* Light-year: The distance light travels in one year. This is a convenient unit because it reflects the vast distances involved in interstellar space. One light-year is about 5.88 trillion miles (9.46 trillion kilometers).
* Parsec: A parsec is defined as the distance at which one astronomical unit (the average distance between the Earth and the Sun) subtends an angle of one arcsecond. One parsec is roughly equal to 3.26 light-years. Parsec is often used by astronomers because it is directly related to the measurement technique called parallax.
* Astronomical Unit (AU): While primarily used for distances within our solar system, AU is also used for nearby stars. One AU is equal to the average distance between the Earth and the Sun (about 93 million miles or 150 million kilometers).
Let me know if you'd like a more detailed explanation of any of these units!
