1 2020, questions and answers PDF

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1.

Which of the following is NOT a general difference between a planet and a star? [Hint] All planets are made of rock and all stars are made of gas. Planets are smaller than stars. Planets are dimmer than stars. Planets orbit stars, while stars orbit the center of the galaxy.

2.

Our solar system consists of _________. [Hint] the Sun and several nearby stars, as well as the planets and other objects that orbit these stars the Sun and the nine planets, and nothing else the Sun and all the objects that orbit it a few hundred billion stars, bound together by gravity

3.

A typical galaxy is a _________. [Hint] large, glowing ball of gas powered by nuclear energy relatively small, icy object orbiting a star collection of a few hundred million to a trillion or more stars, bound together by gravity system consisting of one or a few stars orbited by planets, moons, and smaller objects nearby object orbiting a planet

4.

Which of the following best describes what we mean by the universe? [Hint] The universe is another name for our Milky Way Galaxy. The sum total of all matter and energy A vast collection of stars that number as many as the grains of sand on all the beaches on Earth

All the galaxies in all the superclusters

5.

What do astronomers mean by the Big Bang? [Hint] The event that marked the beginning of the expansion of the universe The explosion of a massive star at the end of its life The event that marked the birth of our solar system A gigantic explosion that blew all the galaxies in the universe to smithereens

6.

What do we mean when we say that the universe is expanding? [Hint] The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing. Average distances are increasing between star systems within galaxies. Average distances between galaxies are increasing. Everything in the universe is gradually growing in size.

7.

x Based on observations of the universal expansion, the age of the universe is about _________. [Hint] 14 billion years 14 million years 14,000 years 14 trillion years

8.

A television advertisement claiming that a product is light-years ahead of its time does not make sense because _________. [Hint] a light-year is an astronomically large unit, so a product could not possibly be so advanced it doesn't specify the number of light-years

it uses "light-years" to talk about time, but a light-year is a unit of distance light-years can only be used to talk about light

9.

The term observable universe refers to _________. [Hint] that portion of the universe that we can see in principle, given the finite age of the universe that portion of the universe that we have so far photographed through telescopes the portion of the universe that is not hidden from view by, for example, being below the horizon the portion of the universe that can be seen by the naked eye

10 .

On a scale in which the distance from the Sun to the Earth is about 15 meters, the distance from the Earth to the Moon is _________. [Hint] small enough to fit within your hand about 5 meters about 1 meter about 30 meters

11 .

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? [Hint] About the distance across the state of Delaware About the distance across 50 football fields About the distance across the United States 100 meters

12 .

The number of stars in the Milky Way Galaxy is approximately _________.

a few hundred a few hundred thousand a few hundred billion a few hundred million

13 .

An astronomical unit (AU) is _________. [Hint] the average distance between the Sun and Earth any very large unit, such as a light-year the average distance between any two planets the average distance between the Sun and Pluto

14 .

What is the ecliptic plane? [Hint] The plane of the Milky Way Galaxy The plane of the Earth's equator The plane of the Sun's equator The plane of the Earth's orbit around the Sun

15 .

How long does it take the Earth to complete one orbit around the Sun? One day One month The time varies significantly depending on the orbit. One week

One year

1.

Which of the following has your "cosmic address" in the correct order? [Hint] You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe You, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe

2.

Using the ideas discussed in the text, in what sense are we "star stuff"? [Hint] Our overall chemical composition is about the same as that of stars. We could not survive without light from our star, the Sun. Nearly every atom from which we are made was once inside of a star. Movie stars and other people are all made of the same stuff, so we all have the potential to be famous.

3.

How are galaxies important to our existence? [Hint] Without galaxies, the universe could not be expanding. Deep in their centers, galaxies created the elements from which we are made. Without galaxies, there could not have been a Big Bang. Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.

4.

When we look at an object that is 1,000 light-years away we see it _________. [Hint] looking just the same as our ancestors would have seen it 1,000 years ago as it was 1,000 years ago as it is right now, but it appears 1,000 times dimmer as it was 1,000 light-years ago

5.

Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case _________. [Hint] we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2 Galaxy 2 must be twice as old as Galaxy 1 Galaxy 1 must be twice as big as Galaxy 2 we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2

6.

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? [Hint] They are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the remaining planets are spread much farther apart, with Pluto more than a half a kilometer from the Sun. The planets range in size from about the size of a marble to the size of a baseball. They are spread out over a region about the size of a football field.

They are all much smaller than the Sun and are spread out evenly over a distance about the length of a large classroom. They are all much smaller than the Sun. Six planets are located within a few centimeters of the Sun, and three planets are located at distances ranging up to about a meter. 7.

How long would it take to count all the stars in the Milky Way Galaxy at a rate of one star per second? [Hint] Several weeks Several thousand years Several days Several years

8.

The total number of stars in the observable universe is about _________. [Hint] the same as the number of grains of sand on all the beaches on Earth the same as the number of grains of sand in a large sandbox the same as the number of atoms that make up the Earth 100 billion

9.

Where is our solar system located within the Milky Way Galaxy? [Hint] Roughly halfway between the center and the edge of the visible disk of the galaxy (two-thirds of the way) Very near the center of the galaxy At the far edge of the galaxy's visible disk In the halo of the galaxy

10 .

If we imagine the history of the universe compressed into one year, the dinosaurs became extinct _________. [Hint] about 6 months ago

about an hour ago yesterday about 3 weeks ago

11 .

Relative to the age of the universe, how old is our solar system? [Hint] It is about the same age as the universe because it formed shortly after the Big Bang. It is between about one-quarter and one-half the age of the universe It is about 1% as old as the universe. It is between about 5% and 10% as old as the universe.

12 .

How do the speeds at which we are moving with the Earth's rotation and orbit compare to the speeds of more familiar objects? [Hint] The Earth's rotation is carrying most people around the axis at about the speed of a commercial jet, and the Earth's orbit is carrying us around the Sun at about the speed of a military jet. The Earth's rotation is carrying most people around the axis faster than a commercial jet travels, and the Earth's orbit is carrying us around the Sun faster than the Space Shuttle orbits the Earth. The Earth's rotation is carrying most people around the axis at about the speed of a car on the freeway, and the Earth's orbit is carrying us around the Sun at about the speed of a commercial jet. The Earth's rotation is carrying most people around the axis at about the speed at which the Space Shuttle orbits the Earth, and the Earth's orbit is carrying us around the Sun at nearly the speed of light.

13 .

Why do the patterns of the stars in our sky look the same from year to year? [Hint] Because although these stars are moving, they move so slowly --- typically about the speed of a snail --- that their motion is not noticeable. Although these stars move quite fast by human standards, they are so far away that it would take thousands of years for their motion to be noticeable to the eye. Because although these stars move quite fast as they orbit around the Milky Way Galaxy, they all move together so they don't change their relative positions. Because these stars are not moving.

14 .

Astronomers infer that the universe is expanding because distant galaxies all appear to _________. [Hint] rotate rapidly be moving away from us, with more distant ones moving faster be made of dark matter be growing in size

Which statement about motion in the universe is NOT true? [Hint] Except for a few nearby galaxies, all other galaxies are moving away from us.

15 .

The mysterious dark matter is the fastest-moving material in the universe. Some stars are moving closer to us and others are moving farther away from us. Your speed of rotation around Earth's axis is faster if you live near the equator than if you live near the North Pole.

1)

What is the meaning of the word “cosmos”?

Ans: The sum total of all matter and energy, that is, everything within and between all galaxies. 2) About where is our solar system located within the milky way galaxy? Ans: About two-thirds of the way from the center of the galaxy to the outskirts of the galactic disk. 3) Suppose we imagine the Sun to be about the size of a grapefruit. How big an area would the orbits of the eight planets of the solar system cover? Ans: The size of a typical campus 4) How are galaxies important to our existence?

Ans: Galaxies recycle heavy elements produced in stars into future generations of stars 5) Which of the following statements does not use the term light-year in an appropriate way? Ans: It will take me light-years to complete this homework assignment 6) One light-hour is the distance that light travels in an hour. How far is this, in kilometres? (Recall that speed of light is 300,000km/s) Ans: 1.08 billion km 7) Which of the following is the smallest? a) b) c) d)

Size of a typical planet 1 light-second 1 AU Size of a typical star

Ans: Size of a typical planet 8) Which of the following correctly lists speeds from slowest to fastest? Ans: Earth’s speed of rotation on its axis, Earth’s speed of revolution about the Sun, typical speeds of stars in the local solar neighbourhood relative to us, the speed of our solar system orbiting the centre of the Milky Way Galaxy, the speeds of very distant galaxies relative to us. 9) Which of the following statements about the celestial sphere is not true? a) b) c) d) e)

When we look in the sky, the stars all appear to be located on the celestial sphere. Earth is placed at the centre of the celestial sphere. The celestial sphere does not exist physically. The “celestial sphere” is just another name for our universe. From any location on Earth, we can see only half the celestial sphere at any one time.

Ans: D. 10) How many arcseconds are in 1? Ans: 3,600. 11) Orion is visible on winter evenings but not summer evenings because of Ans: The location of Earth in its orbit 12) Which of the following statements about constellations is false? a) b) c) d) e)

There are only 88 official constellations. Some constellations can be seen from both the Northern and Southern hemispheres Some constellations can be seen in both the winter and summer It is possible to see all the constellations from Earth’s equator Most constellations will be unrecognisable hundreds of years from now.

Ans: E. 13) Which of the following is NOT a phase of the Moon? a) b) c) d) e)

First-quarter Moon Third-quarter Moon Half moon New moon Full moon

Ans: C. Half moon 14) If the moon is setting at 6am, the phase of the moon must be Ans: Full. 15) Why do we see essentially the same face of the Moon at all times? Ans: Because the Moon’s rotational and orbital periods are equal. 16) What conditions are required for a lunar eclipse? Ans: The phase of the Moon must be full, and the nodes of the Moon’s orbit must be nearly aligned with Earth and the Sun.

17) How fast is the Moon orbiting the Earth? Ans: 3700km/hr 18) The speed of light is 300,000km/s. How far is a light-year? Ans: 9,460,000,000,000 km

TRUE/FALSE Questions 1) Our solar system is located in the center of the Milky Way Galaxy. FALSE 2) The solar system contains about 100 billion stars. FALSE

3) A typical supercluster contains no more than about 10,000 stars. FALSE

4) One light-year is about 10 trillion kilometres. TRUE

5) In the grapefruit model of the solar system, it would take a few minutes to walk from the Sun to the inner edge of the Kuiper Belt (Pluto). TRUE

6) In South Africa, it’s usually quite warm around the time of the winter solstice and quite cool around the time of the summer solstice. TRUE

7) Columbus was the first person to discover that Earth is round. FALSE

8) You can find the tilt of the Earth’s axis by measuring the angle between your horizon and the North Star. FALSE

9) The Milky Way can be seen only from the Northern Hemisphere. FALSE

10) The seasons on Earth are caused by its elliptical orbit around the Sun. FALSE

Consider the following statement, and explain whether or not it is sensible 1) NASA hopes to build a new telescope that will allow us to see 100 million light-years into the past.  Not sensible as it uses light-years as a length of time. 2) NASA hopes to build a new telescope that will allow us to see some galaxies as they appeared 8 billion years ago.  Sensible. By looking at the distance of 8 billion light-years, we can see objects as they looked 8 billion years ago. 3) The universe is between 10 and 16 billion light-years old.  Does not make sense as it uses the term “light-year” as a length of time, rather than as a distance....