What is Earth's diameter size in Astronomical Units? What is the best unit for Earth? Also, what is Earth's size in light-year?
Earth's diameter = 12756 km = 8.5269 E-04 AU = 1.35 E-09 LY. Best unit for size of space bodies is km or mile. .
IAU (International Astronomical Union) AU = 149597870.7 km. 1 light year (LY) = 6.29 E+04 AU. For the precision in measurements of angles, all the significant digits (sd) in size might be exact. For larger units like LY, this might not be so.