What type of measurements do astronomers use within the solar system?

Astronomers commonly utilize Astronomical Units (AU) when measuring distances within our solar system, primarily because this unit provides a more manageable scale for the vast distances involved. One AU is defined as the average distance from the Earth to the Sun, approximately 93 million miles or about 150 million kilometers.

Using Astronomical Units allows astronomers to conveniently express distances between celestial bodies like planets, moons, and the Sun in a way that is more intuitively grasped. For instance, instead of dealing with large numbers in kilometers or miles, they can refer to the distance between Earth and Mars in AUs, generally making it easier to understand the scale of our solar system.

While kilometers and miles are indeed valid units of measurement, they are less practical for the astronomical scale since distances can become extraordinarily cumbersome to express. Light years represent the distance light travels in one year and are typically used for measuring distances between stars and galaxies beyond our solar system, making it unsuitable for comparing distances within the solar system.