Astronomy I Exam 2 Sample

Transcription

1 NAME: Part I: Multiple Choice (2 points. ea.) Read carefully, choose the best answer 1. Which of the following occurs because of the orbital motion of the Earth about the Sun and cannot be accounted for in geocentric models of the solar system? (A) stellar parallax. (B) the greenhouse effect. (C) impact craters. (D) the phenomenon of day and night 2. The age of the earth is estimated at roughly: (A) 4.6 trillion years. (B) 4.6 billion years. (C) 4.6 million years. (D) less than 6 thousand years. 3. What are the two most abundant gases in the earth's atmosphere? (A) nitrogen and oxygen. (B) oxygen and carbon monoxide. (C) water vapor and argon. (D) methane and hydrogen 4. S waves (shear waves, a type of seismic wave) cannot travel through the Earth's outer core. What does this tell us about the outer core? (A) The outer core is very cold (B) The outer core is made of air (C) The outer core is liquid (D) The outer core is made of silicate rock 5. What is the origin of the Earth's magnetic field? (A) pockets of solar magnetism captured from the solar wind. (B) permanent magnetism left over from the formation of the Earth. (C) the flow of ionized gases in the Earth's upper atmosphere. (D) convection currents in the Earth's molten iron core which create an electric dynamo. 6. The process by which gravitational forces separate material of different densities within the planetary interior is called (A) Subduction. (B) Homogenization. (C) Differentiation. (D) Transvection. 7. What produces aurorae? (A) Chemical reactions in the upper atmosphere (B) Meteors (C) High energy particles trapped in Earth's magnetic field collide with atmospheric gas (D) Reflection of sunlight by high clouds 1

2 8. At which phase of the moon could lunar eclipses occur? (A) full (B) new (C) first quarter (D) second quarter 9. The Moon always faces the Earth because of (A) Tidal locking. (B) Kepler's third law. (C) Retrograde motion of the Moon's orbit. (D) Conservation of angular momentum. 10. Compared to the lunar uplands (the terrae), the lunar maria are (A) Smoother and older (B) Smoother and younger. (C) More cratered and older (D) More cratered and younger 11. Approximately how old are the oldest of the lunar samples returned to Earth by the Apollo astronauts? (A) 4.6 billion years. (B) 460 million years. (C) 46 million years. (D) 4.6 million years. 12. Consider the following hypothetical situation. A spacecraft lands on a moon of one of the planets. The moon has a smooth surface resembling that of the lunar maria. The rocks on the surface are found to be 4.5 billion years old. Why would such a finding be highly unusual? (A) Such rocks are far older than any found on the Earth's moon. (B) If the surface is that old, it should be heavily cratered. (C) The maria rocks on the Earth's moon are much older than 4.5 billion years. (D) There should not be rocks on maria. 13. Which of the following is now thought to be the most likely way in which the Moon formed? (A) fission model. (B) binary accretion model. (C) capture model. (D) giant impact model. 14. Why is Mercury difficult to observe? (A) It is very dim (B) It is always near the Sun in the sky. (C) It is usually on the other side of the Sun from the Earth. (D) setting at sunrise. 15. Which of the following objects has a surface that most resembles that of Mercury? (A) Venus (B) The Moon (C) Mars (D) Jupiter

3 16. Both the moon and Mercury have very large temperature variations between day and night. The main reason for this large variation is: (A) rocky composition. (B) distance from the sun. (C) small mass. (D) lack of atmosphere. 17. Why are there more craters on Mercury, than on Venus, Earth, and Mars? (A) More collisions with Meteors have occurred on Mercury's surface, compared with Venus, Earth, and Mars. (B) More large scale surface activity enhance the cratering effect on Mercury. (C) Less large scale surface activity preserve the existing craters on Mercury. (D) Larger volcanic eruptions have occurred on Mercury's surface, compared with Venus, Earth, and Mars 18. Which planet is most like Venus in size and mass? (A) Neptune (B) Mercury (C) Mars (D) Earth 19. Why does Venus appear featureless when viewed through a telescope? (A) it has permanent dust storms. (B) its atmosphere is so hot that shimmering distorts its image (C) it has an extremely smooth surface. (D) it has a very thick cloud layer 20. Why is the surface of Venus so hot? (A) Venus absorbs nearly all of the solar radiation that strikes it (B) Infrared radiation emitted by the surface can't escape into space (C) Frequent volcanic eruptions heat the lower atmosphere (D) The surface is heated by radioactivity in surface rocks 21. Why are there few spiral patterns (like we see in hurricanes on Earth) seen in ultraviolet images of the clouds of Venus? (A) The rotation rate of Venus is very small, so there is almost no Coriolis effect. (B) The clouds are constantly rising and falling. (C) The clouds are not made of water droplets. (D) Venus has no Moon to produce tides that make spiral patterns. 22. By observing the orbits of the two satellites of Mars, we can determine Mars' (A) diameter. (B) temperature. (C) mass. (D) moisture content.

4 23. What evidence do we have that there has been liquid water on Mars's surface in the recent past? (A) Small pools of surface water (B) Ice clouds in the atmosphere (C) Very young channels near the rims of craters (D) Observations of large quantities of subsurface ice 24. In which of the following forms can water NOT exist on Mars today? (A) lakes (B) atmospheric ice crystals (C) underground ice deposits (D) atmospheric gas 25. We see impact craters on the slopes of large Martian volcanoes. What does that tell us about the volcanoes? (A) They are billions of years old (B) They attract infalling meteoroids (C) There have never been rivers on the volcano slopes (D) They produce lava that is laid down in very thin layers 26. During some seasons the barometric pressure on Mars drops steadily for months at a time. Why? (A) gas is escaping rapidly into space. (B) enormous storms are forming around low pressure regions. (C) tides cause the atmosphere to rise and fall. (D) the atmospheric gas is solidifying on one of the polar caps. 27. Why is Mars red? (A) solar UV radiation has damaged surface materials (B) it is covered by red colored lichens and mosses (C) red light penetrates the atmosphere better than blue light (D) its soil contains highly oxidized iron compounds 28. The Jovian planets (A) all have orbits larger than the orbit of Mars. (B) are the Jupiter-like planets. (C) have atmospheres containing mostly hydrogen and helium. (D) all of the above. 29. Which of the following statements correctly describes the chemical composition of the Jovian and terrestrial planets? (A) The Jovian planets more closely resemble the Sun and stars (B) The Jovian and terrestrial planets have similar compositions (C) The Jovian planets have a higher percentage of silicon and iron than terrestrial planets (D) The terrestrial planets have more hydrogen than the Jovian planets 30. The variation between pole and equatorial rotation rates for a Jovian planet (A) is called differential rotation. (B) is evidence that the planet is fluid. (C) has never actually been observed. (D) both (A) and (B) above.

5 31. What is the conducting material that gives rise to Jupiter's magnetic field? (A) iron and nickel. (B) a salty water solution. (C) copper. (D) metallic hydrogen. 32. Which of the following planets has the lowest density? (A) Mercury. (B) Earth. (C) Mars. (D) Saturn. 33. The inner parts of Saturn's rings orbit at a faster speed than the outer parts of the rings. What does this tell us about the rings? (A) The rings are made of solid sheets of material. (B) Gravity is not the force that holds the rings in orbit about Saturn. (C) The rings are made of a myriad of independently orbiting particles. (D) The rings orbit in the direction opposite the rotation of Saturn. 34. What would happen to an asteroid that came within the Roche limit of a planet? (A) It would be ejected at twice the speed it originally had. (B) It would be destroyed by tides. (C) It would be captured and become a satellite. (D) It would be burned up in the atmosphere of the planet. 35. Why did William Herschel have to observe Uranus on more than one night before he could be sure it was a planet and not a star? (A) He had to see if it showed a full range of phases from new to full. (B) He had to see if it moved among the stars from night to night. (C) He had to see if it had satellites. (D) He had to see if it varied in brightness from night to night. 36. What is remarkable about the rotation of Uranus? (A) Its rotation period is very long (about 12 years) (B) Its rotation axis lies in its orbital plane (i.e. axis is tilted by about 90 ) (C) Its rotation axis always points at the sun (D) It does not seem to be rotating 37. How was Neptune discovered? (A) By accident, while an astronomer was looking for comets (B) It passed in front of a bright star (C) By looking at a position predicted by calculations (D) This is a trick, it has been known since antiquity 38. Trans-Neptunian Objects (A) are icy bodies beyond the orbit of Neptune (B) include Pluto and Charon (C) include Eris, which is bigger than Pluto (D) all of the above

6 39. What property of Pluto lead to its demotion from planet to dwarf planet? (A) Its non-spherical surface (B) Pluto does not dominate the space associated with its orbit. (C) Pluto is too small to be a true planet. (D) Pluto is made of ices, rather than rocks and metals 40. Which planet s satellites closely resemble asteroids? (A) Mars (B) Venus (C) Uranus (D) Pluto 41. What are the most notable surface features of Jupiter's satellite Io? (A) Volcanoes (B) Grooved ridge systems (C) Regions with high impact crater densities (D) Smooth regions produced by flows of liquid water 42. Why are the inner Galilean satellites denser than the outer ones? (A) the outer ones are made mainly of gas. (B) the inner ones contain more iron. (C) the inner ones are larger. (D) the outer ones contain more icy material. 43. Suppose a planet is orbited by a number of satellites. Which of the satellites will feel the strongest tidal forces due to the planet? (A) The rockiest satellite. (B) The farthest satellite. (C) The iciest satellite. (D) The closest satellite. 44. What is particularly noteworthy about Titan (A) It has a thick atmosphere (B) It has clouds and precipitation (C) It has lakes of liquid methane (D) all of the above 45. Most of the asteroids have orbits that lie between the orbits of (A) Mars and Jupiter (B) the Earth and Mars (C) Venus and the Earth (D) Jupiter and Saturn 46. Most meteorite solidification ages are (A) older than 10 billion years. (B) about 4.6 billion years. (C) about 4.6 million years. (D) about 4.6 thousand years.

7 47.Which of the following best describes the material that makes up the nucleus of a comet? (A) Rocky. (B) Gaseous (C) Metallic crystals. (D) Dirty ice. 48. When happens to the tail and coma of a comet after the comet passes perihelion (the point of closest approach to the sun)? (A) They disappear until the comet is far from the Sun again (B) They continue to grow until the comet passes 1 AU (C) They detach from the comet (D) They shrink 49. Impacts (A) have created craters throughout the solar system, from the inner planets, the asteroids, the moons of the gas giants to the Trans-Neptunian Objects like Pluto and Charon. (B) were much more frequent in the early history of the solar system, about 4 billion years ago. (C) have recently been directly observed happening to Jupiter, both in 1994 with the impact of comet Shoemaker-Levy 9 and in the last few weeks, as captured on camera by amateur astronomer Gerrit Kernbauer. (D) all of the above. 50. The particles which produce meteor showers come from (A) impacts of meteoroids with the moon. (B) interstellar space. (C) collisions of asteroids with each other. (D) dead comets.