September 2011 Sky Events

Moon Phases

Sun., September 4, 1:39 p.m. EDT

First Quarter Moon

The First Quarter Moon rises around 3 p.m., and sets around midnight.

Mon., September 12, 5:27 a.m. EDT

Full Moon

This Full Moon is the one closest to the equinox on September 23, so is this year’s Harvest Moon. Other names are Corn Moon and Barley Moon. In Hindi it is known as Bhadrapad Poornima. Its Sinhala (Buddhist) name is Binara Poya. The Full Moon rises around sunset and sets around sunrise, the only night in the month when the Moon is in the sky all night long. The rest of the month, the Moon spends at least some time in the daytime sky.

Tue., September 20, 9:39 a.m. EDT

Last Quarter Moon

The Last or Third Quarter Moon rises around 11 p.m. and sets around 3 p.m. It is most easily seen just after sunrise in the southern sky.

Tue., September 27, 7:09 a.m. EDT

New Moon

The Moon is not visible on the date of New Moon because it is too close to the Sun, but can be seen low in the east as a narrow crescent a morning or two before, just before sunrise. It is visible low in the west an evening or two after New Moon.

Observing Highlights

All Month, evening

Comet Garradd (C/2009 P1)

Although Comet Elenin has been getting a lot of publicity from the merchants of gloom and doom, there is actually a brighter comet visible with binoculars all month, located in or near the Summer Triangle of Vega, Deneb, and Altair.

Fri., September 9, morning twilight

Mercury close to Regulus

The highlight of the best morning apparition of Mercury of the year for observers in the northern hemisphere is this close approach to Regulus.

Fri., September 16

Ceres at opposition

Ceres, the brightest and nearest dwarf planet, reaches opposition at magnitude 7.6 on the border between Aquarius and Cetus.

Mon., September 26

Uranus at opposition

Uranus reaches opposition at magnitude 5.7 in Pisces.

Thu., September 29, evening twilight

Venus and Saturn in conjunction

Venus is just arriving in the evening sky and Saturn is just leaving, and they pass each other tonight with a slender crescent Moon nearby.

Planets

Mercury is well placed in the morning sky for observers in the northern hemisphere.

Venus reappears in the evening sky towards the end of the month.

Mars spends the first half of the month in Gemini and the second half in Cancer, ending up right in the Beehive Cluster. By the end of the month it has grown to 5.2 arc seconds in diameter and magnitude 1.3.

Jupiter rises in the late evening in Aries, and then dominates the sky until dawn.

Saturn sets soon after the Sun in the constellation Virgo.

Uranus is in opposition in Pisces on September 26, visible all night.

Neptune is well placed in Aquarius all month.

Geoff Gaherty

Starry Night Software