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
별의 적경을 측정하는 것은 천문학에서 중요하다.byeol-ui jeokgyeong-eul cheugjeonghaneun geos-eun cheonmunhak-eseo jungyohada.Measuring the right ascension of a star is important in astronomy.