Not bad. Not all binaries are visual binaries, though.

不错的。不过并不是所有的双星都是目视双星。

These kinds of stars are fairly common: the brightest star in the night sky, Sirius, is a visual binary.

夜空中最亮的恒星，天狼星，就是一颗目视双星。

Visual binaries are important, because, if you observe them long enough you might be able to see their orbital motion.

目视双星很重要，因为，如果你观察它们的时间足够长，你也许能看到它们的轨道运动。

In even a small telescope you can see that Mizar is actually a visual binary… but it turns out that both of those two stars making up Mizar are actually SPECTROSCOPIC binaries, too.

即使是用一个小望远镜，你也可以看到开阳星实际上是目视双星… … 但事实证明，组成开阳星的这两颗恒星其实也是分光双星。