What's Up in the Night Sky

August 2019 - Vol. 23, No. 8

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

Bright blue-white Vega (Lyra) shines high overhead as it "leads" the Summer Triangle across the night sky. The "Triangle" is the summer’s most prominent asterism and is made up of three stars: Vega, the brightest, Deneb (Cygnus) and Altair (Aquila). Scorpius and the bright star Antares occupy the southern sky. Look for another famous asterism, “the teapot” (Sagittarius) in the southern sky. The stars of constellations Scorpius and Sagittarius, embedded in the "Milky Way" (part of one of the spiral "arms" of our galaxy), are at their best this month.

MERCURY visible in the evening sky most of the month. VENUS too close to the Sun to be seen until September, reaches superior conjunction on the 14th. MARS too close to the Sun to be seen this month. JUPITER in the night sky will reach its stationary point on the 11th and will continue prograde motion for the rest of the year. SATURN in the evening sky will be noticeable as soon as the sky darkens. URANUS visible in the morning sky, is in the constellation of Aries. NEPTUNE rising in the evening sky, continues retrograde motion as it approaches opposition next month.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
02	Moon at perigee.
08	Venus at perihelion.
09	Jupiter 2.0 deg S. of Moon. Mercury at greatest elongation W. (19 deg.)
11	Jupiter stationary.
12	Uranus stationary. Saturn 0.04 deg N. of Moon, occultation from E. Indonesia, Australia, N. New Zealand, Melanesia and Polynesia but not Hawaii. Pluto 0.1 deg S. of Moon, occultation from NE South America, Ascension Island, central and E. Africa, and S. Arabian Pennisula (Need a large scope for this event!!)
13	Perseid meteor shower peak, this shower produces up to 90 meteors at its peak. Unfortunately, the moon will be approaching full and the meteors will be harder to spot. The Perseid meteors are the result of dust ejected as Comet 109/Swift-Tuttle has crossed Earth's orbit repeatably over many thousands of years. Our atmosphere encounters these particles at about 37 miles/second causing the streaks of light we enjoy every August.
14	Venus at superior conjunction.
17	Moon at apogee.
20	Mercury at perihelion.
21	Uranus 5 deg N. of Moon.
26	Mars at aphelion.
28	Moon .03 deg N. of Beehive cluster (M-44).
30	Moon at perigee, expect large tides. Mercury at greatest heliocentric latitude N. Venus at at greatest heliocentric latitude N.

Lunar Almanac for August 2019

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 30	Deep Space Objects
	1st. Qtr 07	Planets & Moon
	Full 15	Moon
	Last Qtr 23	Deep Space & Planets

Topic of the month: Corona Borealis

The summer night sky brings a small constellation to the northern sky, Corona Borealis, the northern crown. It has no first magnitude stars, in fact most members of this constellation are third magnitude stars but its distinct curved pattern was noted by many cultures. The Greeks called it the Crown of Ariadne, the crown that Bacchus gave to his wife Ariadne and placed it in the heavens after she died. The Australian aborigines called it a boomerang, the Greeks saw it as a laurel wreath. This small constellation of stars can be seen in the summer nights between the constellations of Boötes and Hercules. The Welsh called it "Caer Arianrhod," the Castle of the Silver Circle that was the heavenly home of Lady Arianrod.

The Shawnee Indians also had a special myth about Corona Borealis, they called the constellation "The Celestial Sisters". In this legend twelve beautiful maidens came down from the sky in a silver basket to dance and sing. One night they were seen by a mighty hunter named "White Hawk", who tried to capture the youngest and most beautiful of the maidens, but they leaped back into the basket, and were instantly carried up into the sky. The next night White Hawk returned to the spot disguised as a field mouse. As the maidens danced, he resumed his form and succeeded in catching the youngest maiden and took her home as his bride. They lived together and soon they had a son. The maiden was still a member of the sky people and she became homesick. One day she made a silver basket, and singing a magic chant returned to the sky. She is thought to be the brightest star in the crown, second magnitude star Alphecca, also known as Gemma. White Hawk and his son were so sad after she left that the sky people took pity on them a brought them into the sky as well. White Hawk is thought to be represented by the the bright star, Arcturus, in the nearby constellation of Boötes.

finder chart for Corona Borealis

The stars of Corona Borealis are readily visible to the naked eye at a dark site on a moonless night, however two members of the modern constellation are not often seen, but have an interesting history. They are variable stars. The first is T Coronae Borealis, also called "The Blaze Star. Normally, a star of 10th magnitude, the Blaze Star has shot up to a brightness that rivalled Gemma. Astronomers noted two occurrences, it reached 2.0 magnitude on May 12, 1866 and 3.0 magnitude on February 9, 1946. T Coronae Borealis is an aging red giant star approximately 2,000 light years away. The second star is R Coronae Borealis, a yellow supergiant star, that has been seen to fade by several magnitudes at irregular intervals. It normally shines around 6 magnitude but at irregular intervals (months or years) it may fade down to magnitude 14. It gradually returns to its normal brightness in a few months. This has earned the star its nickname of "Reverse Nova" or the "Fade-Out star." The star is considered to be a carbon star and it is thought that carbon builds up in the star's atmosphere, causing it to fade in brightness. The carbon gas is blown away eventually by the stellar wind or some other mechanism. The approximate position of these variable stars are noted on the finder chart as "R" and "T."

--See You Under the Stars!
Astra for Astra's Almanac