What's Up in the Night Sky

July 2020 - Vol. 24, No. 7

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). In the SW, Arcturus (Bootes) is dropping towards the horizon as Spica (Virgo) vanishes from sight below. Also look for Antares (Scorpius) low in the SW. 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. Look for another famous asterism, "the teapot" (Sagittarius). The "Great Square of Pegasus" asterism, now appears on the E horizon just before the onset of morning twilight. These are the stars of autumn that will take over when the northern summer wanes!

MERCURY emerges from inferior conjunction on the 1st, entering the morning sky and reaching greatest enlongation W. on the 22nd. VENUS prominent in the morning sky reaching -4.7 in the constellation of Taurus. MARS opens the month shining at -0.5 mag. By month's end it will rise at midnight and shine at -1.0 magnitude. JUPITER reaches opposition on July 14, shining at -2.7 in Sagittarius. SATURN also reaches opposition in Sagittarius on July 20. URANUS rises in the morning sky, about halfway between Venus and Mars as from the northern hemisphere. NEPTUNE in Aquarius is in the morning sky.

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
01	Mercury at inferior conjunction.
04	Earth at aphelion, closest to the Sun this year.
05	Penumbral lunar eclipse. Yes, another penumbral eclipse on the same day as last month! Not in the northern hemisphere, but best seen in Argentina, if it can be noticed at all. This month's full moon is called the "Buck" moon because deer are beginning to grow their antlers. Jupiter 1.9 deg. N. of Moon. The full moon is low in the sky during the summer months.
06	Saturn 2 deg. N. of Moon.
08	Mars at greatest heliocentric lat. S.
10	Venus greatest illuminated extent.
11	Mars 2 deg. N. of Moon. Venus at aphelion.
12	Mercury stationary. Venus 1.0 deg. N. of Aldebaran Moon at apogee.
13	Mercury at greatest heliocentric lat. S.
14	Jupiter at opposition. Uranus 4 deg. N. of Moon.
15	Pluto at opposition.
17	Venus 3 deg. S. of Moon.
19	Mercury 4 deg. S. of Moon.
20	Saturn at opposition.
22	Mercury at greatest elongation W. (20 deg.)
25	Moon at perigee.
28	S. Delta Aquariid meteors peak, this shower produces up to 20 meteors at its peak.

Lunar Almanac for July 2020

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 20	Deep Space Objects
	1st. Qtr 27	Planets & Moon
	Full 05	Moon
	Last Qtr 12	Deep Space & Planets

Topic of the month: Virgo constellation

Virgo constellation image created in Stellarium 2020

Virgo is well known as the constellation of the Virgin. Virgo is one of the ecliptic constellations that has a long history. William Herschel noted that there are more deep sky objects in the constellation than there are bright stars. This is because a great galactic cluster is centered in Virgo. The giant galaxies M87 at the heart of the cluster is a galaxy gobbling x-ray source known as Virgo A. Other bright Virgo cluster members include M88, M89, M90, M58, and M84, that are all located in the Virgo constellation proper. It may even be that the Milky Way itself is an outlying member of this galactic supercluster.

Richard Allen in Star Names cites an observation of Saturn by the Babylonians in this constellation back in 228 BC as it passed the gamma star, Porrima. Because it lies in the Mesopotamian "path of the Moon", Virgo was observed regularly. But the constellation's history goes back long before that.

Virgo's brightest star, Spica (magnitude .95) is located very close to the modern ecliptic, in fact less then 2 degrees away from that thin line representing the plane of Earth's orbit. Its proximity to the ecliptic means that it can be occulted by the Moon, and as in 2013 when Spica was occulted 12 times, every time the Moon came near Virgo! The moon passes through Virgo every lunar month.

Spica was identified as a ripe wheat stalk in the hand of the Virgin. Theoretically, she holds a palm branch in her right hand and a stalk of wheat in the left. She celebrates the growing season and is associated with fertility. Sometimes Spica is identified as an ear of corn, that identification I hesitate to make because corn - - that is maize, is a new world product. Corn in the old world was more of a generic term for a food crop.

The star, β Virginis, commonly known as Zavijava is the constellation's 5th brightest star at 3.55 magnitude. It is even closer to the ecliptic than Spica, according to Wikipedia, it will be occulted by the planet Venus in 2069. The gamma star of the constellation is the well-known star Porrima. It is a double star, with two components at 3.65 and 3.56 magnitude. They orbit each other in 169 years, with the line of sight from Earth causes them to change their separation. They were last closest in 2005 and couldn't be split, but in 2020 they are farther apart and can be resolved in a small telescope. The distance between the two stars varies from 5 AU, (about the distance of Jupiter to the sun) to 81 AU at their farthest.

In my studies, I have encountered an abundance of names and designations for the constellation Virgo. It has been equated with Isis, Ishtar, Persphone, Demeter, Diana, Minerva, Fortuna, Bel's wife, barking dogs, a ship, a maiden in a ship and many more. It is known that sometimes the stars on the eastern side of the constellation were placed in the constellation of Libra, helping to form the image of the scale. In ancient Mesopotamia, Virgo was known as "The Furrow" or "Absinnu" in Akkadian, a constellation that celebrated their agrarian culture. It was a land of farming and irrigation. The two great rivers, Euphrates and the Tigris did not offer up their spring floodwaters in synch with the growing season when the crops needed it, so they learned to regulate the waterways. Naturally, Spica represented barley, their most important crop. Barley was their preferred crop because of its tolerance to the briny environment they grew their crops in.

Marduk's tiara, an alternate view of Virgo

Because Marduk was the primary god of the Babylonians, following a commentary on Marduk's Address to the Demons written in the late Babylonian period by a scribe named Shema'ya and translated by John Z. Wee, I have presented here a whimsical dot-to-dot portrait of Marduk's tiara. I have reconstructed this image by rearranging the constellation lines from Stellarium.

I am always sad when the long hours of daylight and twilight in late Spring quickly wash away the winter constellations as the Sun returns to the north. Virgo will continue to rise in the northern hemisphere visible in the early evening through July.

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