Perigee (Gr. 7repi, near, y the earth), in astronomy that point of the moon's orbit or of the sun's apparent orbit at which the moon or sun approach nearest to the earth. The sun's perigee and the earth's perihelion are so related that they differ 180° in longitude, the first being on the line from the earth toward the sun, and the second from the sun toward the earth. The longitude of the solar perigee is now 101°, that of the earth's perihelion 281°.