Arizona Skies – JULY SKIESBy George Muncaster
July is the first full month of Summer. Nevertheless, we are past the Summer Solstice (June 21st), so all this month the length of the day shortens: Each July sunrise occurs later in the morning, and each July sunset is earlier than the previous one.
The brilliant winter stars we have been observing in earlier months are now gone. We now can view the last of the spring stars in the West after sunset. Also, Summer’s spectacular stars and the summer Milky Way are now visible. During July, morning observers can see the Autumn stars in the sky before dawn.
During early July you can observe a grand show: For several days, Mercury, Saturn, Mars, the star Regulus, the Moon, the star Spica, and Jupiter are all lined up along a band stretching from the sunset point up and to the left (South) in the Western sky just after sunset:
– Mercury is best seen in binoculars and will be quickly lost in the glare of the setting Sun
– Saturn also sets earlier each evening
– Mars continues to move away from Saturn and approaches Jupiter
– Jupiter continues to dominate the night sky high in the South after dark
Venus remains our brightest planet as a “Morning Star” low in the East before dawn throughout the month.
The SUN begins July in the Zodiac constellation of GEMINI the Twins, where it remains until July 20th, when it moves into CANCER, the Crab.
Sunset on July 1st occurs at 7:38p.m. On July 31st sunset occurs at 7:24p.m.
Sunrise on July 1st is at 5:26a.m. July 31st’s sunrise is at 5:44a.m.
The MOON begins July as a waxing 6-day-old crescent in the constellation of LEO, the Zodiac lion.
July’s 1st Quarter MOON occurs on July 3rd in VIRGO.
The FULL MOON will rise shortly after sunset on July 10th in SAGITTARIUS and it rides low in the sky all night.
The 3rd QUARTER Moon occurs on July 17th in PISCES, when moonrise is at about 11:45p.m.
July’s NEW MOON happens later on July 24th in CANCER.
July’s Moon will pass near three naked-eye evening planets:
JUPITER: Closest to the Moon on the 5th in LIBRA.
SATURN: Near a 1-day-old “baby” Moon the evening of the 25th in CANCER.
MARS: Just below the Moon in the Northwest the evening of July 27th in Leo.
The Moon also passes close to three prominent Stars this month. Note the:
Waxing crescent Moon is near Spica in VIRGO on the 3rd and 4th.
Waxing Gibbous Moon passes very near Antares in SCORPIO overnight July 7th.
Waning Crescent Moon west (right) of Regulus in Leo on the 26th.
Waxing crescent Moon is again near Spica in VIRGO on the 31st.
The Evening Sky
Evening Planets. Mercury (seen only early in the month), Saturn (also an early July object), Mars and Jupiter.
Mercury begins July very low in the Northwest and moves closer to the Sun each evening. On the 1st, it sets 75 minutes after the Sun and may only be visible for a few evenings to observers using binoculars. Look for Mercury about 30 minutes after sunset about 10 degrees left of the sunset point. One way to find the planet is to first find Mars (bright, reddish and higher in the western sky). Then locate Saturn below and to the right of Mars. Mercury can be found below and to the right of Saturn about the same distance away from Saturn that Saturn is below and to the right of Mars. After the first week of July, Mercury and Saturn will be lower and harder to spot.
Saturn also fast approaches the Sun. By mid-month, it will be located with respect to the Sun where Mercury was on July 1st. By month-end, Saturn will be invisible until late-August, when it emerges in the dawn as a morning planet.
Mars remains in the evening sky all month. On the 1st, Mars sets at 9:55p.m., more than two hours after the Sun. By month end, Mars sets at 8:50 p.m., and is no longer in a dark sky. You can appreciate how quickly Mars is moving with respect to the background stars by noticing Mars’ position during the 2nd half of July as Mars rapidly overtakes and passes the 1st magnitude star Regulus in Leo. The planet and star stand closest together on the evening of July 21st.
Jupiter, the brightest object in the night sky after the Moon, stands in western Libra each evening in July. For several months Jupiter has apparently moved to the west as our faster Earth has passed slower Jupiter as they orbit the Sun. In July this giant planet again to slowly move eastward through the stars.
A pair of binoculars or a small telescope shows that Jupiter is itself orbited by four prominent satellites (two are larger than our Moon). Each evening these moons appear to change positions, as they orbit Jupiter and alternately pass in front of, and are then eclipsed by the giant planet. Jupiter’s large and persistent super hurricane (AKA the “Great Red Spot”) is easily visible to observers using a moderate sized telescope.
This July consider making a “field trip” to a scheduled star party at an East or West Valley location. (See below for more information.) These star parties feature many helpful amateur astronomers and several larger telescopes are available for viewing July’s planets and the summer skies. If you want to learn how to use a telescope (whether or not you already own one), plan to attend the FREE TELESCOPE WORKSHOP at Bookman’s Backdoor Bookstore on Sunday, July 9th (RSVP and other information below in the Helpful Resources Section).
What Else to See?
The Summer constellations rise earlier each evening and are conveniently visible all night during July. The sky will be quite dark by 9:00p.m., so early July’s moonless evenings are excellent times to view the night sky.
The “Summer Triangle” of bright stars are a good place to begin: The Summer Triangle consists of Vega, in Lyra the lyre (this brightest summer star is fainter only than Venus and Jupiter); Altair in Aquila the eagle; and Deneb in Cygnus the Swan (aka the “Northern Cross”).
Look for Vega high in the Eastern sky after dark. Below Vega is Deneb in Cygnus. To the right (South) of Deneb is Altair in Aquila the eagle. Another distinctive July constellation is Scorpio the zodiac scorpion. By 9:30p.m. Scorpio’s “tail” and “stinger” stars are above the Southern horizon. Observers with binoculars or a small telescope can view two dense star clusters a bit to the East (left) of the scorpion’s tail.
As the Moon slowly moves from West to East around the Earth each month, it occasionally occults (or eclipses) background stars. Here is a list of brighter stars eclipsed by the Moon in July. A very interesting sequence of occultations occurs early on the morning of July 20th: The waning crescent Moon has occulted many stars in the prominent star cluster, the Pleiades. Two bright Pleiades stars (named Pleione and Atlas) will reappear from behind the dark limb of the Moon just after moonrise at about 1:20a.m. See the list above for additional July occultations.
The Morning Sky
The waning (post-Full) MOON is seen in morning July skies from the 11th through the 23rd. The Moon is near the planet VENUS on the mornings of July 22nd and 23rd.
Morning Planet: VENUS.
Venus begins July in TAURUS, briefly moves into ORION on July 17th & 18th, continues on into GEMINI on July 19th, where it remains for the rest of the month. This white planet remains bright and therefore highly visible, throughout the month even though it is moving eastward toward the dawn sky and the Sun.
On July 1st Venus rises about 3:30a.m., about 2 hours before sunrise. It rises almost 30 minutes later (at about 3:55a.m.) on the 31st.
During July, Earth continues to lag behind faster Venus as they orbit the Sun. Soon, Venus will be so far away from Earth that it will be behind (actually, on the far side of) the Sun. This means Venus continues to shrink in size as viewed in a telescope. It will become progressively closer to the Sun each morning until it is behind the Sun (and farthest from the Earth) in late October.
Lunar Occultation of Pleiades stars: The waning Moon rises very near the Pleiades the morning of July 20th. Before moonrise, the Moon has spent several hours eclipsing many Pleiades stars for observers east of Arizona. However, after moonrise Arizona observers with binoculars or a small telescope can watch several Pleiades stars reappear from behind the dark limb of the Moon VERY shortly after moonrise.
Start by observing moonrise. The waning Crescent Moon rises at 1:19a.m. Note the Moon will rise 30 degrees NORTH (LEFT) of Due East as seen from Central Arizona! Four fairly bright Pleiades stars will soon reappear from behind the Moon’s dark western edge between 1:25a.m. and 1:40a.m. Of course, this event requires observing where you have a clear view of the horizon! Times are given here.
What Else to See? The Summer Milky Way is even more spectacular after midnight during July, as it arches high overhead. Since it is also cooler in the wee hours, morning observers are most fortunate in July. Those with binoculars or a small telescope can pick out many star clusters, star clouds and gas clouds (nebulae) by sweeping along the arc of the Milky Way from Cassiopeia in the Northeast to Sagittarius in the Southwest.
The Moon will either occult or approach very close to several stars of 6th magnitude or brighter during July mornings. Specific times for these events are given here.
Good Luck Observing!
Helpful Astronomy Resources
Star Parties: July 3rd and August 7th at the Glendale Public Library: (623) 930-3530
July 8th and August 5th at the Challenger Space Center: (623) 322-2001
July 14th and August 11th at the Riparian Preserve near the Gilbert, AZ
Public Library. Questions? email: firstname.lastname@example.org
FREE Telescope Instruction Workshop, Bookman’s Backroom Bookstore,
8034 North 19th Avenue, Phoenix (at Northern). Sunday July 9th, 4:30-9:30 p.m.
RSVP REQUIRED by NOON, Friday, July 7th to: RodSutter@yahoo.com
Internet Resources: Free July Star Map
August 07 , 2004 by Kathleen Gorden
George Muncaster is Principal at System Synergies, LLC, a systems engineering firm serving the wireless community and aerospace-defense communities. He teaches astronomy at Glendale Community College and at Scottsdale Community College, and also astronomy distance learning classes at Rio Salado College.
George followed up an early interest in astronomy by obtaining degrees in Astrophysics and in Astronomy at Indiana University and the University of Arizona, respectively.
His related interests include observational astronomy and orbital mechanics. In the U.S. Air Force, he managed R&D acquisition contracts supporting National space systems and served as a Master Instructor for radar sensor systems, orbital analysis, and atmospheric re-entry physics.
He has published over twenty-five papers dealing with systems engineering, systems security, radar systems and astronomical research, and coauthored a U.S. Air Force textbook on radar systems. He holds five U.S. patents in the areas of space systems and wireless communications.
George Muncaster can be reached via email at: astronomer @ evliving.com.
Editor’s Note: George Muncaster is a frequent contributor whose articles are featured under Astronomy.
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