Planet that is one astronomical unit from the sun is

Earth

Explanation:

The astronomical unit (AU) was created to represent the average distance between the sun and the earth, and is used to measure distances in space to small to use lightyears, but too large to use kilometers.

doctrine that the us had the right to expand throughout north america.

true. earthquakes are felt whenever there is a slip around a fault in the rocks below the earth. this reorientation of faults create sesmic waves and is known as earthquake, the severity of which is measured in richter scale. these are more prominent in hilly regions as the rocks usually form faults to balance the pressures on it.