 Gimbals, known as the "Beta Gimbal Assembly" (BGA) are used to rotate the arrays so that they face the Sun to provide maximum power to the International Space Station.The Alpha joint is the main rotary joint allowing the solar arrays to track the sun; in nominal operation the alpha joint rotates by 360° each orbit (however, see also Night Glider mode).One Solar Alpha Rotary Joint (SARJ) is located between the P3 and P4 truss segments and the other is located between the S3 and S4 truss segments.