What is an astronomical unit (AU)?
Q: What is an astronomical unit (AU)?
A: An astronomical unit (AU) is a unit of length derived from the Earth's orbit. It is the average distance the Earth gets from the Sun on the long axis of the ellipse.
Q: How is the AU defined?
A: The AU is defined as the length of the semi-major axis of the Earth's elliptical orbit around the Sun. "Semi-major" means half the long axis.
Q: What is the distance in kilometers of an astronomical unit?
A: An astronomical unit is about 150 million kilometers.
Q: What is the distance in miles of an astronomical unit?
A: An astronomical unit is about 93 million miles.
Q: What unit of measurement do astronomers usually use for measuring distances within the Solar System?
A: Astronomers usually measure distances within the Solar System in astronomical units.
Q: What is the distance of Mars from the Sun in astronomical units?
A: Mars is about 1.4 AU from the Sun.
Q: How long does it take for light to travel one astronomical unit?
A: Light travels an AU in about 8.317 minutes.
