Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
천문학자들은 실로스태트를 사용하여 태양의 위치를 추적합니다.cheonmunhakjadeul-eun silloseutaeteul sayonghayeo taeyang-ui wichi-reul chujaghamnida.Astronomers use a coelostat to track the position of the sun.