TRADITIONALLY, September was the month when the crops were harvested; a time of year that was vital to local economies across the country.

Harvesting the crops as quickly as possible was crucial in ensuring that people had enough food for winter. This is why the full moon we see this month is probably the best known of all: the Harvest Moon.

At this time of year, when the Sun sets, the Moon rises, which in pre-mechanised times meant that when farmers were harvesting they were not restricted to the normal hours of daylight.

In medieval times all the harvesting was done by hand so it took much longer than methods used today. The moonlight allowed people from entire villages to work throughout the night. (Of course, the Moon does not shine, so when we refer to ‘moonlight’ we really mean reflected sunlight).

The extra light a couple of days either side of full moon meant that the farmers would hopefully harvest enough to survive the coming winter and have enough to sell at the markets, which at this time were the lynch pins of the economy.

The nights are noticeably drawing in. September is a transition month for the night sky, when the summer’s bright constellations start to give way to autumn’s finest, primarily the constellation of Pegasus. By mid-month, the sight of the Great Square of Pegasus clear of the eastern horizon as darkness falls is a sure sign that autumn is upon us, with the promise of cooler evenings.

We are not completely done with the summer stars however, as the Summer Triangle of Altair, Deneb and Vega still dominates the early evening sky.

Vega, in the constellation of Lyra the Lyre, is still very high but no longer overhead; Deneb, in the constellation of Cygnus the Swan, is now at its highest being nearly overhead, while the most southerly of the three stars, Altair, in the constellation of Aquila the Eagle, can still be seen easily but is now somewhat lower in the sky.

The other bright star of the summer skies, the red star Antares in the constellation of Scorpius the Scorpion, has now set.

A large part of the south western sky is occupied by the large but faint constellations of Hercules, Ophiuchus the Serpent Bearer and Serpens the Serpent. As the month progresses and these constellations move towards the horizon, they will be replaced in the south by the equally faint constellations of Capricornus the Sea Goat and Aquarius the Water Bearer.

The Plough, also known as Ursa Major, or the Great Bear (and to the Americans the Big Dipper) is now getting lower in the northern sky, which means of course that the ‘W’ of Cassiopeia is getting higher.

These two groups are on opposite sides of the North Star, or to give it its proper name, Polaris. To find Polaris, start with the two stars furthest from the handle of the plough and draw a line from the right hand star through the left hand star. If you then continue the line you will come to the North Star. If the line is continued further, you reach Cassiopeia.

The Plough is one of our signpost constellations in the night sky and by using the three stars of the handle and curving round and down it is possible to see, low in the north west sky, the bright orange star Arcturus, which has been visible since spring. This will be the last month when you can see Arcturus this year.

Capella, in the constellation of Auriga the Charioteer, is now becoming more prominent in the northern sky. In the winter months Capella will occupy the overhead point in the sky which is marked by the bright star Vega during the summer months.

The Planets in September: The two gas giants Jupiter and Saturn can be seen throughout the evenings. Jupiter rises at about 9pm and can be seen as a bright white spot. To the left and lower in the south is Saturn which rises earlier in the evening. Saturn is not as bright as Jupiter but because there are no bright stars near it is easy to find.

Venus can easily be seen if you are prepared to be up before the Sun rises this month. The other naked eye planets Mercury and Mars are too close to the Sun to be seen.

Meteor Showers: There are no major meteor showers predicted for this month.

Phases of the Moon for September: September 6 Last Quarter; 15 New Moon, 22 First Quarter; 29 Full Moon There are two interesting planet/moon sights this month. On the night of September 5/6 the Moon can be seen very close to Jupiter. On September 27 the Moon can be seen just below Saturn.

The Autumn Equinox: On September 23 the Autumnal Equinox occurs, marking the start of autumn in the northern hemisphere and of spring in the southern hemisphere.

The word equinox comes from the Latin words, aequi, which means 'equal' and nox, which means 'night'. At this instant the Sun lies above the equator and both poles of the planet are illuminated, meaning that on this day the length of daylight and night time are the same.