What's Up in the Night Sky

July 2013 - Vol. 17, 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, Denab (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 as the northern summer wanes!

MERCURY reaches inferior conjunction on July 9, and returns to the morning sky around the 20th just before sunrise, but the fantastic show that the folks north of the equator have been enjoying will not be repeated for a while. VENUS visible in the evening sky, but is not a a favorable position for northern observers. JUPITER begins its journey into the morning sky and may be seen just before sunrise. MARS is visible in morning twilight late this month, but may be difficult to see, look for it near Jupiter on the 30th. Mars and Jupiter will also be in the beehive cluster near the dates listed in the calendar below. SATURN is still visible, setting after midnight this month. Deep sky observers will enjoy some of those treasures in the Milky Way without the presence of the bright planets.

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

DATE	EVENT
02	Pluto at opposition. Oops, this will be beyond most of our tiny scopes.
03	Venus in the Beehive Cluster (M44). The queen has arrived!
05	Jupiter 1.1 deg. S of M35. Aldebaran 3.4 deg. S of Moon.
06	Mars 4 deg N. of the Moon.
07	Moon at apogee.
10	Venus 7 deg N of the Moon.
16	Saturn 4 deg. S of M35. Spica .3 deg N. of Moon, occultation visible from Pacific Ocean, parts of S. and Central America.
17	Saturn 4 deg N. of Moon.
21	Moon at perigee will result in large tides, check for local times. Watch the dance between Mars and Jupiter around this date, they pass within 1 deg of each other.
22	Venus 1.2 deg N.of Regulus, Mars .8 deg N of Jupiter.
27	Delta Aquarid meteor shower peak, 20 meteors per hour.
30	Mecury at greatest elongation .

Lunar Almanac for July 2013

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 08	Deep Space Objects
	1st. Qtr 15	Planets & Moon
	Full 22	Moon
	Last Qtr 29	Deep Space & Planets

Topic of the month: Aquila, the Eagle Flies

During the months of Summer in the northern hemisphere the Milky Way galaxy stretches from Sagittarius through Cygnus and beyond. The Cygnus arm of the Milky Way and it's Great Rift provides a startling contrast of bright and dark nebulosity, stars so numerous that they provide milky pathways through the sky. It is here that.a great bird flies. The constellation of Aquila was associated with one of the greatest of all predatorial birds, the Eagle. Some modern observers see an airplane rather than a bird. The location constellation on the celestial equater takes it high across the sky from East to West for observers at northern latitudes..

This sharp-sighted sky bird is dominated by the first magnitude star, Altair. This star is one of the closest bright stars in the sky, a mere 16 light years from our sun. This star is 1.5 times larger than our sun and rotates in a short 6 hours, causing the star itself to be flattened into an elliptical shape. It may be twice as large at the equator as it is a the poles. Altair is flanked by two stars, Alshain (beta) at mag 3.7 and Tarazed (gamma) at magnitude 2.7, making it easy to identify from even a suburban site.

Aquila is located in the summer Milky Way, near the dark rift that is called the Great Rift. Many of the stars in Aquila have long been shining in the galaxy and the constellation is the home of many planetary nebulae. The best of these are NGC 6751 and NGC 6781, they will be challenging but may be worth the reward. Panning through the constellation with binoculars will reveal the dark nebulae that abound in this constellation. For telescopes, the best of these is just west of Gamma Aquilae is B143, with two dark prongs that may been seen in an 8-inch telescope or greater. Nebulae like these are only detectable by the star studded fields they occupy.

Aquila the flying eagle

On June 8, 1918, the Lick Observatory astronomer, E.E. Barnard and the young amateur, Leslie Peltier who was a well-known comet hunter and variable star observer both spotted a nova in Aquila that peaked out at an estimated magnitude of -1.4, V603 Aquilae. An even brighter nova was reported in the constellation in the year 389 that was said to outshine the planet Venus. The constellation harbors many planetary nebula due to the age of the stars located there. The galactic star cluster NGC 6709 at mag 8 contains about 40 stars. Aquila is not close to the center of the galaxy, however, that we can not see other galaxies that are located in the constellation. Notably, the galaxy NGC 6814, at mag 12.2 might be found in a larger amateur instrument.

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