Rotation of Venus: Period Estimated from Radar Measurements

Science  08 Mar 1963:
Vol. 139, Issue 3558, pp. 910-911
DOI: 10.1126/science.139.3558.910


Venus may rotate in a direction opposite to that of the earth at a rate of only one revolution in 240 days. The estimated period is accurate within 20 percent if the axis of rotation of Venus is perpendicular to the plane of the planet's orbit.