May 28, 2024

Starwatch chart

The seven brightest stars in Ursa Major, the Great Bear, form the shape known as the Plough, or the Great Bear, or by a number of other names in different cultures.

The association with a bear dates back to antiquity, when it was listed in Ptolemy’s original 48 constellations from the second century AD. Now included in the International Astronomical Union’s list of 88 modern constellations, it occupies a little over 3% of the entire night sky, making it the third largest constellation by area.

The star Mizar, in the handle of the Plow, or the tail of the bear, is actually a double star and on quiet nights, from places without light pollution, its fainter companion, called Alcor, is visible to the naked eye.

The constellation can also be used to fix Polaris, the pole star. Starting at Merek and extending a line through Dubhe leads to the pole star.

Because Ursa Major is so high in the northern sky, it is difficult to see from much of the southern hemisphere. From Cape Town, South Africa, for example, only its legs are visible, protruding from the northern horizon at this time of year.

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