astronomy 5 quiz
Observations show that dark matter must also be present in other galaxies (whose outer regions also orbit too fast "for their own good"—they also have flat rotation curves). Perhaps as much as _______ of the mass in our Galaxy (and many other galaxies) is not only invisible, but we do not even know what it is made of.
95%
In about 3 billion years, the Milky Way Galaxy and ___________ Galaxy will begin a long process of colliding, separating, and then coming back together to form an elliptical galaxy
Andromeda
Which of the following statements about dark matter is FALSE?
Astronomers have a pretty good idea what the dark matter is made of
Which of the following statements about the early universe (standard model of cosmology) is FALSE?
At the very beginning, the energies were so great that the universe was actually contracting for a while
Today, we believe that only a small number of elements were actually formed during the Big Bang. Which of the following was NOT one of these
Carbon
_________ is causing the expansion of the universe to accelerate; the source of this energy is not yet understood.
Dark energy
Recent observations indicate that the universe is expanding faster today than it was a few billion years ago (that the universe is accelerating). What kind of observations have led astronomers to this surprising conclusion?
Measurements of galaxy distances using Type Ia supernovae
The Sun is located in the __________.
Orion arm
The satellite that has given us the most recent and precise measurements of the characteristics of the CMB is?
Planck
The name of the supermassive black hole at the center of our Milky Way Galaxy
Sagittarius A*
The type of galaxy that sometimes has a distinct bar of stars running across the central region is
Spiral
Very low heavier-element abundance
Stellar Halo (Excludes Dark Matter)
~13 billion years
Stellar Halo (Excludes Dark Matter)
The band of light encircling the sky, which is due to the many stars and diffuse nebulae lying near the plane of the Milky Way Galaxy
The Milky Way Galaxy
Intermediate heavier-element abundance
Thick Disk
~11 bllion years
Thick Disk
1 to ~10 billion years
Thin Disk
High heavier-element abundance
Thin Disk
Local Group is the small cluster of galaxies to which our Galaxy belongs.
True
merger
a collision between galaxies (of roughly comparable size) that combine to form a single new structure
spiral galaxy
a flattened, rotating galaxy with pinwheel-like arms of interstellar material and young stars, winding out from its central bulge
starburst
a galaxy or merger of multiple galaxies that turns gas into stars much faster than usual
elliptical galaxy
a galaxy whose shape is an ellipse and that contains no conspicuous interstellar material
irregular galaxy
a galaxy without any clear symmetry or pattern; neither a spiral nor an elliptical galaxy
supercluster
a large region of space (more than 100 million light-years across) where groups and clusters of galaxies are more concentrated; a cluster of clusters of galaxies
The expansion of the universe, according to astronomers, is:
a piece of established observational evidence which any theory of cosmology must include
galactic cannibalism
a process by which a larger galaxy strips material from or completely swallows a smaller one
void
a region between clusters and superclusters of galaxies that appears relatively empty of galaxies
The reciprocal of the Hubble constant (1/H0), also known as the Hubble Time (T0) is
a rough estimate of the age of the universe
spiral arm
a spiral-shaped region, characterized by relatively dense interstellar material and young stars, that is observed in the disks of spiral galaxies
population I star
a star containing heavy elements; typically young and found in the disk
population II star
a star with very low abundance of heavy elements; found throughout the Galaxy
One of the most important observations in the history of astronomy was the one by Edwin Hubble that established that there are other galaxies, quite removed from the Milky Way. How did Hubble show this?
by observing a Cepheid variable in a nearby galaxy and using it to get the distance
evolution (of galaxies)
changes in individual galaxies over cosmic time, inferred by observing snapshots of many different galaxies at different times in their lives
slow-moving massive particles, not yet identified, that don't absorb, emit, or reflect light or other electromagnetic radiation
cold dark matter
In the "closed" universe model, the universe will end by
coming together in a "big crunch"
The assumption that, on the large scale, the universe at any given time is the same everywhere—isotropic and homogeneous
cosmological principle
The fact that different parts of the Galaxy turn at different rates, since the parts of the Galaxy follow Kepler's third law: more distant objects take longer to complete one full orbit around the center of the Galaxy
differential galactic rotation
The Hubble constant is a constant of proportionality in the law relating the velocities of remote galaxies to their ___________.
distances
Our Milky Way Galaxy is what type of galaxy?
spiral
What causes the expanding universe to decelerate in many of our cosmological models?
the mutual gravity of the galaxies pulls them together
halo
the outermost extent of our Galaxy (or another galaxy), containing a sparse distribution of stars and globular clusters in a more or less spherical distribution
The reason type I supernovae are useful to astronomers for determining distances to other galaxies is that
they are very bright, and generally reach the same peak luminosity.
The explosion of a white dwarf in a binary system that reaches a luminosity of about 4.5 × 109 LSun; it can be used to determine distances to galaxies on a large scale.
type Ia supernova
Hubble's law is a rule that the radial velocities of remote galaxies are proportional to their distances from ________.
us
According to our studies of the ages of the oldest stars and the CMB, the age of the universe must be:
13.8 billion years
Studies of the motions of the most remote globular clusters and the small galaxies that orbit our own Galaxy show that the total mass of the Galaxy is at least 2 × 1012 MSun, which is about ______ times greater than the amount of luminous matter, which astronomer have come to call dark matter.
20
The stars in the halo are old, have low abundances of elements heavier than hydrogen and helium, and have ____________ orbits randomly oriented in direction.
highly elliptical
__________ means having a consistent and even distribution of matter that is the same everywhere.
homogeneouse
___________ means having a consistent and even distribution of matter that is the same everywhere.
homogeneouse
fast-moving massive particles, not yet identified, that don't absorb, emit, or reflect light or other electromagnetic radiation.
hot dark matter
Where do you find the oldest star in the Milky Way Galaxy?
in the galactic halo
__________ means the same in all directions.
isotropic
Which of the following is pretty good evidence that the universe begin with a Big Bang?
the Cosmic Microwave Background (CMB)
nuclear bulge
the central (round) part of the Milky Way or a similar galaxy
In which model (theory) of the universe will all the galaxies eventually show a blue shift in their spectrum instead of a redshift?
the closed universe