The Evening Sky in September 2025
Bright stars shine around the skyline. Orange Arcturus is in the northwest, often twinkling red and green as it sets. Canopus, the brightest star in the evening sky, skims along the southern skyline, twinkling all colours. Vega is low in the north. It is the second-brightest northern star after Arcturus. From northern Aotearoa the star Deneb can be seen near the north skyline. It is the brightest star in Cygnus the Swan.
Mars is low in the west. It looks like a medium-bright red star. In mid-September it will be near Spica, the brightest star in Virgo. Saturn is in the eastern sky, a medium-bright ‘star’ all on its own. Late in the month Mercury appears below Mars in the west, setting an hour after the Sun (so isn’t on the chart.)
Orange Antares, northwest of the zenith, marks the body of the Scorpion. The Scorpion's tail hooks toward the zenith like a back-to-front question mark. It is the 'fishhook of Maui' in Māori star lore. Below or right of the Scorpion's tail is 'the teapot' made by the brightest stars of Sagittarius. It is upside down in our southern hemisphere view.
Midway down the southwest sky are 'The Pointers ', Beta and Alpha Centauri. They point down to Crux the Southern Cross. Alpha Centauri is the third brightest star. It is also the closest of the naked-eye stars, 4.3 light-years* away. Beta Centauri, along with most of the stars in Crux, is a blue-giant star hundreds of light-years away.
The Milky Way spans the sky from north to south. It is brightest and broadest overhead in Scorpius and Sagittarius. In a dark sky it can be traced down past the Pointers and Crux into the southwest. To the northeast it passes Altair, meeting the skyline right of Vega. The Milky Way is our edgewise view of the galaxy, the pancake of billions of stars of which the sun is just one. The thick hub of the galaxy, 27 000 light years away, is in Sagittarius. Dust clouds near us appear as gaps and slots in the Milky Way. Binoculars show many clusters of stars and some glowing gas clouds in the Milky Way.
The Large and Small Clouds of Magellan, LMC and SMC, look like two misty patches of light in the south sky. They are easily seen by eye on a dark moonless night. They are galaxies like our Milky Way but much smaller. The LMC is about 160 000 light years away; the SMC about 200 000 light years away.
On moonless evenings in a dark sky the Zodiacal Light is visible in the west. It appears as a faint broad column of light extending up past Mars and Spica, toward Antares. It is sunlight reflecting off meteoric dust in the plane of the solar system.
There are two ‘morning stars’. Golden Jupiter appears in the northeast around 4:20 a.m. at the beginning of the month and 3 a.m. at the end. Silver Venus, brighter than Jupiter, rises around 5:30 at the beginning of September and soon after 5 a.m. at the end. The Moon will be near Jupiter on the 14th, and close to Venus on the 20th.
There is a total eclipse of the Moon around dawn on Monday 8th. The Moon starts to enter the dark part of Earth’s shadow, the umbra, at 4:27 a.m. It is fully in the umbra at 5:31 and closest to the shadow centre at 6:13. It starts moving out of the umbra at 6:53, around moonset from N.Z.
A partial eclipse of the Sun happens at sunrise on Monday 22nd. There will be a big bite out of the Sun when it rises. This will get bigger till 7:10 a.m., then slowly shrink. The Moon moves off the Sun around 8:15, depending on your location. Never look at the Sun without eye protection! Doing so can cause permanent damage. Eclipse glasses are the best protection. If they aren’t available then make pinhole in a sheet of paper or cardboard and project an image of the sun onto a wall. Eclipse glasses can be bought from Astronz, Auckland, www.astronz.nz; Carter Observatory = Space Place, Wellington https://shopwellington.nz/products/0a6f6e36-8b23-11eb-f3d6-6a8b0d828055; the Dark Sky Project, Lake Tekapo, www.darkskyproject.co.nz, and Otago Museum, Samanta.Luzzi@tuhura.nz .
*A light-year (l.y.) is the distance that light travels in one year: nearly 10 million million km or 10^13 km. Sunlight takes eight minutes to get here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes sunlight four years to reach the nearest star, Alpha Centauri.
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