Now that September is here, the nights are getting noticeably longer again. On 1st September, sunset is 20:16 and by 22:25 it is completely dark. The weather in September is usually still mild enough so that you can go out and observe comfortably, although the nights can get chilly so it’s time to start taking out the heavy clothes again. Wrapping up and keeping warm can be the difference between enjoying a nights astronomy and coming inside early.
Sun and Moon
|Date||Sunrise (Irish Time)||Sunset (Irish Time)|
Mercury is in the evening sky early this month but is very difficult to see as it sets very soon after the Sun. At the end of the month it moves to the morning sky and may be visible about 30 mins before sunrise on 30th September very low in the east.
Venus will be in the morning sky in September. It is best seen in the first half of the month when it will rise in the east about 90 mins before the Sun. By the end of the month this will have shortened to 40 mins making it harder to see. Look for the very thin crescent moon close to it on the morning of the 25th about 40 mins before sunrise.
Mars is improving in position again this month. It will rise in the east around 11pm at the start of the month and by the end of the month it will rise around 10pm. At the start of the month is will be close to the Pleiades star cluster Hyades and Aldebaran.
Jupiter is probably the most obvious and best placed planets this month. It will be up for most of the night and will be the brightest star in the south by far. You can’t miss it. On the evening of September 11th, keep an eye out for moonrise around 8.40pm when the Moon and Jupiter will rise together in the east.
Saturn is visible most of the night during September. It will be lower than Jupiter and located in the south. while not as bright as Jupiter it should be easy to spot as there are not a lot of other bright stars in the area.
Stars and Constellations
The above sky chart is for 23:00 on 15/09/2022. You can click on the chart to open a new tab and bring you to Heavens Above. On this website you can generate a custom chart for the time and date you wish. The spring constellations of Leo (the lion) and Virgo (the virgin) are gone with Bootes (the herdsman) now setting in the west soon after sunset.
High overhead are Cygnus (the swan), Lyra (the liar) and Aquila (the eagle). The brightest stars in these constellations are Deneb, Vega and Altair and they make up the Summer Triangle which hangs on high in the sky during September. The misty path of the Milky Way also runs through this area of sky.
In the south at this time of year, is the constellation of Scorpius (the scorpion). This is the direction of the centre of our galaxy, the Milky Way. It never rises very high in the sky from Ireland, but if you look in the direction you should be able to make out that it is almost misty or milky with stars.
The autumn constellations are gaining height in the east early the night and as the night goes on they will rise higher and higher. The great square of Pegasus (winged horse) is visible along side Andromeda (mythical princess). If you live in a very dark location you may be able to see the Andromeda Galaxy with your naked eye. If you have binoculars you will easily pick it out. from the square of Pegasus follow the curve of Andromeda until you get to the T shaped turn. Go to the right here for a short distance to find it. It is the most distant object visible without binoculars or a telescope.