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Skywatch: A good time of year to get acquainted with the Big Dipper

Skywatch: A good time of year to get acquainted with the Big Dipper

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Have you ever seen the most famous of all star patterns? I’m talking about the Big Dipper. Now is the time of year when it is highest and most prominent in the evening hours, easiest to use as a guide to identifying the North Star.

In addition to discussing the Big Dipper, we’ll also cover the moon’s especially fascinating path by planets and bright stars these next two weeks.

The Big Dipper at its evening highest. The Big Dipper is not an official constellation. It is instead a glorious part of the even bigger, and official, star pattern called Ursa Major the Great Bear. The bowl of the Big Dipper is the bear’s hindquarters and the handle of the Big Dipper is the bear’s tail, a ridiculously long tail for a bear.

Stories about these stars being a bear have been told around the world and may date back as far as 10,000 years or more. But the term “Big Dipper” for the brightest part of the Great Bear dates back less than 200 years.

It is believed to have been invented by African Americans trying to flee north to escape slavery, creating a song about “following the drinking gourd.”

Why is the Big Dipper a way to find due north? Because a line drawn through the two “Pointers” stars of the Big Dipper point almost directly to Polaris, the North Star, which itself exactly marks due north. Which are the “Pointers?” They are the two stars on the opposite side of the Big Dipper’s bowl from the handle.

You always draw the line through the Pointers from the imagined bottom to top of that side of the bowl. The only trick is that at some times of year and night the Big Dipper appears upside down.

That is true in April around 9 p.m., so the Big Dipper is now far above the North Star and you have to draw a line down through the Pointers. There is another fascinating star you can use the Big Dipper to find. If you extend the arc of the Big Dipper’s handle out about one Big Dipper length, it takes you to the brightest star of spring, Arcturus.

A key star in the Big Dipper itself is the star Mizar at the bend in the dipper’s handle. If you look carefully with good eyesight, you should see the much dimmer star Alcor right next to Mizar.

The moon’s journey past three bright planets and three bright stars. If you are reading these words an hour before sunrise April 6, the bright point of light above the crescent moon in the southeast is the modestly bright planet Saturn.

Most of us won’t be reading the newspaper so early, but April 7 at dawn, there will be a much brighter planet fairly near the moon.

That planet, also straight above the quite slender moon, is Jupiter. The best time to look is roughly 6 a.m. April 7.

Next week, the moon switches to being visible after sunset, a convenient time. The first chance to see the moon at dusk is Monday, April 12. That will be a tricky observation, though, because the moon will be very slender and very low in bright evening twilight.

Even a mere 30 minutes after sunset, the sliver of lunar crescent is already virtually down on the horizon (a little north of due west). Binoculars may help a lot to see that night’s moon.

On Thursday, April 15, a thicker crescent moon shines much higher and just to the right of the bright star Aldebaran, the star that marks the eye of Taurus the Bull.

Then on April 16 and 17, the moon has its closest pairings with the fading but untwinkling and orange-gold Mars. Look for Mars upper left of the moon on April 16 and lower right of the moon April 17. Last but not least, on Monday, April 19, the moon, just short of half lit, forms a nearly perfect compact line with the two brightest stars of Gemini the Twins, Castor and Pollux.

Fred Schaaf is a local author and astronomer. He can be reached at fschaaf@aol.com.

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