On the next clear evening, go outside as soon as it gets dark and find the Big Dipper. Take a good long look at the star at the bend in its Handle. Do you see anything odd about it? Now take a peek with binoculars or any telescope, and its secret will be revealed: this is actually two stars, named Mizar (the brighter one) and Alcor. If your vision is sharp, you should be able to just make out Alcor with your eyes alone.
But wait there’s more! Using even a small telescope at low power, you’ll see a faint third star forming a triangle with Mizar and Alcor. Now focus on Mizar itself, and switch to a higher-power eyepiece. It’s a double too, a pair of pinpoints nearly touching each other.
Congratulations! You’ve just tracked down the first double star system ever discovered and you’ve learned that not every star is a loner.
Not surprisingly, astronomers based their early assumptions about other stars largely on what they knew about our own Sun. And since the Sun is solitary, they thought all other suns were individuals as well. But it turns out that at least half of all stars and perhaps as many as 80% of them are members of double and multiple systems. Many hundreds of these are observable with small backyard telescopes.