单项选择题
A.the Sun B.stars C.planets D.All of the above
A parallax correction is NOT applied to observations of...
单项选择题A parallax correction is NOT applied to observations of the（）.
A.stars B.Moon C.Sun D.Planets
A marine sextant has the index arm set at zero and the ...
单项选择题A marine sextant has the index arm set at zero and the reflected image of the horizon forms a continuous line with the actual image. When the sextant is rotated about the line of sight the images separate. The sextant has（）.
A.error of perpendicularity B.side error C.prismatic error D.centering error
A large group of stars revolving around a center is kno...
单项选择题A large group of stars revolving around a center is known as a（）.
A.cluster B.shower C.constellation D.galaxy
