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Tue09162014

Last updateWed, 27 Aug 2014 10am

Astronomy

Mars forms colorful pairs with other objects in the southwest evening sky in September, as the red planet moves from just more than 5 degrees from yellowish Saturn on Sept. 1, to within 5 degrees of red Antares from Sept. 22 through Oct. 3.

Saturn, with its rings tipped 22 degrees from edge-on, is impressive through a telescope, if you catch it before it sinks low.

The crescent moon near a planet is an attractive sight. Catch a waning crescent near Jupiter at dawn on Sept. 20, and a waxing crescent very near Saturn on Sept. 27. On Sept. 27 and 28, Mars passes 3 degrees above Antares, and on the 29th, the lunar crescent passes above the red pair.

September 2014 at dusk: The five brightest objects in evening mid-twilight (ignoring Mercury, near magnitude 0, but very low in the west to west-southwest), are Arcturus and Vega (0.0); Saturn (+0.6); Mars (+0.6 to +0.8); and Altair (+0.8).

Saturn is in the southwest to west-southwest, lower as the month progresses. Mars starts this month just more than 5 degrees to the lower left of Saturn, and 18 degrees to the right of Antares, heart of Scorpius the scorpion. Watch Mars move! On Sept. 5 and 6, look for a nearly vertical “fence” of three stars about midway between Mars and Antares; it marks the head of the scorpion. By Sept. 12, Mars is equidistant from Saturn and Antares, 11 degrees from each. On Sept. 17, Mars passes just a half-degree north of second-magnitude Delta Scorpii, the middle star of the “fence.” Mars passes 3 degrees north of Antares on Sept. 27 and 28, with a crescent moon nearby on the next evening. Compare color and brightness of Mars and Antares (“rival of Mars”) for several evenings around their closest approach. Mercuryis highest at midmonth, but only 3 degrees up in mid-twilight from Southern California in this poor apparition. It passes 0.6 degrees south of Spica on Sept. 20. Binoculars, very clear skies and an unobstructed horizon are needed to observe this event.

As for stars, Spica departs in the west-southwest. Arcturus remains prominent in the west, and Antares sinks toward the southwest. Vega, the lead star of the Summer Triangle, passes nearly overhead, with Altair and Deneb remaining east of the meridian (north-south line overhead) at mid-twilight through September. Fomalhaut rises in the southeast at month’s end.

Moon in the evening sky is found near Mars and Saturn on Aug. 31; near Antares on Sept. 1; near Saturn on Sept. 27; and near Mars and Antares on Sept. 29. On evenings following the full moons of late summer and early fall, we usually get a “Harvest Moon effect,” when the moon rises not very much later each evening. But this year, the perigee on Sept. 7 and the low inclination of the moon’s orbit increase the daily time delay over what it can be for the Harvest Moon in most years.

September 2014 at dawn: The brightest objects are Venus, near magnitude -4, but in bright twilight and sinking out of sight at our mid-twilight viewing time during third week; and Jupiter, near magnitude -1.8 and climbing in the east. Next in brightness are Sirius, in the southeast to south-southeast, and Capella, nearly overhead.

The latter two are the southernmost and northernmost stars of the huge “Winter Hexagon,” in clockwise order, Sirius, Procyon, Pollux (and Castor, not shown), Capella, Aldebaran, Rigel and back to Sirius. Betelgeuse, Orion’s shoulder, resides within the hexagon. Regulus, the heart of Leo the lion, follows the hexagon across the sky, as if to chase his next meal, with the twins of Gemini, Orion, two dogs, Auriga the charioteer, Capella the mother goat, and Taurus the bull as possible menu options. Find emerging Regulus just 0.8 degrees south (to the lower right) of Venus on Sept. 5. The only other star of first magnitude visible in September’s dawns is Deneb in the northwest, the last star of the Summer Triangle to set.

Before morning twilight brightens, use binoculars to find the Beehive star cluster, 3 degrees above Jupiter on Sept. 1, widening to 8 degrees to the upper right of Jupiter at month’s end.

The moon in morning sky appears near Aldebaran on Sept. 14 and 15; widely (11 degrees) north of Betelgeuse on Sept. 16; between Procyon and Pollux on Sept. 17; south of Jupiter on Sept. 20; and within 5 degrees south of Regulus on Sept. 21.

Check the website of the Astronomical Society of the Desert for dates, maps and directions to our “star parties,” where everyone is welcome to look through our telescopes at the moon, planets and “deep sky objects.” Year-round monthly sessions begin at dusk at Sawmill Trailhead, elevation 4,000 feet. This month’s session will be on Sept. 20, if sky conditions permit. Our monthly star parties at the more-convenient Santa Rosa and San Jacinto Mountains National Monument’s Visitor Center will resume on Oct. 4.

Enjoy the sky!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller, who provided the twilight charts, did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.