The Pleiades star cluster in Taurus contains hundreds of stars, although most observers can distinguish only a handful with the naked eye. (Image credit: Taurus via Getty Images)

Every autumn, I conduct an eyesight test that no reputable optometrist would understand.

I go outside, find the Pleiades and count how many stars I can see. Usually I start confidently. One, two, three, four, five. Then things become contentious. Is that another star? Did I actually see it, or did I decide I ought to see it because I know it's there? I look away, look back and begin again.

This is not, I should emphasize, a meaningful test of eye health. What it tests, rather, is how badly I've prepared for looking at the night sky.

The Pleiades sit roughly 444 light-years away in Taurus and are right now becoming extremely convenient in the evening sky. You don't need a telescope to find them. You don't even need binoculars.…