Question

How far away is the sun from the earth in AU?

Answer 1

AU is the unit of measurement of distance. The distance between the objects in outer space is so large that the conventional systems of distance measurement become inconvenient, so the scientists formulated AU as astronomical units for distance calculation in space to reduce the complexity of calculations.

Complete solution:
Astronomical Unit: For general reference, we can say that one astronomical unit (AU) represents the mean distance between the Earth and our Sun. An AU is approximately 93 million miles (150 million km). It’s approximately the distance covered by light in 8 minutes or we can that it is approximately equal to 8 light-minutes.
Earth’s orbit around the sun isn’t a perfect circle. So, Earth’s distance from the sun changes throughout the year. Astronomers give the Earth’s changing distance throughout the year relative to the astronomical unit, too. For instance, when the Earth is at its nearest point to the sun for the year, in January – it’s about 0.983 AU from the sun. When our planet swings out to its farthest point, in July – we’re about 1.017 AU away from the sun.
So, we can say that the distance of the sun from the earth is not constant; it varies with time so take the average distance between the sun and earth as 1 AU.
Mathematically: 1 AU$= 1.496 \times {10^8}$km
Final Answer: The distance between sun and earth is 1 AU which is equal to 150 million km approx.

Note: The orbit of the earth around the sun is elliptical as an ellipse as a major and a minor axis so the distance between its periphery and the centre is not constant but it varies so the astronomers devised 1 AU as the average distance between the sun and earth which keeps on changing its value from 0.983 AU to 1.017 AU.