. hydrogen compounds 3. rock 4. metal
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What do we mean by the frost line when we discuss the formation of planets in the solar nebula?
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It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense.
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What do we mean by accretion in the context of planet formation?
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the growth of planetesimals from smaller solid particles that collided and stick together
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According to our theory of solar system formation, what are asteroids and comets?
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Leftover planetesimals that never accreted into planets
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What do we mean by the period of heavy bombardment in the context of the history of our solar system?
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the first few hundred million years after the planets formed, which is when the most impact craters were formed.
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What is the giant impact hypothesis for the origin of the moon?
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the moon formed from material blasted out of the Earth's mantle and crust by the impact of a Mars-size object
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Suppose you start with 1 kg of a radioactive substance that has a half life of 10 years. Which of the following statements will be true after 20 years pass?
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You'll have 0.25 kilograms of the radioactive substance remaining.
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According to modern scientific dating techniques, approximately how old is the solar system?
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4.5 billion years
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What is an "extrasolar planet?"
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a planet that orbits a star that is not our own Sun
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In essence, the Kepler misison is searching for extrasolar planets by _____
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monitoring stars for slight dimming that might occur as unseen planets pass in front of them.
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The planet in our solar system with the highest average surface temperature is _______.
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Venus
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Which of the following lists planets in correct order from closest to farthest from Sun?
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Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
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Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is ___.
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much larger
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How is Einstein's famous equation E=mc2, important in understanding the Sun?
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the Sun generates energy to shine by losing 4 million tons of mass each second
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In what way is Venus most similiar to Earth?
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Both planets are nearly the same size
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Imagine that an alien spaceship crashed onto Earth. Which statement would most likely be true?
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It would crash into the ocean
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Which of the following statements about the recently discovered object Eris is NOT true?
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It is thought to be an example of a new class of object
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Mars has two moons that are most similiar in character to
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small asteroids
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Which planet listed below has the most extreme seasons?
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Uranus
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In what way is Pluto more like a comet than a planet?
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It is made of mostly rock and ice
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Which of the following is NOT a major pattern of motion in the solar system?
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Nearly all comets orbit the Sun in same direction and roughly the same plane
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Which of the following is NOT a major difference between the terrestrial and jovian planets in our solar system?
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Terrestrial planets contain large quantities of ice and jovian planets do not
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The following statements are all true. Which one counts as an "exception to the rule" in being unusual for the solar system?
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The diameter of Earth's moon is about 1/4 that of Earth.
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About 2% of our solar nebula consisted of elements besides hydrogen and helium. However the very first generation of star systems in the universe probably consisted of only hydrogen and helium. Which of the following statements is most likely to have been true about these first generation star systems?
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There were no comet or asteroids in these first-generation star systems.
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According to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size?
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the law of conservation of angular momentum
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According to our theory of solar system formation, which law best explains why the central regions of the solar nebula got hotter as the nebula shrank in size?
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the law of conservation of energy
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According to our present theory of solar system formation, which of the following best explains why the solar nebula ended up with a disk shape as it collapsed?
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It flattened as a natural consequence of collisions between particles in the nebula.
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What is the primary basis upon which we divide the ingredients of the solar nebula into four categories (hydrogen/helium, hydrogen compound, rock, metal)?
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the temperatures at which various metals will condense from gaseous form to solid form.
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According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and jovian planets is NOT true?
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The jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal.
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Many meteorites appear to have formed very early in the solar system's history. How do these meteorites support our theory about how the terrestrial planets formed?
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The meteorites appearance and composition is just what we'd expect if metal and rock condensed and accreted as our theory suggests.
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According to present understanding, which of the following statements about the solar wind is NOT true?
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It is even stronger today than when the Sun was young.
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According to our present theory of solar system formation, why were solid planetesimals able to grow larger in the outer solar system than in the inner solar system?
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Because only metal and rock could condense in the inner solar system, while ice also condensed in the outer solar system.
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According to our present theory of solar system formation, how did Earth end up with enough water to make oceans?
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The water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars.
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According to our basic scenario of solar system formation, why do the jovian planets have numerous large moons?
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As the growing jovian planets captured gas from the solar nebula, the gas formed swirling disks around them, and moons formed from condensation accretion within these disks.
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Which of the following is NOT evidence supporting the idea that our moon formed as a result of a giant impact?
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The Pacific Ocean appears to be a large crater- probably the one made by the giant impact.
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Why are terrestrial planets denser than jovian planets?
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Only dense materials could condense in the inner solar system
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Suppose you find a rock that contains 10 micrograms of radioactive potassium-40, which has a half-life of 1.25 billion years. By measuring the amount of its decay product (argon-40) present in the rock, you conclude that there must have been 80 micrograms of potassium-40 when the rock solidified. How old is the rock?
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3.75 billion years
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How do scientists determine the age of the solar system?
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Radiometric dating of meteorites
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Which of the following statements is NOT true about the planets so far discovered around other stars?
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Photographs reveal that most of them have atmospheres much like that of Jupiter.
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Which new idea has been added into our theory of solar system formation as a result of the discoveries of extrasolar planets?
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Planets can migrate from the orbits in which they are born.
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You observe a star very similar to our own Sun in size and mass. This stars moves very slightly back and forth in the sky once every 4 months, and you attribute this motion to the effect of an orbiting planet. What can you conclude about the orbiting planet?
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The planet must be closer to the star than Earth is to the Sun.
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The region of our solar system between Mercury and Mars has very few asteroids, while the region between Mars and Jupiter has many asteroids. Based on what you have learned, what is the most likely explanation for the lack of asteroids between Mercury and Mars?
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There were very few planetary leftovers in this region, because most of the solid material was accreted by the terrestrial planets as teh planets formed.
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Based on everything you have learned about the formation of our solar system, which of the following statements is probably NOT true?
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Only a tiny percentage of stars are surrounded by spinning disks of gas during their formation.
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What is the Sun mostly made of?
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Hydrogen and Helium Gas
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What is Mercury made of?
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metal and rocky composition
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Does Jupiter have a solid surface?
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No
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What are the names of Jupiter's four Galilean moons?
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Io Europa Ganymede Callisto
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What are the rings of Saturn made of?
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tiny chunks of ice and rock... each particle orbits like a tiny moon
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What is Uranus made of?
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Hydrogen and Helium gas Hydrogen compounds
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What are some examples of hydrogen compounds?
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Ammonia Water Methane
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Motion of large bodies:
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All large bodies in solar system orbit in the same direction (counter-clockwise) and in many the same plane.
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What are the two major planet types?
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Terrestrial and Jovian
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Terrestrial planets are ______.
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Rocky, relatively small, close to Sun
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Jovian planets are ___________.
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gaseous, larger, and farther away from the Sun
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What are some notable "exceptions to the rule"
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Earth's huge moon Uranus tilted
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What theory best explains solar system formation?
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nebular theory: our solar system formed from a giant cloud of gas
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Galactic Recycling:
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elements that make planets were made in stars and then recycled through interstellar space... There is evidence from other gas clouds
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Conservation of Angular Momentum:
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something shrinking in size is going to rotate faster... (remember the figure skater)
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Flattening:
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collisions between particles in cloud caused it to flatten into a disk
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Conservation of Energy:
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gravity causes the cloud to contract as the cloud heats up
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Frost line:
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Inside of the frost line is too hot for hydrogen compounds to form ice. Outside of the frost line it is cold enough for ices to form, but still have rock as well.
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Formation of terrestrial planets
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Small particles of rock/metal were present inside the frost line... planetesimals of rock and metal built up.. They collided... Gravity caused the planetesimals to build into terrestrial planets by the process of accretion
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Formation of Jovian planets
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Ice could also form small particles outside the frost line... Jovian planets are larger because they are made of rock and ice. Gravity pulls in Hydrogen/Helium gas.
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Asteroid and Comet formation:
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leftover from accretion.. Rocky asteroids formed inside the frost line Icy comets formed outside the frost line
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Heavy bombardment:
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leftover planetesimals bombarded other objects in late stages of solar system formation.. happened on Earth and moon
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Origin of Earth's water...
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Water may have come from icy planetesimals from outer solar system.
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Giant impacts can explain exceptions.
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Uranus tilted and large moon on Earth possibly because of giant impacts?
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Radioactive Decay:
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Some isotopes decay into other nuclei Potassium to Argon
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Half-life:
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time for half the nuclei in a substance to decay
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Dating the solar system:
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Average 4.6 billion years ago Age dating of meteorites that are unchanged since they condensed and accreted
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How do we find planets around other stars?
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1. Direct: pictures or spectra of the planets themselves 2. Indirect: Measurements of stellar properties revealing the effects of orbiting planets
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Gravitational Tugs
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Sun and Jupiter orbit around their common center of mass Sun wobbles around center of mass with the same period as Jupiter.
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Astrometric Technique
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detect planets by measuring change in a star's position in the sky... This is difficult because the stars don't change very much
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Doppler technique
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Objects toward us: blue Objects away from us: red Much easier to measure because it doesn't get blurred by the atmosphere
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Transits and Eclipses
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Transit: Planet moves in front of a star Eclipse: Light is dimmer
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Direct detection
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concentrating or eliminating bright starlight are enabling direct detection of planets
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What happens in a gravitational encounter that allows the orbit to move inward
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transfers energy and angular momentum to another object
