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August 2004 Skies
August 07 , 2004 by George MuncasterThe Evening Sky:
Summer rapidly winds down during August. The SUN begins the month in the constellation CANCER, but moves into LEO on August 10th and spends the rest of the month moving across our Zodiac lion. Early August sunsets happen at about 7:20p.m., but occur 25 minutes earlier by month end.
New MOON occurs on the 15th in the constellation LEO. The next evening a very thin crescent Moon will be close above Mars just after sunset. Full Moon occurs on the 29th in the constellation AQUARIUS, with full moonrise at about 7:15pm.
Low and above the Sun in Leo are three naked eye planets, MARS, MERCURY AND JUPITER. Mars (lowest in the sky and difficult to see) will probably require binoculars. Between August 9 11, Mars passes REGULUS, the brightest star in Leo. On the evening of August 10th, Mars is less than 1 degree (2 Full Moons) away from Regulus, while both are deep in the sunset glare.
Above and to the left of Mars is Mercury, never far from the Sun. Mercury starts the month more than 25 degrees East of the Sun, but races for the Sun, passing about 5 degrees South of the Sun on August 23rd.
Higher above and left of Mercury is brilliant Jupiter. Although slowly moving farther East each day, both Mars and Jupiter are lost in sunset glare by month end. For the next several months no naked-eye planets will be visible in the evening sky.
The Morning Sky:
Sunrise occurs at about 5:45a.m. early in the month and about 20 minutes later at month end. The waning MOON is visible in the morning sky early in August. It rises well to the North of Venus on the morning of August 12th, three days before New Moon.
VENUS, which made a rare and well publicized Transit across the face of the Sun in June is now high and dazzling in the morning sky. All month it rises about 2:30 am, more than 3 hours before the Sun. You will never see Venus much farther away from the Sun than it is in August: Early in the month, Venus rises a bit North of Due East and will be seen squarely in the middle of the four prominent Winter constellations: AURIGA and TAURUS (above Venus), ORION and GEMINI (directly below Venus).
GEMINI also hosts the bright yellow planet SATURN. The two morning planets make quite a show throughout August. Saturn races to catch up with Venus and finally passes the brighter planet at month end: On August 31st these planets will be in “conjunction” (closest approach) less than 2 degrees (4 Full Moons) apart in a dark sky at 4a.m.
At month end, fleet MERCURY rises at 5 am., more than an hour before sunrise. It can be seen beneath and slightly to the North of Venus and Saturn.
What Else to See? August is the best month to view the prominent constellations SCORPIO and SAGITTARIUS. It will be very dark by 9pm, and you should get a great view if you can see close to the southern horizon. Note the curved tail and stinger of the starry scorpion, followed closely by the archer aiming his bow and arrow at the monster. In the scorpion’s heart is the red Supergiant star ANTARES, 16th brightest star in our sky. There are many prominent star clusters and gas clouds in Scorpio and Sagittarius, the brightest half-dozen of which are easily visible in binoculars if you are in a dark sky location.
The center of our MILKY WAY Galaxy lies in Sagittarius, and the August Milky Way arches high and to the left from Sagittarius. By 10pm the constellations of CYGNUS the Swan (aka the Northern Cross) and LYRA the lyre are directly overhead. Cygnus (farther East) is marked by the bright star DENEB (19th brightest), while VEGA (the 5th brightest star) is the only notable star in Lyra (farther West). Across Cygnus from Deneb is ALBIREO (foot star in the Northern Cross). Albireo is a wide double star whose components are of nearly equal brightness, but one star is noticeably purple while the other is orange. By 11pm the Milky Way will be directly overhead and you may see the “dark rift” of absorbing dust cutting lengthwise through the starry Milky Way in Cygnus.
The famous Perseid meteor shower occurs each August, best seen in pre-dawn skies on the evenings of 9-13 August. Unfortunately, in Arizona we rarely see it to advantage: Most years Arizona’s monsoon clouds interfere or even prevent viewing the 50+ meteors per hour seen at the shower’s peak the evening of August 11-12. (We typically have better luck viewing the mid-December Geminid meteors.) This year the Moon will be in the pre-dawn sky: Moonlight brightens the sky and blocks viewing of most Perseid meteors.
Good Luck Observing!
Some additional night sky resources available on the Internet include:
http://antwrp.gsfc.nasa.gov/apod/ap001206.html
(Astronomy Picture of the Day)
http://www.eastvalleyastronomy.org
(East Valley Astronomy Club)
http://www.fourmilab.ch/yoursky/
(Interactive planetarium & star charts)
http://www.skyandtelescope.com
(Sky and Telescope Magazine)
http://www.astronomy.com
(Astronomy Magazine)
http://www.space.com
(Space & Astronomy topics of general interest)
George Muncaster is Principal at Systems 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.
