Astronomy: July Skies 2008

JULY SKIES
July is the first full month of Summer. Now the days shorten and the sun rises later each morning AND sets earlier each evening. 

July is an excellent month to observe the Summer stars, constellations and the Milky Way high overhead.  A naked-eye comet (Comet Boattini) should become visible in the morning sky in early July as it moves away from the sun and into a dark sky.

The Sun begins July in the Zodiac constellation of GEMINI the Twins. It remains there until July 20^th, when it enters CANCER the Crab, and remains there for the rest of the month.

May’s NEW MOON occurs on the morning of July 2^nd in GEMINI. The 1^st QUARTER MOON occurs the evening of July 9^th in VIRGO.  July’s FULL MOON occurs near midnight on the 17^th.  On that night, moonrise will be shortly after sunset and the moon rises near Jupiter in SAGITTARIUS.  The Moon reaches 3^rd QUARTER phase the morning of the 21^st in AQUARIUS.

The Evening Sky
Early July sunsets occur about 7:35p.m but sunset on the 31^st will be 12 minutes earlier. 

The Moon: The Moon will be seen in July near four naked-eye planets: MARS on the evening of the 6^th.
SATURN on the evening of the 6^th. JUPITER overnight the 16^th – 17th.

Moon & Prominent Stars:
Very Thin Crescent Moon below Regulus in Leo on the 5^th. 1^st Quarter Moon near Spica in VIRGO the evenings of the 9^th and 10^th. Waxing Moon near Antares in Scorpio overnight July 13^th.

Between the 5^th and 9^th be sure to watch a spectacular conjunction (close approach) of the Moon, bright star Regulus and planets MARS and SATURN. All these objects will set (LOW! in the west ) in a dark sky for the next several days as the conjunction  unfolds.  Note the Moon’s position on the 5^th and 6^th as it passes the other three objects.

First, the Moon passes all three objects. Then, for a few days afterward, skygazers will see a rare alignment of Mars and Saturn with Regulus, the brightest star in the constellation of LEO the Zodiac Lion.

Mars has been approaching Saturn for several months. Watch these planets cross in the evening sky between the 9th and the 11th . Mars then continues eastward and Saturn relatively westward into the sunset glare.

Evening Planets.  VENUS, MARS, SATURN and JUPITER. 
VENUS has now passed behind the Sun, but remains too close to the Sun to be viewed in July. Watch for it to become visible low in the west after sunset in August.

MARS remains in LEO all month. The red planet continues to fade as its distance from Earth increases. Soon it will be lost in the evening twilight. Note that last December Mars was brighter than all other nighttime objects but Venus and the Moon. Now it is significantly fainter than the star Regulus.

View early, since Mars sets at 10:35p.m. on July 1^st, but at month-end, by 9:25p.m.

On July 1^st, Mars passes the 1^st magnitude star Regulus. Note its apparently rapid motion early in the month as it quickly moves past Regulus. On the evenings of July 5^th to 7^th, watch the Moon pass Regulus, Mars and Saturn.

Next, Mars passes Saturn from the 9^th to the 11^th.

SATURN also remains in LEO all month, and also appears westward of Regulus. 

On the 1^st, Saturn sets at 10:47p.m., but on the 31^st, it sets just before 9p.m.  On the evenings of July 5^th to 7^th, watch the Moon pass Saturn, Mars and Regulus. 

Mars passes by Saturn from the 9^th to the 11^th.

JUPITER is July’s brightest visible planet, rising at 7:40 on July 1^st, just 5 minutes after sunset.

The giant planet stays in Sagittarius all month and is above the horizon from its rising until just before dawn all month. A good pair of binoculars will show Jupiter’s four brightest satellites: Io, Europa, Ganymede, and Callisto when most distant from the planet. However, even a very small telescope will easily show them any night!

The Morning Sky
The Sun rises at 5:23 on July 1^st.  On the 31^st, sunrise is at 5:42a.m.

Morning Planets:  MERCURY.
MERCURY begins July rising in a nearly dark sky in TAURUS the Zodiac bull next to the waning Moon. Over the next few days, Mercury briefly passes through the constellation of Orion and on into Gemini on July 11^th.  Use binoculars or a small telescope to watch it pass by the M35 star cluster on the mornings of July 11^th and 12^th. Mercury then quickly moves back toward the Sun and will be lost in the dawn glare by about July 16^th.

What Else to See?
Constellations
The Spring constellations of Virgo, Corvus, and Bootes remain visible overhead and to the west after dark. Hercules appears high overhead and Ursa Major (the “Big Dipper”) is high in the northwest.

View the summer constellations of Lyra, Cygnus, and Aquila to the east, each with a bright star: (Vega, Deneb, and Altair) of the “Summer Triangle”.  When the sky is fully dark, Scorpio the Zodiac scorpion will be seen due South. The bright red star Antares is in the mythological scorpion’s heart.

The summer Milky Way runs from Sagittarius through Aquila and Cygnus and by midnight arches directly overhead. Several fine star clusters and gas clouds (nebulas) are easily seen by slowly scanning the Milky Way with binoculars or a small telescope.

Comet Boattini
This comet was discovered last year at the Mt. Lemmon Observatory near Tucson. While it is of faint naked-eye brightness now, it is an easy to find fuzzy spot in binoculars. In a small telescope, it is larger and faintly greenish in color. Each morning the comet becomes easier to view as it moves away from the sun and higher up in the sky.

Looking east, the comet each day will appear higher and farther from the horizon. On the 1^st, it is very low in western Taurus. By the 10^th it will be near the head of CETUS and by mid-month moves into ARIES, the Zodiac ram.  Sky and Telescope magazine’s website (below) has both small and large star maps you can print out and use to help find this comet.

For best results, look for it between 3:30 and 4:15am near mid-month. After the 20^th, the waning moon will brighten the sky and make comet observing more difficult.

Star Parties
Two public Star Parties are planned in July:
July 10: Phoenix Astronomical Society at Paradise Valley Park, 17642 N. 40^th St., Phoenix
July 11: East Valley Astronomy Club at Riparian Preserve Observatory (adjacent to Gilbert AZ Public Library)

At these star parties, weather permitting, several telescopes are available for public viewing.

Be sure to check the organizations’ websites below for driving maps and up-to-date information.

Good Luck Observing!

Helpful Astronomy Resources on the Internet:
Free July Star Map
Sky and Telescope Magazine online
Phoenix Astronomical Society
East Valley Astronomy Club