Q&A Hero

Q: In which city is Polaris highest in the sky? A) Singapore B) Mexico City C) Denver D) Anchorage E) All the same, depending on the time of night

Q: Polaris is always directly overhead at A) the north pole. B) any location north of the equator. C) the equator.

Q: Summer and winter constellations are different because A) of the spin of the Earth about its polar axis. B) the night sky faces in opposite directions in summer and winter. C) of the tilt of the Earth's polar axis. D) the Earth is at the solar perigee in winter and apogee in summer. E) the universe is symmetric.

Q: We say we are looking back in time when we are looking at the stars because A) we see stars as they once were when their light reaches us. B) space curves, we are actually looking at the past when we look in the night sky. C) stars are emitting immense radiation, we are seeing processes that have already happened. D) Earth's atmosphere bends and distorts their light.

Q: How far is a light year? A) nearly 10 trillion km B) the distance of one Earth orbit C) 300,000 km D) All of the above

Q: Which best describes the intrinsic motion of stars? A) their circular motion across the sky in a 24-hour period B) their apparent yearly cycle around the Sun, due to Earth's revolution C) their motion relative to all other bodies D) their motion relative to Earth

Q: The North Star has very little apparent rotation in the night sky because A) it lies directly above the Earth's axis of spin. B) it rotates in the same relative orbit as Earth. C) its rate of spin directly matches Earth's. D) the Oort cloud distorts the view of the naked eye.

Q: The diurnal rotation of the stars refers to the A) apparent rotation of the celestial sphere due to the rotation of the Earth. B) movement of the stars across the sky during daytime hours. C) rate of spin of stars in their formation stage. D) particular constellations that are visible in different times of the year.

Q: What is the upper limit of stars the unaided eye can discern on a moonless night in a rural area? A) about 3000 B) about 30,000 C) about 300,000 D) about 3,000,000

Q: The Large Megllanic Cloud is A) a bright nebula within our galaxy. B) an irregular galaxy colliding with the Milky Way. C) the farthest known object visible to the naked eye in a clear night time sky. D) an unusually bright planetary nebula.

Q: Our local group is situated A) within a major supercluster. B) directly between two major superclusters. C) relatively distant from any supercluster.

Q: Our local group consists of A) 1 major galaxy. B) 2 major galaxies. C) 3 major galaxies. D) about a dozen major galaxies.

Q: Which is smaller? A) a local group B) a local supercluster

Q: Which is smallest? A) a galaxy B) a local group C) a Supercluster D) the observable universe

Q: Which is largest? A) a galaxy B) a local group C) a Supercluster D) the observable universe

Q: Compared to most stellar objects, quasars are more A) distant. B) energetic. C) puzzling. D) all of these E) none of these

Q: Most of the stars in colliding galaxies A) do not make contact with one another. B) coalesce into larger stars. C) exchange amounts of material in proportion to their masses. D) end up as binaries. E) undergo accelerated collapse.

Q: The Milky Way is A) a spiral galaxy. B) an elliptical galaxy. C) an irregular galaxy. D) a galaxy in the making. E) the remains of a galaxy that has run its life course.

Q: All of the stars we see at night with our unaided eyes are within A) 10,000 light-years, which is a small portion of our galaxy. B) 100,000 light-years, which encompasses most all of our galaxy. C) 5 million light-years, which encompasses our local group. D) 14 billion light-years, which encompasses the observable universe.

Q: The observable universe is A) the minor portion of the universe we can observe. B) the part of the universe that is within the visible electromagnetic spectrum. C) part of the universe visible to the unaided eye. D) about 100 billion light years across.

Q: A supercluster is a A) cluster of galactic clusters. B) very large local cluster. C) local cluster with at least 10,000 supergiant stars. D) local cluster with at least 500 supermassive black holes.

Q: Our local group is composed of how many galaxies? A) less than 100 B) less than 400 C) less than 1000 D) 1526

Q: Quasars are A) ancient, extremely high energy galaxies believed to have formed in the early universe. B) a conglomeration of pulsars within a galaxy. C) a conglomeration of spiral galaxies. D) white dwarfs that have undergone final collapse.

Q: An active galactic nucleus A) is a place of intense star formation. B) arises from the gigantic black hole at the center of a galaxy. C) is a supermassive supergiant star that resides at the center of larger galaxies. D) is a giant dust cloud at the center of a galaxy.

Q: A Starburst galaxy has this name because of its A) high rate of star formation. B) high rate of supernovae. C) large number of pulsars. D) large number of neutron stars.

Q: The Milky Way galaxy is A) in the process of colliding with the Magellanic Cloud galaxies. B) where Earth resides. C) a spiral galaxy. D) All of the above

Q: Elliptical galaxies A) tend to be smaller than the other types of galaxies. B) have little in the way of dust and gas. C) are thought to be former starburst galaxies. D) All of the above

Q: Galaxies are aggregations of stars, stellar dust, and gas. Their masses A) are all about the same, which is huge. B) vary greatly from one galaxy to the next. C) are small compared to blue supergiant stars. D) depend on the rate of pulsar emissions within them.

Q: One of Edwin Hubble's discoveries is that the known universe is expanding. This means that A) most all observable galaxies are moving away from each other. B) light rays bend as they near the event horizon of a black hole. C) light rays undergo acceleration as they travel vast distances. D) the mass of the universe is slowly dissipating.

Q: Describe the fate of planet Earth if the Sun were to collapse to a black hole.

Q: How does the mass of a giant star compare with the mass of the black hole it may become? How do the densities compare?

Q: If the Sun collapsed to a black hole, the time required for the Earth to orbit the collapsed Sun would A) increase. B) decrease. C) stay the same.

Q: As a star undergoes collapse, its rate of rotation A) decreases. B) increases. C) remains constant.

Q: As more and more mass falls into a black hole, the radius of its photon sphere A) increases. B) decreases. C) remains unaffected.

Q: If a star collapses to a tenth its size, gravitation at its surface increases by A) ten. B) twenty. C) one hundred. D) one thousand. E) more than one thousand.

Q: When a star collapses to half size, the gravitational field at its surface A) doubles. B) quadruples. C) increases eightfold. D) remains constant.

Q: Compared to the event horizon, the photon sphere of a black hole is A) nearer the singularity. B) farther from the singularity. C) at the same location.

Q: When a star collapses to become a black hole, its mass A) increases. B) decreases. C) remains unchanged.

Q: If the Sun collapsed to become a black hole, the Earth's gravitational attraction to it would be A) more. B) less. C) no different.

Q: A black hole is A) an empty region of space with a huge gravitational field. B) a small region that has the mass of many galaxies. C) the remains of a giant collapsed star.

Q: What determines if a star becomes a white dwarf, a neutron star, or a black hole? A) the principal factor is mass B) the principal factor is density C) the principal factor is temperature D) the principal factor is luminosity

Q: The event horizon of a black hole is A) the surface below which no matter or energy can escape. B) the surface where light becomes trapped in a circular orbit around the black hole. C) the physical surface of the black hole. D) the point in time when a black hole comes into being.

Q: A black hole has A) about the same mass as the original star from which it formed. B) infinite mass. C) about half the mass of the star from which it formed. D) a mass that widely fluctuates.

Q: A black hole is A) a region of space that is collapsed in on itself. B) the result of the collapse of supergiant star. C) likely found at the center of each spiral galaxy. D) All of the above

Q: Helium fusion within a star begins A) after all the hydrogen within the star has been depleted. B) when all carbon has been depleted. C) because of the force of gravity. D) with the expulsion of practically all hydrogen.

Q: A main sequence star begins transforming into a red giant when A) helium begins fusing. B) helium within the core begins to expand. C) contracting helium causes hydrogen to fuse. D) hydrogen starts fusing within the core.

Q: Which is the latest stage of a star? A) Helium collects within the core. B) Carbon collects within the core. C) The surface of the star expands into a red giant. D) The star contracts into a blue giant.

Q: Which is the earliest stage of a star? A) Helium collects within the core. B) Carbon collects within the core. C) The surface of the star expands into a red giant. D) The star contracts into a blue giant.

Q: A planetary nebula arises from A) the remains of a solar atmosphere. B) planetary accretion. C) a black hole. D) the gravitational attraction of interstellar dust.

Q: What happens to a star when the fusion cycle gets to the element iron?

Q: What event marks the birth of a star, and what event marks its death?

Q: Most of the atoms in the universe are thought to be A) hydrogen. B) helium. C) about equal amounts of hydrogen and helium. D) iron. E) elements unknown at present.

Q: A pulsar is likely a A) throbbing star in its death throes. B) black hole companion. C) spinning neutron star. D) binary star with a dark companion.

Q: The elements found on Earth have much to do with A) white dwarfs. B) neutron stars. C) pulsars. D) quasars. E) supernovae.

Q: Which one of these elements is normally the remnant of a supernova? A) hydrogen B) helium C) silver D) none of these

Q: A white dwarf is a former A) low-mass star. B) high-mass star. C) white giant.

Q: After our Sun burns its supply of hydrogen, it will become a A) white dwarf. B) black dwarf. C) black hole. D) red giant. E) blue giant.

Q: Metals are relatively more abundant in A) old stars. B) new stars. C) neither in particular

Q: The gold in Uncle Harry's teeth fillings originated in A) the deep interior of the Earth. B) fusion processes that date back about 5.5 billion years. C) the Big Bang. D) stars that blew up eons ago. E) Fort Knox.

Q: It is theorized that a pulsar only emits X-rays and visible light during its early history. What do you suppose is the basis of this theory? A) As the pulsar's energy dissipates, the frequency of the energy it emits drops. B) X-rays are likely the result of radioactive decay, which only can occur in a pulsar's early history. C) X-rays and visible light are both part of the electromagnetic spectrum. D) The pulsars high rate of spin produces a magnetic field that, over time, slows the pulsar down.

Q: Most of the energy during the collapse of the iron core of a supergiant star is released in the form of neutrinosnearly massless subatomic particles that rarely interact with matter. So how is it they can blow away a stars outer shells? A) Although they rarely interact with matter, the sheer number released during the collapse is enough to move most of the star's mass into surrounding space at incredibly high rates of speed. B) By creating a massive magnetic field that convulses in on itself, ripping away the stars outer shells C) When neutrinos exceed a certain speed, 22,300 km/s, they interact with matter quite effectively. D) By developing a temporary, but relatively strong positive charge

Q: Why are elements heavier than iron less abundant than those that are lighter? A) because the duration of a supernova is relatively short B) because they tend to be unstable, and easily undergo fission C) Spectral evidence suggests they are only rare here on Earth. D) This is one of the mysteries of cosmic formation that has yet to be answered.

Q: Why can't any star, no matter how massive, fuse elements heavier than iron? A) because the nucleons within iron have the least mass possible B) because elements heavier than iron have less average mass per nucleon C) It could happen, we just have not yet observed a star massive enough to do this. D) Actually, this occurs on a regular basis, which explains the great abundance of heavy elements.

Q: Supernovae are one of the most extreme events in the known universe. They are caused by A) the implosion of a white dwarf, which has run out of all its fuel. B) a supermassive supergiant star undergoing a massive nuclear chain reaction. C) the collapse of a supermassive supergiant star. D) Any of the above.

Q: Because a white dwarf is no longer burning fuel, it is more accurately described as being a A) stellar remnant. B) failed star. C) protostar. D) black elf.

Q: What will halt the collapsing Sun's core once its fuel has been exhausted? A) the inability of electrons to enter into neighboring electrons quantum state B) outward thermal pressure C) random quantum fluctuations D) the shift from fusion to fission nuclear reactions

Q: What do astronomers expect will be left at the center of our solar system once the Sun has gone through all its life stages? A) a planet sized diamond B) a red giant C) a black hole D) a wormhole

Q: What will be the predominant element within the Sun after it has died? A) helium B) nitrogen C) carbon D) phosphorous

Q: What is generally the range of a star's hydrogen burning lifetime? A) from a few million to 50 billion years B) from a few hundred thousand to 20 billion years C) from 20 billion to 100 billion years D) from 2 billion to 15 billion years

Q: What event will eventually move an average star off the main sequence of the H-R diagram? A) running out of hydrogen, causing gravitational influx, resulting in core temperatures high enough to begin fusing helium B) surface cooling due to hydrogen loss C) solar wind storms D) its drift through space due to the gravitational attraction of neighboring giant stars

Q: How is a larger star like an SUV, while a smaller star like a fuel efficient hybrid vehicle? A) The larger the star, the faster it burns fuel. B) The larger the star, the more likely it is to explode. C) The larger the star, the shorter its life span. D) Larger stars have only one source of energy.

Q: What prevents stars greater than about 100 times the Sun's mass from existing? A) The rate of thermal expansion would overcome gravitational attraction leading to explosion. B) The gravitational attraction would overcome the rate of thermal expansion leading to a black hole. C) Fusion cannot take place at these higher mass levels. D) The gaseous material of the universe is too widely dispersed to allow for the formation of stars of this mass.

Q: The determining factor in the stages a star will progress through from birth to death is its A) mass. B) temperature. C) composition. D) relative density.

Q: A star's size stabilizes when A) thermal pressure and gravitational attraction balance each other. B) the star's gravitational attraction is balanced by the gravitational attraction to neighboring stars. C) the star first ignites. D) it reaches temperatures of about 3 million K.

Q: Stars to the upper left of the Hertzsprung-Russell diagram tend to be relatively A) hot and blue. B) long lasting. C) huge. D) yellow and of average size.

Q: Stars to the upper right of the Hertzsprung-Russell diagram tend to be relatively A) hot and blue. B) long lasting. C) huge. D) yellow and of average size.

Q: Stars to the lower left of the Hertzsprung-Russell diagram tend to be relatively A) hot and blue. B) long lasting. C) huge and massive. D) yellow and of average size.

Q: Most white dwarfs A) have relatively hot surfaces. B) have relatively cool surfaces. C) evolve into black holes. D) are about as dense as their parent stars.

Q: What are the outward forces that act on a star? What are the inward forces? How do these compare?

Q: The H-R Diagram, an important tool of astronomers, relates stellar temperature to stellar A) distance. B) mass. C) color. D) density. E) luminosity.