CREATE TABLE table_37865 ("orbit" TEXT, "center-to-center distance" TEXT, "altitude above the Earth's surface" TEXT, "Orbital period" TEXT, "specific orbital energy" TEXT)

altitude above the Earth's surface of 500 to 39,900 km has what orbital period?
SELECT "Orbital period" FROM table_37865 WHERE "altitude above the Earth's surface" = '500 to 39,900 km'
SELECT "Orbital period" FROM "table_37865" WHERE "altitude above the Earth's surface" = '500 to 39,900 km'