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Mountain Skies: The Big Dipper Dominates The Far North Sky

 

Last updated 5/18/2020 at 12:33pm

The Stars

This is a good time of the year to observe the Big Dipper, also known as the Drinking Gourd. Early in the evening, we can find it high in the North lying with the dipper open downward. By 3 a.m. it will have swung over to the northwest. Since the Little Dipper is below the Big Dipper in the early evening, it appears that the Big Dipper is "pouring" its contents into its smaller namesake. Except for two stars, one each at the end of the handle and the tip of the bowl, the remaining five stars in the Big Dipper are all at approximately the same distance from us, about 80 light years. This is unusual since, typically, constellations consist of stars that lie at vastly different distances.

The Big Dipper is important because it is an easily recognized pattern that we can use to find other stars in the sky. There are several common "tricks" involving the dipper. The most important is finding the North Star, Polaris. Locate the two stars that mark the end of the bowl of the dipper. Then draw a line between them and extend it five times their separation in the direction of the open end of the dipper. Following this line, you will come to the North Star, also known as Polaris.

The Big Dipper is not one of the 88 official constellations. Instead, its invention is particularly American. In other countries and traditions around the world, this obvious pattern is known as the plough (England), Charles' wain or wagon (Scotland) or a bear (many Native American cultures). Officially, it is the hindquarters and the long, bushy tail of Ursa Major, the Great Bear. Astronomers would call the Big Dipper an asterism, not a constellation.

The Planets

An observer with a moderate sized telescope might see all eight of the planets these nights:

Mercury and Venus in the evening twilight; Mars, Saturn and Jupiter well up in the southeast at dawn; Neptune in the morning twilight and, late this month, Uranus before sunrise. Of course, don't forget the earth under the observer's shoes.

The elusive Mercury has now moved high enough to be spotted in the evening twilight. It will stand higher each evening until early June.

Venus is diving into the evening twilight but still bright. It passes the sun on June 3 so it will be "lost" late in this month. Diving Venus will pass rising Mercury on May 22 and the two will be joined by a thin waxing crescent moon the next evening.

Mars rises about 3 a.m. and stands well up in the southeast at dawn. It lies in the eastern reaches of Capricornus, the sea-goat (or goatfish).

Both Jupiter and Saturn rise about 1 a.m. between Capricornus and Sagittarius. Both begin their retrograde motions this month.

Neptune rises out of the morning twilight. One needs a telescope of moderate size to spot it.

Uranus is just coming out of the morning twilight. The experienced observer with a telescope may spot it the last week of the month.

Comets

For the amateur astronomer, the skies of late have been offering views of four comets, a couple of which have shown tantalizing hints that they might become bright enough to be seen with the naked eye. As of this writing that has not yet materialized, but sky gazers continue to follow these fascinating objects as they pass through the inner part of the solar system. Early on, hopes were set for ATLAS (C/2019 Y4) to brighten that much; however, later observations showed it had broken into as many as four pieces and, thus, was much fainter than anticipated. In the region of Camelopardalis (the giraffe), we can find comets ATLAS (2019 Y1) and PanSTARRS (C/2017 T2). The latter will be crossing the bowl of the Big Dipper in June. All three of these comets are far enough North in the sky that they are circumpolar from the Carolina mountains. What this means is that, as Earth turns, they appear to circle the North Star and never set. On the opposite side of the sky we have Comet SWAN (C/2020 F8) heading northward. All four of these comets are currently bright enough for observing with amateur telescopes but, so far, not the naked eye. Keep your fingers crossed!

Celestial Calendar

May 22, 3 a.m. EDT, Mercury 0.9° south of Venus.

May 22, 1:39 p.m. EDT, New moon.

May 29, 11:30 p.m. EDT – First quarter moon.

June 3, 2 p.m. EDT – Venus passes by the sun in inferior conjunction.

(The Learning Center at PARI is a public not-for-profit 501 (c) (3) organization established in 1998. Located in the Pisgah National Forest. The Learning Center provides STEM educational programs at all levels, from K-12 through post-graduate research. For more information about the Learning Center at PARI and its programs, visit http://www.pari.edu.)

 
 

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