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Big Dipper points to Polaris, helps find Thuban


Tonight for July 8, 2015

You can use the Big Dipper in the constellation Ursa Major the Great Bear to find the sky’s pole star, Polaris. Draw a line through the Big Dipper’s pointer stars – Dubhe and Merak – to locate Polaris the North Star. Once you’ve got Polaris, if your sky is dark enough, you might be able to see the Little Dipper asterism. It’s harder to spot than the Big Dipper and needs a dark sky to be seen. And once you have all those, look for Thuban, a famous star in the constellation Draco the Dragon.

Our chart shows the Big Dipper and Polaris as you’ll see them in the north on July evenings. But you can use the pointer stars in the Big Dipper to find Polaris any evening – no matter how the Dipper is oriented with respect to the horizon.

Polaris isn’t the brightest star in the sky, as is commonly supposed. It’s only the 50th brightest or so. Still, Polaris is bright enough to be seen with relative ease on a dark, clear night. This star is famous not for its brightness but for its location in our sky. It’s located above the Earth’s northern axis. Thus the entire northern sky appears to turn around Polaris.

Polaris is noteworthy for another reason. It marks the end of the handle on the Little Dipper asterism, in the constellation Ursa Minor. The asterism is not the whole constellation, but a noticeable pattern within the constellation Ursa Minor the Smaller Bear.

More about Polaris: the North Star

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As night deepens, and the fainter stars of the Little Dipper spring into view, those of you with dark-enough skies can expect to see a winding stream of stars between the Big and Little Dippers. What is this stream of stars between the Dippers? The star Thuban is one of the stars here, part of the Tail of the legendary constellation Draco the Dragon, a fixture of the northern skies.

Click here to read more about Draco, the great Dragon of the north

July 2014 guide to the five visible planets

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