Probably the most prominent and famous of all the star patterns now hangs high in the north as darkness falls – the prominent group of seven stars within the asterism Ursa Major (Big Bear) that we here in America refer to as The Big Dipper, although in the United Kingdom, they are better known as “The Plough.”
A widespread tradition also held that this star formation represented a wain, or farm wagon; the British knew it either as Arthur’s Wain (for King Arthur) or Charles’ Wain (for Charlemagne).
Other peoples have seen this stellar landmark as still other things. In the 7th century B.C., for example, the poet Homer described it as a bear. Interestingly, many Native American tribes also knew these stars as a bear. Is this sheer coincidence, or did their ancestors bring the name with them when they crossed from Asia to North America some 12 millennia ago?
May is the best month to see the Big Dipper as it is visible practically the world over. However, for those living south of the Tropic of Capricorn (23½° south latitude) it will be difficult to view, if at all.
When I journeyed to Easter Island in 1986 to view Halley’s Comet, I found the Big Dipper a most arresting sight, literally skimming just above the northern horizon. There it appeared upside down and seemingly enlarged thanks to the “Moon-illusion” effect. Only below 40 degrees south latitude – the bottom of South America, the South Island of New Zealand, and Tasmania – are none of the Dipper’s stars ever visible.
Joe Rao is an astronomer and contributes regularly to the Farmers' Almanac.