Q: If the speed of light is $$300,000$$ kilometers per second, how many kilometers does light travel in one year? (Use $$1$$ year $$= 3.15 \times 10^7$ seconds)

$$9.46 \times 10$$^{12}$$ kilometers

Question 1

Which of the following best describes a light-year?

Accepted Answer

The distance light travels in one year.

Question 2

If the speed of light is $$300,000$$ kilometers per second, how many kilometers does light travel in one year? (Use $$1$$ year $$= 3.15 	imes 10^7$ seconds)

Accepted Answer

$$9.46 	imes 10$$^{12}$$ kilometers

Question 3

Which statement about the observable universe is correct?

Accepted Answer

It is limited by the age of the universe and the speed of light.

Question 4

What is the correct order of cosmic structures from smallest to largest?

Accepted Answer

Planet, solar system, galaxy, supercluster, universe

Question 5

If the Andromeda Galaxy is $$2.5$$ million light-years away, what does this mean about the light we see from it?

Accepted Answer

We see the Andromeda Galaxy as it was $$2.5$$ million years ago.

Question 6

Which of the following is NOT a criterion for an object to be considered a planet according to the modern definition?

Accepted Answer

It must have at least one moon.

Question 7

A spacecraft travels at $$30,000 km/hr. If $$Alpha Centauri is $$4.4$$ light-years away, approximately how long would it take the spacecraft to reach Alpha Centauri? (Use $$1$$ light-year $$= 9.46 	imes 10$$^{12}$$ km)

Accepted Answer

$$1.4 	imes 10^5$ years

Question 8

Which of the following best explains why Pluto is classified as a 'dwarf planet'?

Accepted Answer

It has not cleared its orbital path of other objects.

Question 9

If you count one star per second, how long would it take to count all $$100$$ billion stars in the Milky Way Galaxy?

Accepted Answer

$$3,170$$ years

Question 10

Which of the following is a correct statement about the relationship between galaxies and superclusters?

Accepted Answer

Superclusters are regions where galaxy clusters are packed more tightly together.

Question 11

On a scale where the Sun is the size of a grapefruit, how far would Earth be from the Sun?

Accepted Answer

About $$15$$ meters

Question 12

Why do astronomers use light-years instead of kilometers to describe distances between stars and galaxies?

Accepted Answer

Because distances in space are so large that kilometers are not convenient.

Question 13

Which of the following is true about the Milky Way Galaxy?

Accepted Answer

It contains more than $$100$$ billion stars.

Question 14

If a galaxy is $$12$$ billion light-years away, what does this tell us about the age of the universe when the light left that galaxy?

Accepted Answer

The universe was about $$2$$ billion years old.

Question 15

Which of the following is a correct definition of 'rotation' in astronomy?

Accepted Answer

The spinning of an object around its axis.

Question 16

What is the average distance between Earth and the Sun, known as an astronomical unit (AU)?

Accepted Answer

$$150$$ million kilometers

Question 17

If the observable universe contains about $$100$$ billion galaxies, each with about $$100$$ billion stars, approximately how many stars are in the observable universe?

Accepted Answer

$$10^{22}$$ stars

Question 18

Which of the following objects is classified as a 'small solar system body'?

Accepted Answer

Asteroid

Question 19

Why is it impossible to observe light from beyond $$14$$ billion light-years away?

Accepted Answer

Because the universe did not exist before then.

Question 20

Which of the following best describes the concept of 'lookback time' in astronomy?

Accepted Answer

The time it takes for light from a distant object to reach us, so we see the object as it was in the past.

The Scale of the Universe: Our Cosmic Address and Astronomical Structures

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