Few skywatchers can boast of spotting Mercury on more than isolated occasions. How can a planet that becomes as bright as the brightest stars be so elusive?
Of all the planets that are visible to the naked eye, Mercury is the least often observed.
The reason lies in its orbit.
Because Mercury is the closest planet to the Sun, its year lasts just 88 days, and it never strays more than 28 degrees from the blaze of light surrounding the Sun. Observers usually glimpse it just before sunrise or soon after sunset, and they can never see it in a fully dark sky.
For all this, antiquity's astronomers knew of Mercury and carefully logged its appearances. In Mesopotamia, where clear desert twilights and low horizons made it easier to see, this come-and-go object was named Nabu; he was a scribe and a messenger of the gods. The planet's swift apparitions also prompted the Greeks to name it after a heavenly messenger—Hermes. The Romans translated the name into Latin as Mercurius.