The Major Planets in September 2011

Saturn drops down to become lost in the evening twilight during September while Venus rises a little. The two meet at the end of the month. Jupiter rises later in the evening after Saturn and Venus have disappeared.

Jupiter can also be seen in the morning sky as can Mars. Mercury is too close to the Sun to be seen during September

Uranus is at opposition in Pisces on September 26, so is in the sky from early evening. Neptune, in Aquarius, is in the sky until shortly before dawn.

The 5 naked eye Planets in September 2011

The usual notes on each planet for the month are on the left hand side of each section with a chart on the right.

The charts show the position or path of the planets for the month, unless the planet is too close to the Sun for observation, as is the case for Mercury during September . Stars to magnitude 5 are marked, with magnitudes for those brighter than 3.5 shown without a decimal point. The circle on each chart represents a field 10° in diameter, about the width of the 4 fingers of a hand held at arms length and twice the field of view of most binoculars.

The charts present a view as seen from mid latitudes in the southern hemisphere. The field shown in each chart is about 40° wide and 35° high. Star names are in white, constellation names in green.

All charts have been prepared using GUIDE 8 software published by Project Pluto

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MERCURY in September 2011 (not observable)
Mercury rises in the morning sky before the Sun for almost the whole of September. But at its best, at the beginning of September, only 45 minutes earlier, so it will be too low in the twilight to see. Mercury is at its greatest elongation, 18° west of the Sun on September 3. After that, the planet will move back towards the Sun until on September 29 Mercury is at superior conjunction. The planet, if it could be seen, would then appear to be just over 1° from the Sun. In reality it will be 59 million km beyond the Sun, and 209 million km ( 1.40 AU) from the Earth. Being the other side of the Sun, Mercury will be fully lit, at magnitude -1.6. Thus it would be a bright object if seen in the dark sky. The Sun, though, is at magnitude -26.7, that is 25 magnitudes brighter. This means the Sun appears 10 billion times brighter than the planet. Of course the Sun is also much larger. Its apparent diameter will be almost 400 times that of Mercury, the surface area nearly 160000 times as large.	The chart shows the position of Mercury relative to the Sun as "seen" from New Zealand when at superior conjunction at 8am on 29 September. The distance of Mercury from the Sun is in scale with the diameter of the Sun, but Mercury's size is greatly exaggerated. Do NOT attempt to view Mercury close to the Sun. Permanent eye damage would result.
VENUS in September 2011
Venus is an early evening object throughout September but on the 1st it sets only 15 minutes after the Sun. Thus it is not likely to be seen then. By the end of the month Venus will set about one hour after the Sun, so that 20 minutes after sunset the planet should be visible about 6° above the horizon to the west. At the end of September Venus will move past Saturn. The two are closest on the 29th with Saturn 1.5° to the right of Venus. When Venus becomes visible in the twilight, the sky will too bright to see Saturn, but the latter may be visible using binoculars. On the 28th, the moon, 20 hours after being new and only 1% lit, will be 5° to the left of Venus. 5° is about the width of the field of view of many binoculars which may show the wafer thin crescent before it gets too low in the sky. See the chart for Saturn for their relative position.	The chart shows the path of Venus, in Virgo, from the 10th of September as it moves away from the Sun. Although stars are marked, only one or two of the brightest are likely to be visible shortly before Venus sets, even at the end of the month.
MARS in September 2011
Mars continues to rise in the morning a little over 2 hours before the Sun throughout September. The planet will be moving to the east through the stars, at first in Gemini and then in Cancer from the 16th. Mars remains as magnitude 1.4 so it will be necessary to look for it at least 45 minutes before sunrise. Closer to the time of sunrise the brightening dawn sky will swamp out the planet. 45 minutes before sunrise the planet will be to the northeast with an altitude ranging from 10° in the south of NZ to 16° in the north. The brightest star in Gemini, Pollux β Gem, will be 6° below and a little to the left of Mars on the morning of the 9th of September. Procyon, at magnitude 0.5 the brightest star in Canis Minor, will be 17° away on the other side of Mars. The planet and two stars will form an almost straight line. The crescent moon will be closest to Mars on the morning of the 24th when it will be 7.5° to the right of the planet. The previous morning it will be a similar distance to the upper left of Mars. On the last morning of September, Mars will be on the edge of M44, "Praesepe" or the "Beehive" star cluster. It will cross the cluster between the 1st and 3rd of October.	The chart shows the path of Mars in the morning sky during September 2011. The view shows the sky on the morning of September 24 about 45 minutes before sunrise when the crescent moon will be 6° away to the right of Mars. Early in the month some of the stars near the bottom of the chart up to about the bottom of the 10° circle will be below the horizon 45 minutes before sunrise. They all come into view as the month progresses.
JUPITER in September 2011
During September, Jupiter will be moving slowly in Aries near the its border with Cetus. Its motion will be in a retrograde, westerly, sense as the faster moving Earth begins to overtake Jupiter. At the beginning of September, Jupiter will rise at about 11pm for much of NZ, although quite a bit later in the far south. By the end of the month the time it rises will have advanced by 2 hours. But with the start of NZDT this is about 10pm NZDT. Jupiter will then be readily visible by midnight, the brightest "star" to the northeast. On the night of September 16/17 the 85% lit moon will be 5° from Jupiter. At midnight they will be to the northeast with the moon to the left of the planet. By the morning of the 17th, before sunrise, the pair will be to the northwest, the rotation of the sky bringing the moon almost directly below Jupiter. The star Hamal will be on the opposite side of the moon and just slightly further away. At magnitude 2.0, Hamal is the brightest star in Aries. In mid September Jupiter will be 630 million km, 4.2 AU, from the Earth and almost 5 AU from the Sun.	The chart shows the small movement of Jupiter in Aries during September. Jupiter is marked at its position on September 16/17 when the 85% lit moon will be 5° to the left of Jupiter. The chart shows the orientation of the sky at midnight.
SATURN in September 2011
Saturn sets about 9pm at the beginning of September so will be visible in the evening sky, low to the west, once the sky darkens. It gets steadily lower during September to set soon after 8pm (NZDT) by September 30, not quite an hour after the Sun. As a result, Saturn will become lost to view in the evening twilight during the month. Although the chart makes it appear that Saturn rises slightly, the western sky, stars and Saturn as a whole will be getting lower. At the end of September Venus, moving slowly up in the evening sky during the month, will pass Saturn. The two are closest on September 28 and 29. While Saturn is not likely to be visible to the eye, Venus should be, low to the west, shortly after sunset. Binoculars are then likely to show Saturn. Saturn and Venus are not really close: Venus is 251 million km (1.68 AU) from the Earth on the 28th, but Saturn is 1591 million km away, more than 6 times as far. Both are beyond the Sun which is 150 million km away. On the 28th the moon, a very thin crescent only 1% lit, will be 5° to the left of Venus. Again, having found Venus, it may be possible to see the moon using binoculars. It will be a very challenging observation, as New Moon occurs barely 20 hours earlier.	The chart shows the path of Saturn through Virgo as seen to the west during September. Also shown is the path of Venus during the last few days of the month. Venus and Saturn are marked in their position for September 28 when the one day old moon is 5° left of Venus. The brown band at the bottom of the chart shows the approximate level of the horizon about 20 minutes after sunset on the 28th.