Asta's Almanac, is based on Whats Up, Ron? a monthly almanac for Northern American astronomersastras

Astra's Almanac

What's Up in the Night Sky?

August 2012 - Vol. 16, No. 8

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Features: Calendar | Lunar Almanac | Monthly Topic

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.

Links to On-line Almanacs

Starry Trails:
Suzieastro

Abram's Planetarium
Sky Calendar

Classical Astronomy
The Sky this Month

Angular Measurement Review: It is interesting to note that the relationship between the angle subtended by combinations of fingers on your fully outstretched arm are the same for all viewers. This is due to the fact that the hand's size is proportional to the arm's length. A shorter arm is attached to a smaller hand while a longer arm is attached to a larger hand, thus the angle measured remains the same. If you hold your arm fully outstretched, your little finger, when sighted down your arm, is one degree wide. Your three middle fingers is five degrees, your fist, 10 degrees, and the distance between your little finger and your pointer finger is 15 degrees no matter what your age or size.

August boasts of the stars of summer deep in the heart of Milky Way galaxy, bright star clouds and many globular clusters orbiting the galactic center. The dance of the planets continues this month as Mars and Saturn are dancing with the bright stars Spica in the western sky as both head into their conjunction with the Sun ending the reign of this year's planetary oppositions. And what a year it has been! Venus and Jupiter continue their antics in the early morning sky, both will be occulted by the Moon from some locations on Earth this month. (See below.)

MERCURY appears in the morning sky the second week of the month, reaching greatest elongation. VENUS is bright in the morning sky, reaching greatest W elongation mid-month. JUPITER is passing through Taurus and moves in close to the Hyades and Aldebaran. MARS is now past opposition, is setting early in Virgo in the evening sky. SATURN is also in the evening sky and appearing with the first magnitude star Spica, the planet is quickly ending its opposition program and disappears by midnight. Watch Saturn and Mars this month to see how they line up night after night. Their orbital motion will be easy to see if you make a note each night of their positions.

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. Unfortunately some of these events may occur during daylight hours in your area.

DATE EVENT
01
Mars, Saturn and Spica form a triangle in the evening sky. Look for them at sunset.
02
Jupiter 5 degrees N of Aldebaran, look for them in the early morning.
07
The triangle formed by Mars, Saturn and Spica is less than 5 degrees on all sides. This close arrangement won't be seen for Look for them at sunset!
11
The Moon, Venus and Jupiter gather in the morning sky. Jupiter will be occulted by the Moon from some locations on Earth, although not from North America. The island of Hawaii is favorably located, so this event may be witnessed from the United States!
12-13
The Perseid meteor shower peaks. These meteors appear to radiate from the constellation Perseus. Best viewing occurs between midnight and dawn when its radiant is highest. Under favorable conditions observers have reported between 60 to 100 events/hour! The last quarter Moon will be rising after midnight as well, so check the rising time.

The Perseid meteors are the result of dust ejected as Comet 109/Swift-Tuttle has crossed Earth's orbit over many thousands of years. As our home planet crosses the path, the atmosphere rams the particles at about 37 miles/second, causing the streaks of light we enjoy every August.
13
Venus will also be occulted by the Moon this evening, this time the event will be visible in the western United Statues, Japan, Mexico and Eastern Asia. More details are available from IOTA. Mars is 1 degree N of Spica.
14
The evening sky will reveal a straight line formed by Mars, Saturn and Spica just after sunset.
15
Venus at greatest elongation, 46 deg W of the Sun. Earth's sister planet shined at magnitude -4.6 and will appear as a half disk in a telescope or some binoculars.
16
Mercury at greatest W elongation.
17
Mars 3 degrees S of Saturn.
18
Mercury 2 degrees S of the Beehive cluster (M44).
21
Occultation of Spica by the Moon, visible from Antarctica. To observers in the N, it will be 1 degree N of the lunar disk.
22
Mars 2 degrees N of the Moon..
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Lunar Almanac for August 2012

Phases of the Moon Phase and Date(s)

Best viewed before local midnight

new moon icon

New
17

Deep Space Objects
first quarter moon icon

1st. Qtr
24

Planets & Moon
full moon icon

Full
01, 31

Moon
last quarter icon

Last
Qtr 09

Deep Space & Planets

Topic of the month: Cygnus

During the month of August, the constellation of Cygnus, the swan dominates the night sky and the summer Milky Way. High over head after darkness chases away the long summer twilight, the swan flies. The brightest star of the constellation is Deneb, a blue giant that is among the 20 brightest stars in the night sky. A blue giant star, Deneb is designated Alpha Cygni and forms a large triangle known as the Summer Triangle with the bright stars Vega and Altair.

The constellation is thought to resemble a bird. Because it is so far north, it spends a lot of time in the northern sky, visible all year round from northern locations. (Although it may not be visible all night.) If you have trouble seeing a bird, you may resonate with Cygnus's other identify, the constellation is often called the Northern Cross. If you watch the cross all night in August from the northern hemisphere, you will notice that it twists in the sky, so that by the time it sets, it appears to hang upright over the western horizon. It is rather fascinating that the cross will be in this position in the inky evening sky on December 25.

scorpius

Another beautiful star in the constellation is Beta Cygni, known as Albireo. Albireo is a beautiful double star, in a small telescope the stars appear bright yellow and blue. The pair may also be split with binoculars. The central star of the Northern Cross is the second-magnitude star, Sadr, interesting to view in a small telescope. The star fields of the Milky Way between Albireo and Sadr are magnificent. Notable galactic clusters in Cygnus include M29, M39, NGC 6819 and NGC 6866.

The Milky Way in the constellation of Cygnus offers much in the way of bright and dark nebulae, for it is here that the "Great Rift" of the Milky Way begins. This rift is the same dark lane that we can observe in distant spiral galaxies, for the dark material of the rift absorbs light from the stars. It is composed of gas that some day may form new stars in our galaxy. For deep sky observers, Cygnus offers one of the finest supernova remnants known as the Veil Nebula. The star that formed this magnificent nebula exploded over 5,000 years ago, it's spreading debris field now covers over 3 degrees of the sky for Earth based observers. This expanding wreath of gas has two separate designations, NGC 6960 and NGC 6992. The western portion of the veil (NGC 6960) is located near the star 52 Cygni while the eastern portion displays fabulous filamentary structure. For bright nebulae, Cygnus offers NGC 7000, the North American Nebula approximately 3 degrees E of Deneb. So called for it's resemblance to the continent, this bright field may be noted with the naked eye at a dark site. It is often seen in binoculars and a small telescope will yield its brightest jewels.

--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 "Whats Up?" is ©2012 by Dawn Jenkins for Astra's Stargate. View Ron Leeseburg's Farewell Issue

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