Astronomy Chapter 1
The number 123,000 written in scientific notation is
1.23 × 105
What is the approximate number of stars in the Milky Way?
10 Billion
If the diameter of the Milky Way is approximately 100,000 light-years, then our galaxy is _________ times larger than our Solar System. For reference, Pluto's orbit has an approximate diameter of 80 astronomical units (AU).
10^8
If you compared the diameter of Earth, which is 13,000 km, to 1 second, then what unit of time would be equivalent to the size of the Milky Way, whose diameter is 1021 m, and what significant milestone would this time correspond to in our evolution?
2 million years, the length of time humans have existed on Earth
The distance to the nearest large spiral galaxy, the Andromeda Galaxy, is 2.4 × 1022 m. How long does it take light to travel from Andromeda to us?
2.5 trillion years
The speed of light is approximately
300k Kms/hr
If the radius of circle B is twice the radius of circle A, and the area of a circle is proportional to the radius squared (A ∝ r2), then the ratio of the area of circle B to that of circle A is
4
After the Sun, the next nearest star to us is approximately _________ away.
4 light-years
One of the nearest stars is Alpha Centauri, whose distance is 4.4 light-years. The time it takes light to travel from Alpha Centauri to us is
4.4 Light years
One of the nearest stars is Alpha Centauri, whose distance is 4.2 × 1016 m. How long does it take light to travel from Alpha Centauri to us?
4.4 years
The distance to the center of the Laniakea cluster of galaxies is 5 × 1023 m. How long does it take light to travel from these galaxies to us?
54 Million Years
If the speed of light is 3 × 105 km/s and 1 km = 0.62 mile, what is the speed of light in miles per hour (mph)?
670 million mph
If an event were to take place on the Sun, how long would it take for the light it generates to reach us?
8 Minutes
The average distance between Earth and the Sun is 1.5 × 1011 m, and light from the Sun takes approximately _________ to reach Earth.
8 Minutes
Which of the following is false? A scientific theory is an undisputed fact. If continual testing of a hypothesis shows it to be valid, it may become an accepted theory. A hypothesis must always have one or more testable predictions. A scientific theory may eventually be proven wrong when scientists acquire new data.
A
The figure below shows the night sky as it appears for an observer in the United States at the same time of the night but at four different seasons of the year. Which conclusion below is not reasonable based on these observations?
A good time to plant crops would be when the constellation Sagittarius is directly overhead.
The time it takes light to cross Neptune's orbit is closest to which of the following?
A night's sleep
The word astronomy means
A"to study the stars."
Describe how talking about time can give us a feeling for distance.
ANS: If speed is constant, a difference in time is directly related to a difference in distance. A time difference is easier to conceptualize.
Albert Einstein is best known for his revolutionary theory of
Albert Einstein is best known for his revolutionary theory of
Which presently observed element or isotope was not produced in appreciable amounts in the very early universe shortly after the Big Bang?
Carbon
A.The Local Group is a member of the Laniakea Supercluster, which contains thousands of galaxies. B.The Local Group contains two large spiral galaxies and a few dozen dwarf galaxies. C.Our Solar System has eight classical planets. D.The Milky Way Galaxy contains approximately 100 million stars. E.The Laniakea Supercluster is one of many superclusters in the universe. Which One is false?
D
The majority of the mass in our universe is made up of
Dark Matter
A light-hour is a measure of
Distance
A light-year is a unit commonly used in astronomy as a measure of
Distance
According to the figure below, if you were to specify your address in the universe, listing your membership from the smallest to largest physical structures, it would be
Earth, Solar System, Milky Way, Local Group, Laniakea Supercluster, the universe.
The number of planets in our Solar System is
Eight
The early universe was composed mainly of which two elements?
Hydrogen and Helium
If one thinks about the distance between Earth and the Moon, 384,400 km, approximately how much of that distance would Saturn and its rings take up?
Less than half the distance
In the scientific method, if an observation does not support the hypothesis, what possible actions should happen next?
Make more observations. Choose a new hypothesis or revise the current one.
In science an idea that cannot be tested is
Not a Scientific Idea
_________ is the idea that the simplest explanation for a phenomenon is usually the correct one.
Occam's Razor
f you have a stuffy nose, a fever, chills, and body aches and a doctor treats you for the flu rather than four separate diseases that account for each of your symptoms, this is an application of
Occam's razor
The figure below measures distances in the amount of time it takes light to travel. If the circumference of Earth is a snap of your fingers (1/7 second), the diameter of the Solar System is approximately equal to
The Length Of A work Day
Why might the universe be described as a sort of "time machine"? SA2Describe how talking about time can give us a feeling for distance.
The finite speed of light means that objects observed at larger distances are observed as they existed further in the past.
Milky Way is the name of
The galaxy in which we live in
What is the Local Group?
The group of a dozen or so galaxies including the Milky Way that are within a few million light-years of each other.
A scientific principle is
a detailed description in terms of known physical laws or theories.
A theoretical model is
a detailed description in terms of known physical laws or theories.
According to the figure below, Earth is located approximately
about halfway out from the center of the Milky Way.
A hypothesis may become a theory
after many repeated attempts to falsify it fail.
When you see a pattern in nature, it is usually evidence of
an underlying physical law.
One of the central assumptions in astronomy is that the physical laws of nature
are the same everywhere in the universe.
The study of whether or not life exists elsewhere in the Solar System and beyond is called
astrobiology.
Our universe is approximately 13.7 _________ years old.
billion
A hypothesis is an idea that is
falsifiable with current technology only. potentially falsifiable with future technology.
The scientific method is a process by which scientists
gain confidence in theories by failing to prove them wrong.
A _________ becomes a _________ when repeated testing of its predictions does not disprove it.
hypothesis; theory
The most massive elements such as those that make up terrestrial planets like Earth were formed
inside stars and supernovae.
Which is an important element in the composition of your body that was produced by nuclear fusion inside a star or an explosion of a star?
iron calcium oxygen carbon
The majority of the energy in our universe is
made up of dark energy that permeates space.
The language of science is
mathematics
The diameter of the Moon is
more than half the distance across the continental US
A scientific theory can be shown to be wrong if
scientists gather new data that contradict its predictions.
The statement "our universe is but one of a multitude of isolated universes" is best characterized as a
speculative but unscientific idea because it is not testable and therefore not falsifiable.
The Local Group is the environment around
the Milky Way that contains a few thousand galaxies.
Because of _____________, we can conclude that gravity works the same way on Earth as it does on Mars.
the cosmological principle
The cosmological principle states that
the universe looks the same everywhere and in all directions as long as you look on large enough spatial scales.
A theory is
tied to known physical laws. able to make testable predictions. a hypothesis that has withstood many attempts to falsify it.
Scientific notation is used in astronomy primarily because it allows us to
write very large and very small numbers in a convenient way.