ASTRONOMY / SCI 151 / UOP 151 ANSWERS

Astronomy / SCI 151 / Content QuestionsWeek 1 Content Questions
1. Name the motion that causes the seasons on Earth.
A) Rotation of Earth on its axis
B) Rotation of the Moon on its axis
C) Revolution of Earth around the Sun
D) Revolution of the Moon around Earth
E) None of the above

2. What is the phase of Earth one would see if viewing from the Moon during New Moon?
A) A ?New Earth? (Earth not seen)
B) A ?Full Earth? (Earth seen fully)
C) Earth can not be seen, since the Moon is not visible from Earth?s sky
D) A ?Crescent Earth?
E) An eclipse of Earth, since the Moon would partially be in Earth?s shadow.

3. Where in the sky would you see the North Star if you were viewing it from the equator?
A) You?d clearly see it over the North Pole
B) It would be visible but stationary directly above you
C) You?d see it towards the South Pole, but at an angle based on your latitude
D) You wouldn?t see it since it would be on the horizon
E) The North Star would rotate in a circle over your head

4. Among the celestial bodies stated below, where would you weigh the least?
A) On the Moon
B) On an asteroid
C) On Jupiter, since it is the largest planet
D) On Earth, but below sea level
E) Aboard the International Space Station (ISS)

5. Why don?t eclipses occur every month?
A) Earth?s orbit is tilted slightly to the plane of the Moon?s orbit
B) The Moon takes approximately a month to go around Earth
C) The dark side of the Moon isn?t visible from Earth
D) Eclipses are influenced directly by the laws of gravity
E) They do, but they?re not observable every time from all places on Earth

6. What causes a solar eclipse?
A) When the New Moon casts a shadow on Earth
B) When the Full Moon casts a shadow on Earth
C) When the Moon enters the shadow of Earth
D) When the Sun comes in between Earth and the Moon
E) An increased activity of sunspots, which are violent storms within the Sun

7. In which of the following cases would you not feel any weightlessness?
A) A stationary elevator on which you?re standing suddenly starts to descend
B) A roller coaster you are riding is hurtling fast towards the ground
C) You are falling during a bungee-jump
D) You are aboard an airplane at more than 35,000 feet over the Pacific Ocean
E) As an astronaut you are performing a routine space walk

8. Which observations showed Galileo that the Earth-centered theory was wrong?
A) The presence of four Galilean moons around Jupiter
B) The phases of Venus
C) The phases of the Moon
D) The fact that Earth rotates from the west to the east
E) Newton?s laws of gravity are incompatible with the Earth-centered theory

9. What is retrograde motion?
A) The motion of certain planets that orbit the Sun in a counter-clockwise fashion
B) The geosynchronous orbits of satellites around Earth
C) The apparent backwards motion of a planet that occurs at periodic intervals
D) The reverse motion of shuttles caused due to weightlessness in space
E) When Earth overtakes the slower Moon on its orbit around the Sun

10. Which of the following would fall faster to the ground, on Earth, when freely dropped at the same instant and from the same height?
A) A pebble
B) A large boulder
C) A truck
D) They?d all fall at the same time
E) It?s impossible to tell without knowing the mass of the objects being dropped

Week 2 Content Questions
1. Which is hottest?
A) Mercury
B) The Sahara desert
C) Venus
D) The core of a comet
E) The inside of your kitchen oven while cooking meat

2. Which of the following has a solid surface?
A) Jupiter
B) Saturn
C) Uranus
D) Neptune
E) None of the above

3. Venus and Earth are about the same size and mass, yet Venus has an extreme runaway greenhouse effect, while oxygen is abundant in Earth?s atmosphere. Which of the following fact explains this?
A) On Earth, the carbon dioxide dissolved in the oceans over billions of years, but on Venus it stayed in its atmosphere
B) Venus is slightly smaller than Earth, and this small difference in size has caused a tenuous atmosphere on it over billions of years
C) Venus had significantly more carbon dioxide in its atmosphere during its origin than Earth did, which served to trap more heat
D) The greenhouse effect on Venus is mainly caused by the numerous active volcanoes that spew greenhouse gases that trap heat from the Sun
E) The runaway greenhouse effect on Venus is a direct consequence of its peculiar rotation and revolution, resulting in a shorter year and a much longer day

4. If the ages of Earth and the Moon are nearly identical, why are most rocks found on the Moon so much older than Earth rocks?
A) Earth was subject to far more meteor impacts during its early geologic history that caused accumulation of newer materials on its surface
B) The Moon cooled off quicker and formed a thick lithosphere that shielded its surface from seismic and tectonic activity
C) Moon rocks, in general, are formed from softer materials that easily alter their surface features with time
D) The conjecture that Earth and the Moon are of the same age has not been verified and could actually be false
E) The presence of an atmosphere, and especially oxygen on Earth has led to the minerals inside rocks to be oxidized thus masking their true age

5. What knowledge do comets and asteroids provide to studies of the origins of our solar system?
A) Radioactive materials on these tell us our solar system?s age with greater accuracy
B) They contain materials left over from the formation of our solar system
C) Knowledge about their trajectories could warn us of future impacts with Earth
D) Their orbits tell us how they were influenced by the Sun in its formative years
E) Their combined gravitational force on the solar system influenced its formation

6. Which of the following is not a way to detect an extrasolar planet?
A) Look for an eclipse of the extrasolar ?Sun? when the planet around it passes by
B) Data relayed from spacecrafts such as Voyager and Pioneer which have reached the edges of our solar system
C) Direct images of a planet in certain cases when the parent star is not as bright
D) By the bending of the light of the planet by gravity
E) Doppler shift technique

7. Identify which of these is a plausible way of ring formation around a Jovian planet.
A) The Sun?s heat cause evaporation of parts of the Jovian planet?s surface, which settle down as rings around it
B) Millions of planetesimals around the Sun get pulled into orbit around by the gravity of a Jovian planet, and eventually cluster as a single ring
C) The ring is formed when materials from the Kuiper Belt region coalesce due to the massive gravity of the Jovian planets
D) Small moons formed in the disks of gas surrounding a Jovian planet get dismantled and give rise to the particles of the ring
E) The rings are an integral feature of most gas giant planets formed to balance out the destabilization caused by their large gravitational attraction

8. Which of the following hypothetical observations could be plausible?
A) A Jovian planet in another star system has a moon as big as Mars
B) Saturn?s core is pockmarked with impact craters and dotted with volcanoes erupting basaltic lava
C) An extrasolar Jovian planet is discovered that?s much older than ours; it doesn?t have any moons, but has a system of rings as spectacular as those of Saturn
D) Neptune?s deep blue color is not due to methane, as previously thought, but instead is due to its surface being covered with an ocean of liquid water
E) Large, active volcanoes are found on a newly discovered smaller moon orbiting Jupiter, outside the orbits of the other known moons

9. Where is the carbon dioxide that has outgassed from Earth?s volcanoes?
A) Spread across Earth?s atmosphere
B) Locked up in rocks
C) Escaped into space
D) Converted by photosynthesis to oxygen
E) Trapped in many underground crevices linked to the volcanoes

10. Most known extrasolar planets are more massive than Jupiter. Why?
A) Smaller planets are considerably rare in the universe
B) The Doppler technique usually overestimates planet masses
C) The parent stars of these extrasolar planets are also larger than the Sun
D) Current detection methods are more sensitive to larger planets
E) Nothing can currently explain this observation.

Week 4 Content Questions
1. Which of these galaxies is most likely to be the oldest?
A) A galaxy in the Local Group
B) Our own Milky Way galaxy, since it was close to the Big Bang
C) A galaxy observed at a distance of 10 billion light years
D) Since they all formed during the Big Bang, these galaxies are about the same age
E) We don?t yet have a reasonable way to estimate the ages of various galaxies

2. Why do virtually all galaxies in the universe appear to be moving away from our own?
A) We are located near where the Big Bang happened
B) We are located near the center of the universe
C) The direction of motion of the Sun in our galactic arm gives rise to this illusion
D) Observers in all galaxies experience a similar phenomenon due to the universe?s expansion
E) Most of the galaxies in the universe are traveling at great speeds away from us

3. We observe a gamma-ray burst lasting about 200 seconds from a massive black hole that is 109 solar masses, in a region of space 2 billion light years away. How long would its dangerous gamma-rays take to reach us?
A) Since these are gamma-rays, they would reach us instantaneously
B) 200 seconds
C) 1 billion years (or 109 years)
D) 2 billion years
E) 4 billion years

4. When we observe a distant galaxy whose light has traveled for 10 billion years before reaching Earth, we are seeing the galaxy as it was when the universe was:
A) 4 billion years old
B) 7 billion years old
C) 10 billion years old
D) 14 billion years old
E) The age cannot be determined because of the variable red shifts of the galaxy

5. Based on observational evidence, is it possible that dark matter doesn?t really exist?
A) No, the evidence for it is too strong to think it could be in error
B) Yes, but only if there?s something wrong with our current understanding of how gravity should work across large distances
C) No, because most of the dark matter has already been accounted for
D) Yes, but only if all the observations themselves are in error
E) No, because without the presence of dark matter, the universe would have collapsed on itself

6. The major evidence for the idea that the expansion of the universe is accelerating comes from observations of:
A) The evolution of quasars
B) White dwarf supernovae
C) Red shift of the galaxies
D) The orbital speeds of stars within galaxies
E) The amounts and distribution of dark matter and dark energy

7. What is the current temperature of the universe?
A) Absolute zero
B) A few degrees
C) A few hundred degrees
D) A few thousand degrees
E) Variable; different regions of the universe have different temperatures

8. Which of these pieces of evidence supports the idea that inflation really happened?
A) The enormous size of the observable universe
B) The average distance between galaxies in the universe
C) The large amount of dark matter that the universe contains
D) The red shifts of galaxies which prove they are moving away from one another
E) Observations of the cosmic microwave background that indicate a flat geometry for the universe

9. What is the earliest time in the universe that we can directly observe?
A) We can actually observe the Big Bang with specialized telescopes
B) A few minutes after the Big Bang
C) A few hundred thousand years after the Big Bang
D) A few hundred million years after the Big Bang
E) We cannot observe back in time; for this we?d need a time machine

10. Strong evidence for the existence of dark matter comes from observations of:
A) Frequent turbulence in Earth?s atmosphere
B) The motion of planetary bodies in our solar system
C) The rotation of the center of our galaxy, the Milky Way
D) Interactions of clusters of galaxies
E) Dark matter from recent images taken by the Hubble Space Telescope