Question

The AU is defined as the average distance between Earth and the Sun, not the distance
between Earth and the Sun. Why does this need to be the case?
O Measurements between the Earth and the Sun aren't accurate due to atmospheric distortion
O Measurements between the Earth and the Sun are different depending on if we use ground based or
space based telescopes to do the measuring
Oc) The Earth/Sun distance isn't a constant

Answer 1

The correct answer is: The Earth/Sun distance isn't a constant. The average distance between the Earth and the Sun is known as the Astronomical Unit (AU). This is used as a standard unit of measurement in astronomy because the actual distance between the Earth and the Sun varies due to the elliptical shape of Earth's orbit around the Sun. Here's why the Earth/Sun distance isn't constant: 1. The Earth's orbit around the Sun is not a perfect circle; it's an ellipse. This means that the distance between the Earth and the Sun changes as the Earth moves along its orbit. 2. The Earth is closest to the Sun (perihelion) in early January and farthest from the Sun (aphelion) in early July. This variation in distance affects the accuracy of using the actual Earth/Sun distance as a standard unit of measurement. Therefore, the Astronomical Unit provides a more stable and standardized value for measuring distances within our solar system, as it represents the average distance between the Earth and the Sun, rather than the constantly changing actual distance.