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?

July 2012 - Vol. 16, No. 7

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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.

July brings the stars of the Summer Triangle, the galactic center of the in the Milky Way in Sagittarius, and the bright star clouds. Dark skies will reveal the fabulous treasures of the Milky Way as the spiral arms of our galaxy stretch across the sky. This is the time of year that the great birds fly, Cygnus and Aquila whose bright beacons have also guided the sailors across the endless seas before humans invented global positioning or GPS. Keep an eye on the planets because Mars and Saturn are dancing with the bright stars in the evening while Venus and Jupiter continue their antics in the early morning sky.

MERCURY appears in the evening twilight early in the month, but will be lost in the sun by mid-month. VENUS is bright in the morning sky, putting on "part 2" of her inferior conjunction display in Taurus, wandering near the Hyades and Aldebaran. If you are an early morning riser, don't miss this show. JUPITER dances with Venus in the early morning twilight. MARS is now past opposition, is setting early with Regulus 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 as they close their distance and are a mere 12 degrees apart by month end.

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
Mercury at greatest elongation. Enjoy a "quasi-conjunction" early in the morning with Jupiter, Venus, Aldebaran, the Hyades and the Pleiades.
3
Mercury 2 degrees S of the Beehive cluster, aka M44.
5
Earth at aphelion, farthest distance from the Sun. A Pseudo-conjunction of Pleiades, Jupiter, Hyades, Venus and Aldebaran in the morning sky, Venus and Jupiter are a mere 5 deg apart. Keep watching this early morning show!
11
Venus at aphelion.
12
Venus at greatest brillancy, what an inferior conjunction this has been! Venus and Aldebaran are within 2 deg...
14
Venus 4 degrees S of the Moon.
15
Saturn and Spica are within 5 deg of each other this night. Jupiter will be so close to the Moon that some locations on Earth can observe an occultation. Keep watching as Jupiter will pass Aldebaran later in the month.
19
The first moon of Ramadan, can only be seen from the US in Hawaii, the contiguous states will have to wait for the 20th. This is the new crescent that marks the month of fasting in the Islamic calendar.
25
Spica is so close to the moon, that some locations on Earth can observe an occulation,1.4 deg N of the Moon.
28
Mercury at inferior conjuction.
29
Moon at perigee.
30
The Venus-Jupiter show continues, Jupiter passes Aldebaran while Venus passes Zeta Tauri.
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Lunar Almanac for July 2012

Phases of the Moon Phase and Date(s)

Best viewed before local midnight

new moon icon

New
19

Deep Space Objects
first quarter moon icon

1st. Qtr
26

Planets & Moon
full moon icon

Full
03

Moon
last quarter icon

Last
Qtr 10

Deep Space & Planets

Topic of the month: Scorpius

Nothing spells summer in the northern hemisphere like the constellation of Scorpius, a grouping of stars in the shape of the letter "J". The very heart of the constellation is the bright star, Antares. This star has such a deep red color, that it was given its apellation due to the fact that it rivals Mars, or "Anti-Ares." And what a fascinating star it is! It gets its deep red color due to the fact that it is a red giant star, growing 700x larger than our Sun. It is so much larger than our Sun that it would extend out between the orbits of the planets of Mars and Jupiter were it to reside on our solar system. It is a variable sun, glowing from magnitude +0.88 to magnitude +1.16, making it a first magnitude star. In fact it is one of four first magnitude stars that are close to the ecliptic. (The others are Spica, Regulus, and Aldebaran.) It is so close to the ecliptic that it is often occulted by the Moon. Because it is also close to the horizon in the northern hemisphere, this star will seem to twinkle in the sky due to the thickness of the atmosphere that it is seen through from higher latitudes. Beta Scorpii, the star also called, "Graffias", is one of the finest double stars for small telescopes.

The constellation is large and originally contained stars in the constellation of Libra that stands nearby and represents the claws of a giant scorpion. This scorpion was thought to have stung Orion, a constellation that does not appear when it is in the sky. Below Antares, stretching so close to the ground that we need a low horizon to see it, the bright star Shaula is also called, "The Sting". This constellation was known to the Polynesians as the fish hook, a tool that was necessary for the very survival of their culture as fish formed the basis of their diet. In Hawaii, Scorpius was known as Maui’s Fishhook, that was used by the demi-god, Maui, to fish the Hawaiian islands out of the ocean. The Chinese saw the star grouping as a dragon. Please do not call this constellation, "Scorpio." Scorpio is a star sign in the zodiac, not a astronomical constellation.

scorpius

This area of the sky is rich in the cloudy area of the Milky Way. A fine globular cluster, M4 is found very close to Antares. This cluster is also very near to the horizon for the folks based in the northern hemisphere. I also enjoy looking at M80, a more modest globular, that is located higher in the sky and fun to look at on the fourth of July. In addition, two large star clusters, M6 and M7 can be found in the star fields above the Sting and can be detected with the naked eye at a dark site. These two clusters are excellent in binoculars, M7 being much larger and brighter than M6. M7 is thought to contain 80 stars brighter than 10th magnitude and a number of double stars. In addition, the globular cluster M62 is located in Scopius as well as the open star cluster, NGC 6231 that is half a degree north of the star Zeta Scorpii.

The bright stars in this area of the sky are known to belong to an association of stars, gravitationally bound to each other, called the Scorpius-Centaurus Association. Many of the bright stars in the constellations Scorpius, Lupus, Centaurus, and Crux have been identified as members of the “Sco-Cen” association, including Antares and most of the stars in the Southern Cross, the constellation Acrux.  Hundreds of stars have been identified as association members and several star forming regions, such as the Rho Ophiuchi cloud complex located near Antares, the Pipe nebula, and the Coalsack (a dark nebula in the southern skies, visible to the naked eye as big dark patch in the Milky Way star clouds.) This area may well represent part of one of the Milky Way's spiral arms. There is a lot more to be said about the stars, nebulae, and mythology of this fabulous constellation, so dig into the literature, but don't forget to look up and see the fabulous jewels of the summer night sky for yourself.

--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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