单项选择题
A.has a declination equal to twice that of the Sun B.comprises two stars that appear close together C.is twice as bright as a single star D.suddenly becomes much brighter and then fades
A.the Sun B.the Moon C.Venus D.None of the above
A.the declination is the opposite name to the latitude B.the algebraic sum of the colatitude and declination exceeds 90 C.the observer is in high latitudes above either polar circle D.the body is circumpolar