# Worksheet: Light-Years

In this worksheet, we will practice describing the distances between different objects that make up the Milky Way and the Universe.

Q1:

The speed of light is approximately m/s. There are approximately seconds in 1 year. Use these values to work out how far a beam of light will travel in 1 year. Give your answer to 2 significant figures.

• A m
• B m
• C m
• D m
• E m

Q2:

There are meters in 1 light-year. What is m in light-years? Give your answer to the nearest light-year.

Q3:

There are meters in 1 light-year. How many meters are there in 4 light-years? Give your answer to 2 significant figures.

• A m
• B m
• C m
• D m
• E m

Q4:

The Milky Way is about 100,000 light-years in diameter. 1 light-year is equal to . What is the diameter of the Milky Way in meters?

• A
• B
• C
• D
• E

Q5:

A laser beam was fired off into space from an observatory on Earth’s surface. The beam was fired into an empty region of space, so it would not interact with anything. How far, in light-years, has the beam traveled 3 years later?

Q6:

The speed of light is approximately . How far does a beam of light travel in 1 day? Give your answer to 2 significant figures.

• A
• B
• C
• D
• E

Q7:

Which of the following is the correct definition of a light-year?

• AA light-year is the distance traveled by a beam of light in 1 second.
• BA light-year is how far light travels in half a year.
• CA light-year is how long it takes a beam of light to travel the same distance that Earth travels in 1 year.
• DA light-year is the distance traveled by a beam of light in 1 year.
• EA light-year is how long it takes a beam of light to travel the distance from Earth to the Sun.

Q8:

List these objects in order of decreasing size:

• Saturn
• Pluto
• A weather satellite
• The Milky Way
• The universe
• AA weather satellite, Pluto, Saturn, the Milky Way, the universe
• BThe universe, the Milky Way, Pluto, Saturn, a weather satellite
• CA weather satellite, Saturn, Pluto, the Milky Way, the universe
• DThe universe, the Milky Way, Saturn, Pluto, a weather satellite

Q9:

What is the name of the galaxy that the Earth is a part of?

• AThe Small Magellanic Cloud
• BAndromeda
• CThe Large Magellanic Cloud
• DThe Milky Way
• ETriangulum

Q10:

List these objects in order of increasing size:

• The Moon
• The Sun
• The Andromeda Galaxy
• The International Space Station
• Earth
• AThe International Space Station, the Moon, Earth, the Sun, the Andromeda Galaxy
• BThe Moon, the International Space Station, Earth, the Sun, the Andromeda Galaxy
• CThe International Space Station, Earth, the Moon, the Sun, the Andromeda Galaxy
• DThe Andromeda Galaxy, the International Space Station, Earth, the Moon, the Sun

Q11:

Which of the following correctly describes a galaxy?

• AA galaxy is a collection of billions of stars.
• BA galaxy is a system of planets orbiting a star.
• CA galaxy is a cloud of gas and dust that condenses to form a protostar.
• DA galaxy is the remnant of a supernova.
• EA galaxy is a cluster of a few hundred stars.