Final answer:
Astronomers use Astronomical units (AU) when discussing distances between objects in the solar system. Light-years are used to measure large distances in the universe. Parsecs are used to measure distances to stars and other objects outside of our solar system.
Step-by-step explanation:
When discussing distances between objects in the solar system, astronomers use the term Astronomical units (AU). An Astronomical Unit is the average distance between the Earth and the Sun, which is about 149.6 million kilometers or 93 million miles. It is a convenient unit to measure distances within the solar system.
Light-years are used to measure large distances in the universe. A light-year is the distance that light travels in one year. It is equal to about 9.5 trillion kilometers or 6 trillion miles.
Parsecs are also used in astronomy. A parsec is a unit of distance that is equal to about 3.26 light-years or 31 trillion kilometers. It is used to measure distances to stars and other objects outside of our solar system.