Worksheet: Units of Astronomy: The Astronomical Unit (AU)

In this worksheet, we will practice converting between the astronomical length unit and meters and between the astronomical length unit and light-years.

Q1:

What is 3.1×10 km in AU? Give your answer to 2 significant figures.

Q2:

How many meters are there in 3.0 AU? Give your answer to 2 significant figures.

  • A4.3×10 m
  • B4.2×10 m
  • C4.5×10 m
  • D4.7×10 m
  • E4.1×10 m

Q3:

Saturn orbits the Sun at a distance of about 9.6 AU. What is this distance in meters? Give your answer to 2 significant figures.

  • A1.0×10 m
  • B1.4×10 m
  • C1.6×10 m
  • D1.2×10 m
  • E1.3×10 m

Q4:

What is 10.9×10 m in AU? Give your answer to 2 significant figures.

Q5:

Mercury orbits the Sun at a distance of about 5.79×10 m. What is this distance in AU? Give your answer to 2 significant figures.

Q6:

Pluto orbits the Sun at a distance of about 39 AU. How many hours does it take a beam of light from the Sun to travel this distance? Give your answer to 2 significant figures.

Q7:

How many kilometers are there in 210 AU? Give your answer to 2 significant figures.

  • A3.0×10 km
  • B3.0×10 km
  • C3.5×10 km
  • D3.2×10 km
  • E3.2×10 km

Q8:

Which distance is larger: 200,000 AU or 17 ly?

Q9:

Which of the following is the correct description of how the astronomical unit is defined?

  • AThe astronomical unit is a unit of length roughly equal to the distance between Earth and the Sun.
  • BThe astronomical unit is a unit of length roughly equal to the distance between Jupiter and the Sun.
  • CThe astronomical unit is a unit of length roughly equal to the distance between Venus and the Sun.
  • DThe astronomical unit is a unit of length roughly equal to the distance between Earth and the Moon.
  • EThe astronomical unit is a unit of length roughly equal to the distance between Pluto and the Sun.

Q10:

Proxima Centauri is the closest star to our solar system at a distance of 4.2 light-years. How far is this distance in AU? Give your answer to 2 significant figures.

Q11:

Which distance is larger: 1 astronomical unit or 1 light-year?

Q12:

What is 1 light-year in AU? Give your answer to 2 significant figures.

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