CREATE TABLE table_name_75 (eccentricity VARCHAR2, semimajor_axis___au__ VARCHAR2)

What is the eccentricity when the semimajor axis is 20 au?
SELECT eccentricity FROM table_name_75 WHERE semimajor_axis___au__ = "20 au"
SELECT "eccentricity" FROM "table_name_75" WHERE "20 au" = "semimajor_axis___au__"