2007-03-12 15:09:16 · 8 answers · asked by azizka93 3 in Science & Mathematics ➔ Astronomy & Space
The Astronomical Unit, or A.U. is defined to be the average orbital distance from the Earth to the sun, so the short answer is 1
However the Earth's orbit is elliptical, not circular, so the distance actually ranges from 0.983 AU at closest approach (Perihelion) and 1.017 AU at its furthest (Aphelion).
To ancient astronomers, the distance from the Earth to the sun was very difficult to measure precisely. Assuming that the sun was in the center of the solar system (A contentious assumption in the old days) and observing the motions of the other planets, it was possible to determine the orbital distances of the other planets in the solar system, relative to the distance of the Earth from the Sun, as a ratio. Thus the unit of measurement for astronomical distances, the AU was born!
2007-03-12 16:58:19 · answer #1 · answered by Graham S 3 · 0⤊ 0⤋
1
2007-03-13 05:47:45 · answer #2 · answered by Sonderval 2 · 0⤊ 0⤋
1
2007-03-12 22:25:21 · answer #3 · answered by aussie1_1950 2 · 0⤊ 1⤋
This is a trick question, right? Like asking someone which is the closest star to the earth and hoping to trip them up and they answer Alpha Centauri or something like that?
Since an AU is defined as the average distance from the earth to the sun, the distance from the earth to the sun is by definition 1 A.U.
2007-03-12 22:15:02 · answer #4 · answered by Anonymous · 0⤊ 1⤋
The average distance between the earth and sun is defined to be 1 astronomical unit.
2007-03-12 22:12:38 · answer #5 · answered by Ken M 3 · 0⤊ 1⤋
Earth to sun distance = 1 A.U.
1 A.U. = 149,600,000 km
2007-03-12 22:13:49 · answer #6 · answered by Chug-a-Lug 7 · 0⤊ 1⤋
One AU is the average distance from the Sun's center to the Earth's center.
2007-03-12 23:31:46 · answer #7 · answered by spaceprt 5 · 0⤊ 0⤋
1 astrnomical unit...this is where the idea of a. u. eminated
2007-03-12 23:24:35 · answer #8 · answered by Anonymous · 0⤊ 1⤋