What's Up in the Night Sky?

August 2016 - Vol. 20, No. 8

Astra's Star Gate

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 is well placed for the evening twilight sky this month, an apparition that favors observers in the southern hemisphere. VENUS joins Jupiter in the evening sky. Another fine dance this month will culminate on the night of August 27 with a triple conjunction. MARS sets in the late evening, on the 24th will be i in conjunction with Antares when red planet meets red star. A true conjunction with SATURN will occur the next evening. JUPITER moves into Virgo this month. It will be occulted by the moon for observers in the southern hemisphere, details below. SATURN is still located in Ophiuchus, watch the dance of the planets as Saturn appears to overtake Mars this month. URANUS in Pisces, favors observers in the southern hemisphere. The outer planet NEPTUNE in the constellation of Aquarius rises in the evening 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.

04 Venus 3 deg N. of the Moon.

Mercury .6 deg N. of the Moon, occultation from northern New Zealand, Pacific islands, southern tip of South America. This could also be considered a (non-astronomical) conjunction of the two planets, Regulus, and our lunar neighbor.

Regulus 1.7 deg N. of the Moon.

05 Venus 1.1 deg N. of Regulus.
06 Jupiter .2 deg N. of Moon, occultation from eastern Southeast Asia, Papua New Guinea, northern Australia, and Pacific Islands.
10 Moon at apogee, a first quarter moon occurs on this day as well.
12 Unfortunately for the Eastern US, the Perseid meteors will peak around 12 noon on this date. Observers in Asia will be much better off. Under favorable conditions observers have reported between 60 to 100 events/hour! These meteors appear to radiate from the constellation Perseus. Best viewing occurs between midnight and dawn when its radiant is highest. The Moon will be past first quarter, so check the setting time at your location. For east coast observers, the night of the 11th may be better.

The Perseid meteors are the result of dust ejected as Comet 109/Swift-Tuttle has crossed Earth's orbit over many thousands of years. Our atmosphere encounters these particles at about 37 miles/second causing the streaks of light we enjoy every August.

16 Mercury greatest elongation E.
19 Neptune 1.1 deg S. of the Moon, occultation observable from eastern Asia, Alaska, northwest Canada.
22 Moon at perigee.
24 Mars 1.8 deg N. of Antares, with Saturn to the north. These two naked eye planets will be their closest on the night of the 27th.
25 Aldebaran 0.2 deg S. of the Moon occultation from Papua New Guinea, Hawaii, Southern USA, Mexico, and northern Central America.
27 Venus 0.1 deg. N. of Jupiter.
30 The Zodiacal Light or "false dawn" is visible in the E about 2 hours before sunrise. This pyramidal glow is caused by meteoroids, dust particles spawned by passing comets, etc., that have settled into the ecliptic plane (path followed by the Sun, Moon and planets), reflecting the Sun’s light before it rises. This phenomenon will be visible for the next two weeks

Lunar Almanac for August 2016

Phases of the Moon Phase and Date(s) Best viewed before local midnight
new moon New
Deep Space Objects
first quarter moon 1st. Qtr
Planets & Moon
full moon Full
last quarter moon Last Qtr
Deep Space & Planets

Topic of the month: Scorpius

This season the constellation of Scorpius is playing host to 2 naked eye planets, Mars and Saturn, and so it seems fitting that this month's almanac features the stars of the scorpion. The stars of this constellation were long thought to represent the earthly scorpion, a deadly creature that carries a poisonous stinger on its tail. Some astronomers used the scales of the constellation Libra to represent the claws of the scorpion. This will make all of the constellation on the ecliptic animals, thereby creating a zodiac or "circle of animals.", the stars in Libra are actually called the north and south claw. This scorpion in mythology was sent to sting Orion, these two constellation are mortal enemies and never appear together in the sky. Scorpius must set before Orion can rise! In the Chinese culture, this area of the sky has been identified as a dragon, part of the "Azure Dragon of the East.

Classical constellation of Scorpius with the claws from the constellation of Libra

The brightest star of Scorpius is the red giant, Antares, a star that could be a subject of the monthly topic all by itself. One of only two red giant first magnitude stars (Betelgeuse is the other) its apparent magnitude is .96 almost 1. It is a class M0.5 supergiant. Antares is so red its name means, "rival of Mars" or anti-ares. The star was also called "Cor Scorpionis" or heart of the Scorpion by the Romans. This star is also a double star, its greenish companion is only visible in telescopes larger than 6 inches when the separation favors Earth observers. There are many other well-known stars in the constellation, Beta Scorpii is a notable double star, easily separated by a small telescope. Lambda Scorpii, called Shaula, is on the list of the 50 brightest stars in the sky. Its name means "the Sting" This part of the constellation is very low on the horizon for northern observers. The entire constellation of Scorpius appears overhead in the southern hemisphere, providing a great view of some of the finest objects in the summer, er, winter sky. Shaula is a variable star with a period of about five hours, the star varies 1.59 to 1.65 so its variable nature will not be readily evident to the naked eye.

Since the constellation is near to the center of the galaxy, their are many star clusters. Two beautiful clusters, M-6 and M-7 are of the open variety. These are fine binocular objects, but they also look great in a wide field lens of a small telescope. There are also several globulars in the constellation, notably M-4, that may be the closest globular to Earth. M-4 has a bar-like structure that may be noted in small telescopes. It is an old cluster, containing many white dwarf stars. Also notable is M-80, another fine globular. There are many other objects in Scorpius, including dark nebulae. One notable star cluster is NGC-6231 that may have been cataloged by Messier if the constellation was higher in the northern sky. This cluster is surrounded with bright nebulosity that may remind one of the Pleiades. This article features only a few of a large treasury of stars, clusters, and nebulosity in the Scorpius region of the sky. This summer the constellation has been the focus of many star parties due to the presence of Mars and Saturn.

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

The star chart above was generated by Stellarium, a free open source planetarium program. The above image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. Editing was done for educational purposes only. Stellarium offers much more to amateur astronomers and is being used in planetariums and to guide telescopes in the field. Simple charts like the one above can be used on the internet for non-profit, illustration purposes. Proper credit is due of course! Thank you to the makers of this fine program from Astra's Star Gate.

This installment of "What's Up?" is ©2016 by Dawn Jenkins for Astra's Stargate. View Ron Leeseburg's Farewell Issue for information on where to find information such as is presented in this almanac.