Astronomical Unit (Noun)
Meaning
A unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers).
Classification
Nouns denoting quantities and units of measure.
Examples
- The concept of the astronomical unit was first proposed by ancient Greek philosopher Aristarchus of Samos to describe the vast scales of interplanetary distances.
- The International Astronomical Union formally defined the astronomical unit as the mean distance between the Earth and the Sun in 1976.
- Due to the elliptical shape of Earth's orbit, its distance from the Sun varies, but the astronomical unit serves as a reliable average.
- Scientists often use the astronomical unit as a convenient scale when describing vast distances between celestial objects within the solar system.
- To facilitate more precise calculations, astronomers can express great distances in units of astronomical units rather than in miles or kilometers.