One AU is the distance between Earth and the Sun. No planet is that big across so you can only be talking about distance from the sun and in that case Earth by definition has an astronomical unit.
The International Astronomical Union (IAU). This is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy.
An Astronomical Unit (AU) is equal to the following common distance terms.
149,600,000 kilometres
92,960,000 miles
163,600,000,000 yards
490,800,000,000 feet
5,890,000,000,000 inches
0.00001581...