Astronomy chapter 1
If you wanted to show the distance between Earth and the Moon on the same scale, about how far apart would you need to place the two photos above?
1 meter (about the length of your arm)
Based on observations of the universal expansion, the age of the universe is about _________.
14 billion years
Each box in this figure represents a different level of structure in our universe. Each box is labeled with one of the numbers 1-5. Which box represents the Milky Way Galaxy?
3
Suppose you wanted to show the Sun on the same scale. About how big would it need to be?
3.5 meters in diameter (about 1112 feet across)
About how far away from Earth would the Sun be located on this scale?
375 meters (about the length of four football fields)
On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun?
About the distance across the United States
Which of the following is not a general difference between a planet and a star?
All planets are made of rock and all stars are made of gas.
What do we mean when we say that the universe is "expanding"?
Average distances between galaxies are increasing with time.
Why do the patterns of the stars in our sky look the same from year to year?
Because the stars in the constellations are so far away.
Which of the following are real motions of our "spaceship Earth"? Earth orbits the Sun. Earth and our solar system moves with the Milky Way galaxy relative to other galaxies in our Local Group. Earth moves with the Sun on an orbit around the center of the Milky Way galaxy. Earth and the Local Group move along with the Local Supercluster on an orbit around the center of the Universe.
Earth moves with the Sun on an orbit around the center of the Milky Way galaxy.
How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?
Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.
How are galaxies important to our existence?
Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.
What does this photograph show?
It is a picture of the Andromeda galaxy, located about 2.5 million light-years away.
Relative to the age of the universe, how old is our solar system?
It is about one-third the age of the universe.
What is the significance of this photograph?
It shows a person standing on the most distant world ever visited by a human being.
Regarding the history of the universe, which of the following is true? -All the chemical elements were created during the Big Bang, but some have been modified since that time as a result of radioactive decay. -All the current stars in our galaxy formed about the same time billions of years ago. -The Earth formed quickly after the Big Bang. -Key elements of which Earth and life are made, including carbon, oxygen, and iron, did not exist when the universe was born and were created later in stars.
Key elements of which Earth and life are made, including carbon, oxygen, and iron, did not exist when the universe was born and were created later in stars.
Using the ideas discussed in your text, in what sense are we "star stuff"?
Nearly every atom from which we are made was once inside of a star.
Could we see a galaxy that is 20 billion light-years away? (Assume that we mean a "lookback time" of 20 billion years.)
No, because it would be beyond the bounds of our observable universe.
Could you use the same scale to represent the distances to nearby stars? Why or why not?
No, the nearest stars would not fit on Earth with this scale.
These photos show two different astronomical objects. Which object is bigger, and by about how much?
Object 2 is more than a trillion times as large as Object 1.
How long does it take the Earth to complete one orbit around the Sun?
One year
Notice that Earth's axis is shown with an arrowhead in this diagram. What does the arrow point to?
Polaris, the North Star
These diagrams show a raisin cake before it is put in the oven and again one hour later after it has expanded during baking. Suppose you lived in Raisin 3 (the raisin labeled "3"). What would you have noticed about Raisin 2 during baking?
Raisin 2 is moving away from you at a speed of 2 cm/hr.
Where is our solar system located within the Milky Way Galaxy?
Roughly halfway between the center and the edge of the visible disk of the galaxy
If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy?
Several thousand years
Suppose we made a scale model of our Milky Way Galaxy in which the disk of the galaxy is the size of a football field. Which (if any) diagram represents the Sun on the same scale?
The Sun on this scale would be microscopic and too small to see on the screen.
This painting represents the Sun and planets (and two dwarf planets) of our solar system. What is not to scale in this painting?
The distances between the planets are not shown to scale.
This diagram represents Earth's rotation and orbit. What do we call the flat blue plane shown in this diagram?
The ecliptic plane
What do astronomers mean by the "Big Bang"?
The event that marked the beginning of the expansion of the universe
Which statement about motion in the universe is not true?
The mysterious "dark matter" is the fastest-moving material in the universe.
What is the ecliptic plane?
The plane of Earth's orbit around the Sun
Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?
The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart.
Which of the following best describes what we mean by the universe?
The sum total of all matter and energy
Which of the following has your "cosmic address" in the correct order?
You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe
The number of stars in the Milky Way Galaxy is approximately _________.
a few hundred billion
When we look at an object that is 1,000 light-years away we see it _________.
as it was 1,000 years ago
Astronomers infer that the universe is expanding because distant galaxies all appear to _________.
be moving away from us, with more distant ones moving faster
A typical galaxy is a _________.
collection of millions or billions of stars, bound together by gravity and orbiting a common center
Nearly all of the objects that you can see in this photograph are _____________.
galaxies
Rank the following objects from largest to smallest. sun, earth, galaxy, solar system
galaxy, solar system, sun, earth
A television advertisement claiming that a product is light-years ahead of its time does not make sense because _________.
it uses "light-years" to talk about time, but a light-year is a unit of distance
On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is _________.
small enough to fit within your hand
The term observable universe refers to _________.
that portion of the universe that we can see in principle, given the current age of the universe
Our solar system consists of _________.
the Sun and all the objects that orbit it
An astronomical unit (AU) is _________.
the average distance between Earth and the Sun
The total number of stars in the observable universe is about _________.
the same as the number of grains of sand on all the beaches on Earth
Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case _________.
we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2
If we imagine the history of the universe compressed into one year, with the present as the stroke of midnight at the very end of that year, dinosaurs became extinct _________.
yesterday morning
