Light-Year:
* Definition: The distance light travels in one year.
* Distance: Approximately 9.461 trillion kilometers (5.878 trillion miles).
* Usage: Used to measure distances to stars and other objects outside our solar system.
Astronomical Unit (AU):
* Definition: The average distance between the Earth and the Sun.
* Distance: Approximately 149.6 million kilometers (93 million miles).
* Usage: Used to measure distances within our solar system, such as the distances between planets.
Parsec:
* Definition: The distance at which one astronomical unit subtends an angle of one arcsecond.
* Distance: Approximately 3.26 light-years.
* Usage: Used to measure distances to nearby stars and other objects within our galaxy.
Here's a helpful way to remember the relationships:
* AU: "Average distance from the Sun" (useful within our solar system).
* Light-Year: "Distance light travels in a year" (useful for interstellar distances).
* Parsec: "Parallax Second" (related to measuring distances using parallax, a technique used for nearby stars).
