Looking south
September is a great month for stargazing, because there are so many constellations and objects on view. Three bright stars dominate, in a large triangle covering a large part of the southern sky known of course as the Summer Triangle. (Tip: it’s visible into early winter as well. Remember these balmy nights when you’re shivering in December.) The three stars in question are Vega, the brightest, almost overhead; Deneb, to its left (east), not quite as bright; and Altair, in mid sky, distinguished by companion stars on either side of it. Find those three and you’re halfway there.
Starting with Vega, notice the little quadrilateral of stars which makes up the body of Lyra, the Lyre – the sky’s only musical instrument. When they made up the constellations in ancient times it would have been as important as a violin or guitar today. Now look at Deneb, and make out the giant cross shape which you can call either the Northern Cross or its official name, Cygnus, the Swan. This swan is flying down the Milky Way with its wings outstretched, with Deneb at its tail and a fairly faint star, Albireo, at its head. If you have a telescope, or even powerful binoculars, take a look at Albireo and you’ll see that it’s a double star, of contrasting colours. Typically, people see them as yellow and blue, or more accurately yellowish and bluish.
Altair is in the constellation of Aquila, the Eagle, and it too has outstretched wings, though not as obvious as those as Cygnus. Someone obviously has it in for these two birds, as flying between them is Sagitta, the Arrow. You can pick out its shape in a reasonable sky, though the stars are third and fourth magnitude. Another small but easily seen constellation is nearby – Delphinus, the Dolphin, which also looks like what it’s meant to be. Our Young Stargazers section has a page of information about these two constellations and nearby Vulpecula.
But two better-known constellations down in the lower part of the sky are rather more difficult to see – Capricornus and Aquarius. They’re well known as they are in the Zodiac, the path of the planets, but they have no very bright stars and if you live in a light-polluted area you can hardly see them at all. Capricornus – note the ‘-us’ in astronomical terminology, not Capricorn as in astrology (ugh!) – is a water-goat. Not many of those around these days. Aquarius is a human, the Water-Carrier.
Looking north
Map created using Stellarium software.
The same stars are visible looking north all year round, but their orientation changes month by month. By September the familiar Plough asterism, which many people recognise, is down over to the north-west. The Plough is known as the Big Dipper in North America and La Casserole in France – no translation needed, although Saucepan would do.
Follow its two right-hand stars upward and cheat a bit by veering a little towards the W-shape of Cassiopeia and you come to the Pole Star, Polaris. This is the pivot point of the whole sky, and it remains in almost exactly the same spot the whole year round, so once you have found it from your usual observing location, it will always faithfully be there. For many hundreds of years it was a vital navigational aid for mariners, as it indicates north. However, if you were unwary and picked the star at the other end of Ursa Major, named Kochab, you would sail over 15º off course at this time of year, which could be disastrous.
The stars at the top of this view are overhead, so they join on to the south-looking view at the top of the page. Over to the north-east you can see Capella rising. Contrast its colour with that of Vega which is virtually overhead at this time of year. Capella is a yellow giant star, while Vega is a slightly more blue star than the Sun. The contrast is obvious if you look from one to the other.
Back to August constellations Forward to October constellations