August Skies 2007

Introduction:
Summer begins to wind down in August: Each August day has less daylight than the previous one and each August night is a bit longer.  However, Summer’s spectacular stars and constellations remain visible nearly all night.  Also, the Milky Way reaches high overhead at dusk and presents spectacular opportunities for stargazers in dark locations or ones equipped with binoculars or a small telescope.

HIGHLIGHTS!
The Perseid Meteor Shower:  On several mid-month nights Arizona observers may see flaming meteor trails in the sky!  These meteors – sometimes called “shooting stars” – are not falling stars at all but small pieces of debris from an old comet striking the Earth’s upper atmosphere and burning up.  Stranger yet, they appear to radiate from a single point in the sky!  If you follow back the paths of these meteors, August’s Perseid meteors all seem to come from the direction of the northern constellation of Perseus.  This year, the Moon will NOT interfere with meteor viewing. So, if the skies are clear, you may see several dozen meteors per hour the nights of August 11th - 12th and August 12th –13th when the shower is at its peak.  Fewer meteors per hour are predicted for the two prior and one following nights!  City lights can seriously interfere with meteor watching (just as does a bright moon), so observers in dark-sky locations should see more meteors.  Although a few meteors may be seen before midnight, Perseus will be highest in the sky between midnight and dawn during August.

Total Lunar Eclipse:  August’s Total Eclipse of the Moon is another morning event, occurring early on Tuesday August 28th.  The eclipse is visible from all of Arizona.
During a lunar eclipse, the Full Moon travels through the Earth’s shadow. This is the first total lunar eclipse visible from Arizona since October, 2004, so make the most of it!  The show begins about 1:53a.m. and ends approximately 5:22a.m..  The Moon takes about 1 hour to enter (and about another hour to exit) the Earth’s shadow.  That leaves nearly one-and-one-half hours during which the Moon will be in eclipse and the sky much darker than usual – AT FULL MOON!  The first hour, between about 1:53 and 2:53 a.m., the Earth’s shadow line gradually creeps across the Full Moon and darkens it!!  From 2:53 to 4:20a.m., the Moon will be completely inside the Earth’s shadow.  If past eclipses are a guide, the Moon will still be noticeable in the sky, but appears a coppery red color!  The final hour sees the Moon exit the Earth’s shadow and appear Full again.  These events end about 35 minutes before sunrise and about 50 minutes before moonset.

(ECLIPSE WATCHERS:  SEE MORE INFORMATION BELOW on this rare event.)

The Sun: The SUN begins August in the constellation of CANCER the zodiac crab. It moves into LEO on August 10th and spends the rest of August within the Zodiac lion.

The Moon:
3rd QUARTER Moon occurs the afternoon of August 5th in ARIES.
August’s NEW MOON occurs the afternoon of the 12th in LEO.
The 1st QUARTER MOON occurs August 20th in LIBRA.
August’s Moon is exactly FULL at the midpoint of the lunar eclipse the morning of August 28th in the constellation of AQUARIUS.  This means the Moon will appear nearly full on both the evenings of August 27th and August 28th, when it rises just before and just after sunset respectively.

The Moon is seen near two naked-eye planets in August:
MARS: Near the thick crescent Moon the mornings of the 6th in ARIES and the 7th in TAURUS.
JUPITER: The waxing Moon is below Jupiter the evening of the 21st in SCORPIO.

The Moon will be seen close to these prominent stars:
Near the Pleiades star cluster & Aldebaran in TAURUS the morning of the 7th.
Near Castor & Pollux in GEMINI at dawn on the 11th.
Close to Spica in VIRGO the evening of the 17th.
Near Antares in SCORPIO the evening of the 21st.

The Evening Sky:
August 1st’s sunset is about 7:20p.m.. However, the Sun sets 25 minutes earlier, at about 6:55p.m., at month end.

Evening Planets.  Mercury, Venus, Saturn and Jupiter.
MERCURY begins August as a morning planet, but passes the Sun heading Eastward on August 15th and on into the evening sky.   For the rest of August Mercury stays low to the horizon and is very poorly placed for viewing. It will be extremely difficult to spot, even with powerful binoculars or a small telescope.

VENUS begins August very low in the West, and rapidly approaching the Sun. Now in “retrograde motion”, Venus is temporarily moving Westward through the stars.  Venus passes the Sun on the 16th and moves into the morning sky to become by month end, a brilliant “Morning Star” low in the east before dawn.
Venus begins August in the constellation of SEXTANS the astronomical sextant, moves into HYDRA the water snake on the 16th, then into a corner of LEO the zodiac lion on the 23rd, and finally into CANCER the zodiac crab on the 24th, where it remains the rest of the month.
Although Venus remains very bright, it is quite close to the Sun, so is best viewed with binoculars or a small telescope.  Note that since Venus is now between Earth and the Sun, binocular or telescope observers may see it in a very thin crescent phase all month.

SATURN begins August very low in the West at sunset but is also too close to the Sun to be observed.  Like Venus, Saturn also moves westward past the Sun and into the morning sky on August 21st.  However, the ringed planet – unlike speedier Venus – will not rise in a dark morning sky until at least mid-September.  LEO is home to Saturn all month.

JUPITER, the 2nd brightest nighttime object after the Moon and Venus, remains in OPHIUCHUS the zodiac Serpent Bearer, all month.  The giant planet remains fairly low in the sky in August because the Sun’s path in the sky three months hence is also low in the sky this month.  Jupiter sets at 1:30a.m. on the 1st, and two hours earlier at 11:30p.m. on the 31st.

What Else to See?
The Perseid Meteor Shower:  Evening observers are at a disadvantage compared with morning observers, since the constellation Perseus is much higher in the sky after midnight.  If you must view the shower during the evening, look northeast between the horizon and the zenith (overhead) point for to meteor to rise from the northeast direction.  As the evening gets later, and Perseus is higher in the sky, more meteors should be visible in all directions in the sky each hour until dawn.

Dark-sky lunar occultations of several naked eye stars during August are listed here.

Summer Milky Way: August is an excellent month to view star clusters and star/gas clouds in the Milky Way.  Look to the South starting with zodiac constellations SCORPIO and SAGITTARIUS. (Scorpio’s stars appear as curved tail and stinger.)  Just left of the stinger stars are two! compact star clusters, #6 & #7 in Messier’s famous catalog of non-stellar objects. Above these clusters and along the Milky Way, even small pairs of binoculars will reveal a half dozen more fuzzy star and/or gas clouds in the constellations of OPHIUCHUS, SCUTUM, DELPHINUS, AQUILA and CYGNUS.

High overhead at dusk in HERCULES is the bright Messier #13 globular cluster.  Hercules is a faint constellation, but M13 is found on the Western side of a rough square of stars in the middle of HERCULES.

Looking South at dusk, you will see the the red Supergiant star ANTARES in the scorpion’s heart. Just a Moon diameter to the right of Antares is Messier’s object #4”, another large “Globular Cluster” with over 100,000 stars packed into an area of the sky about the size of the Full Moon.  Fuzzy in binoculars, a telescope of 4-inches diameter or larger will show M4’s dozens of individual pinpoint red giant stars surrounded by a “cotton ball” of thousands of unresolved fainter stars.

By 11p.m., CYGNUS (AKA the Northern Cross) will be nearly overhead.  The three brightest stars there are the “Summer Triangle” (VEGA in Lyra & farthest West, DENEB in Cygnus lower to the East, and ALTAIR, in Aquila to the Southeast).

To better find these summertime sky objects, below are links to free star maps you can download over the Internet!

The Morning Sky
August 1st’s sunrise is at 5:45a.m.  Each morning afterward the Sun rises a bit later.  August 31st’s sunrise occurs at 6:05a.m.

Morning Planets:  Mercury, Venus, and Mars.
MERCURY begins August on the far side of the Sun and only 12 degrees from the Sun in the morning sky.  It is a very difficult object to spot on the 1st, but each day moves closer to the Sun and is even more difficult to view. On August 15th, Mercury passes the Sun and moves into the evening sky as an evening planet.

VENUS, in between the Earth and the Sun, appears to move very quickly from day to day. Venus begins August as an evening planet, but moves into the morning sky on the 16th and rapidly distances itself from the Sun. In CANCER for the 2nd half of August, Venus rises in a nearly dark sky on the 31st and is well placed for viewing each day thereafter.  Venus will stay in the morning sky as a brilliant Morning Star for about 9 months, until May, 2008.

MARS is found in TAURUS the zodiac bull all month. It rises at about 12:30 a.m. on the 1st, and each day rises earlier until on the 31st Mars rises at 11:40p.m.  Closer to the Sun and moving faster, Earth is slowly “catching up” to slower Mars as both planets orbit the Sun.  In December, the red planet will be closest to Earth and brilliant in the winter sky.
Since Mars lies near the Milky Way, it also near several stars during the month (including 5th magnitude Omega Tauri between the 15th – 20th).  A small telescope will show these faint stars and allow telescopic observers to follow the planet’s Eastward progress through the stars and note Mars motion as it wanders around the the background stars of the zodiac.

What Else to See?
Moon and Pleiades: The morning of the 13th, the Moon rises just below the Pleiades star cluster in Taurus the Zodiac bull.  Since the Moon is near the winter Milky Way, quite a few faint stars will be eclipsed by the Moon that morning.

Occultation of Mercury by the Moon:  Careful and very experienced telescopic observers can watch the New Moon occult (eclipse) the planet Mercury in CANCER after sunrise the morning of August 12th. Mercury and the Moon will be ABOVE the Sun during this occultation, less than 10 degrees from the Sun, and only about 14 degrees above the horizon at the start of the event. Mercury, on the far side of the Sun, appears in its full phase at this time.  Telescopic observers should setup to keep the telescope in the shade if possible and begin watching a few minutes before 6:30 a.m.  Mercury will reappear from behind the Western edge of the Moon between about 7:45a.m. and 8:00a.m.  If you choose to observe this event, be extremely careful:

BE VERY CAREFUL HOWEVER TO NOT POINT YOUR TELESCOPE AT THE SUN!
VIEWING THE SUN DIRECTLY IN A TELESCOPE WILL CAUSE BLINDNESS!

Occultation of Regulus by the Moon:  Careful and very experienced telescopic observers can watch the Moon occult (eclipse) the 1st magnitude star Regulus in LEO after sunrise the morning of August 13th. Regulus and the Moon will be BELOW the Sun during this occultation, about 9 degrees from the Sun and about 25 degrees above the horizon at the start of the event.
The Moon’s Eastern edge covers Regulus at about 8:40a.m. and Regulus reappears from the Western edge of the Moon between about 9:50a.m. and 10:05a.m.
If you choose to observe this event, be extremely careful:

BE VERY CAREFUL HOWEVER TO NOT POINT YOUR TELESCOPE AT THE SUN!
VIEWING THE SUN DIRECTLY IN A TELESCOPE WILL CAUSE BLINDNESS!

Dark-sky lunar occultations of several naked eye stars are listed here.

The Perseid Meteor Shower:  Morning observers have a much greater chance of seeing Perseid meteors, since Arizona skies are more often clear between midnight and dawn.  The occasional random meteors you ordinarily see at night are tiny fragments of Asteroids, inner solar system materials which never formed into planets. By contrast, predictable shower meteors come from debris evaporated from comets.  If the Earth crosses a comet’s orbit path, we may see a meteor shower.  Most meteor showers occur each year on the same nights, and are named not for their parent comet, but for the constellation that hosts them.  The mid-August meteor shower event occurs each year and is strongest between the 9th and 14th of the month.  Although these shower meteors may be seen in all parts of the sky, when traced backwards the paths intersect in the constellation of Perseus.  That is the direction in the sky where the Earth crosses the comet path.

This year the Moon is very close to the Sun between August 9th to the 14th and will NOT interfere with observing the Perseid meteor shower.  So, if the skies are clear, take a few minutes (or a few hours) to marvel at the Perseid Meteor Shower. Although you may see several Perseid meteors per hour on the evenings of August 9th, 10th and 13th, dozens may be visible per hour on the evenings of August 11th and August 12th.  That is when the Earth crosses nearest the center of the comet’s orbit path. As usual, dark-sky observers have the best chance to witness this event.

Summer Milky Way: As mentioned earlier, the Summer Milky Way is easy to see after midnight, as it reaches high overhead.  It is also cooler in the wee hours, so morning observers are more comfortable outdoors in August. Binoculars or a small telescope will help you pick out many star clusters, star clouds and star/gas clouds by sweeping along the arc of the Milky Way from Cassiopeia in the Northeast to Sagittarius in the Southwest.  (Note the free online star chart below.)

Good Luck Observing!