,Chapter 01: The Universe, Stars, and New Chemical Elements
True/False
1. At the end of the nineteenth century, Henrietta Leavitt studied a special type of star whose
brightness seems to vary in a regular pattern. These were known as Cepheid variables.
Answer: True
Page: 16
Explanation: At the end of the nineteenth century Henrietta Leavitt, an American astronomer,
studied a special type of star whose brightness seems to vary in a regular pattern. These were
known as Cepheid variables, after the constellation of Cepheus in which they were first
detected.
2. Red-shifted objects were those remote objects in the universe that seemed to be moving
toward the Earth.
Answer: False
Page: 17
Explanation: Most remote objects in the universe seemed to be red-shifted. In other words,
they seemed to be moving away from the Earth.
3. The big bang theory had no explanation for the source of cosmic background radiation
(CBR). The steady state theory, however, predicted it.
Answer: False
Page: 20
Explanation: The steady state theory had no way of explaining the source of CBR. But the
big bang theory predicted it.
4. The process by which protons smash together to form helium nuclei is known as fission.
Answer: False
Page: 23
Explanation: The process by which protons smash together to form helium nuclei is known as
fusion. As protons fuse, a tiny amount of their matter is converted into a lot of energy.
5. The Hertzprung–Russell (H–R) diagram is a graph that plots the real brightness of each
star against its surface temperature.
Answer: True
Page: 26
Explanation: In 1910, a Danish astronomer, Ejnar Hertzsprung, and an American astronomer,
Henry Russell, found a way of distilling the rapidly accumulating information about stars in a
way that began to explain a lot about the life cycles of stars. They assembled information
about many different stars into a simple graph. On one axis they plotted the real brightness of
each star; and on the other they showed its surface temperature. The graph they produced is
known as a Hertzprung–Russell (H–R) diagram.
Multiple Choice
1. _____ is the change in the apparent relationship between two fixed objects caused by the
movement of an observer.
A. Fusion
,B. Parallax
C. Red shift
D. The Doppler effect
Answer: B
Page: 15
Explanation: Measuring the distance to the stars is a subtle and complex problem. The
ancient Greeks already knew in principle how to do it—through the use of parallax: the
change in the apparent relationship between two fixed objects caused by the movement of the
observer. Parallax depends on the fact that as the observer moves, objects in the middle
distance (such as a nearby star) seem to move against objects that are farther away (such as
more remote stars or galaxies).
2. _____ are formed when stars are sucked into the huge black holes that seem to lie at the
center of all galaxies.
A. Quasars
B. Cepheid variables
C. Red giants
D. Spectroscopes
Answer: A
Page: 21
Explanation: Quasar stands for “quasi-stellar radio source”; quasars form as stars are sucked
into the huge black holes that seem to lie at the center of all galaxies.
3. _____ acts as a sort of antigravity, driving things apart rather than pulling them together.
A. Plasma energy
B. Dark matter
C. Atomic matter
D. Dark energy
Answer: D
Page: 21
Explanation: In the late 1990s it became apparent that the rate of expansion of the universe is
accelerating, and most cosmologists believe that this acceleration is driven by a new form of
energy, known as dark energy, which acts as a sort of antigravity, driving things apart rather
than pulling them together.
4. Hydrogen deuterium weighs about twice as much as a normal atom of hydrogen because:
A. it has an atomic number of 92.
B. it contains 6 protons and 8 neutrons.
C. it also contains a neutron in its nucleus.
D. its neutron weighs twice as much as its proton.
Answer: C
Page: 26
Explanation: A tiny number of hydrogen atoms (roughly 0.02 percent) also have a neutron in
their nucleus. This form is called hydrogen deuterium. It weighs about twice as much as a
normal atom of hydrogen because neutrons have about the same mass as a proton. Chemists
call such deviant forms of atoms isotopes.
5. In _____ bonds, almost all atoms lose electrons from their outer shells, and a great number
of unattached electrons flow through and between the individual atoms.
A. hydrogen
, B. metallic
C. ionic
D. covalent
Answer: B
Page: 30
Explanation: In metallic bonds, the bonds that hold most metals together, almost all atoms
lose electrons from their outer shells, and hordes of unattached electrons flow through and
between the individual atoms. Because each atom has lost an electron, it has a slight positive
charge, so it is attracted to the sea of electrons flowing around it.
Essay
1. While most astronomers and cosmologists today accept that the big bang theory offers a
reasonably accurate account of the origin of the universe, what are the problems with big
bang cosmology?
The big bang theory is far from perfect. One of the most striking anomalies, and the one that
is most likely to generate revisions in the near future, is the existence of dark matter and dark
energy. These are forms of matter and energy that can be detected but not yet understood.
Astronomers first realized that there must be much more matter than humans can see when
studying the movements of stars in galaxies. Using the laws of gravity, it is possible to
estimate how fast stars should be orbiting large galaxies. The actual movements of stars
suggest that there must be perhaps 20 times as much mass as astronomers can actually detect.
Some of that mass consists of dark matter. In addition, in the late 1990s it became apparent
that the rate of expansion of the universe is accelerating, and most cosmologists believe that
this acceleration is driven by a new form of energy, known as dark energy, which acts as a
sort of antigravity, driving things apart rather than pulling them together.
Dark energy makes up about 70 percent of the mass of the universe. Because dark energy is
linked to the amount of space that exists, this is a form of energy whose importance will
increase as the universe expands. Indeed, it seems that the rate of expansion of the universe
began to accelerate, due to the increasing power of dark energy, about 9 billion years after the
big bang, at about the time the Earth was formed. Dark matter accounts for another 25
percent of the mass of the universe. The remaining 4 to 5 percent is made up of atomic
matter. Most atomic matter is in the form of hydrogen and helium and only about 1 to 2
percent consists of heavier chemical elements from carbon to uranium. But even most atomic
matter is invisible, so less than 1 percent of the matter in the universe can actually be
detected. Until the true nature of dark matter and energy is explained, a question mark will
continue to hover over the entire big bang theory.
However, astronomers and cosmologists are optimistic that experiments such as the Large
Hadron Collider (LHC) may soon offer some answers. The LHC has discovered what appears
to be the Higgs boson. As it begins to operate at even higher energy levels, many hope it will
discover other forms of energy and matter that can help explain what dark energy and matter
really consist of.
Page: 21-22
