Royal Astronomical Society of New Zealand

The Evening Sky in October

Download a PDF containing this chart, additional charts for specific areas of the sky and descriptions of interesting objects visible at this time of year.

Jupiter is the 'evening star', appearing in the northeast soon after sunset. It shines with a steady golden light. As the sky darkens Saturn appears north or northwest of the zenith. It has a cream colour, unlike any star.

Jupiter and Saturn are worth a look in any telescope.  Even a small telescope shows Jupiter's disk.  Larger telescopes will show the parallel bands in Jupiter's clouds.  Jupiter's four big moons are lined up on either side of the planet, swapping positions from night to night.  Jupiter is 600 million km from us mid-month. Saturn appears as an oval in a low-powered telescope as the ring and planet merge.  Larger telescopes show the ring and Saturn's biggest moon Titan four ring-diameters from the planet.  Smaller moons are closer in. Saturn is 1400 million km away. The moon will be near Saturn on the 5th and near Jupiter on the 8th and 9th.

Orange Antares marks the body of the Scorpion. The Scorpion's tail loops up the sky in the evening, making a back-to-front question mark with Antares being the dot.  The curved tail is the 'fish-hook of Maui' in Maori star lore. Antares is a red giant star: 600 light years* away and 19 000 times brighter than the sun.   Above and 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.

Canopus is low in the southeast at dusk often twinkling colourfully. It swings up into the eastern sky during the night. Canopus is 13 000 times the sun's brightness and 300 light years away. On the north skyline is Vega, setting in the early evening. It is 50 times brighter than the sun, 25 light years away and the 5th brightest star in the sky.  Places in the north of Aotearoa NZ will see Deneb near the north skyline in the middle of the Milky Way.  Deneb is the brightest star in the cross-shaped constellation of Cygnus the swan. It is one of the most distant stars visible to the naked eye, around 2600 l.y away.  Its brightness is uncertain because of the distance uncertainty but it could be as bright as 200 000 times the Sun's luminosity.

In the southwest are 'The Pointers ', Beta and Alpha Centauri, making a vertical pair. They point down to Crux the Southern Cross.  Alpha Centauri, the top Pointer, is the closest naked eye star at 4.3 light years away.  Beta Centauri is a blue-giant star, very hot and very luminous, hundreds of light years away.

The Milky Way is brightest and broadest in Scorpius and Sagittarius.  In a dark sky it can be traced down to the south. In the north it meets 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. The actual centre, with a black hole four million times the sun's mass, is hidden by dust clouds in space. Its direction is a little outside the Teapot's spout. The nearer 'interstellar' clouds appear as gaps and slots in the Milky Way.  The dust and gas has come from old stars that have thrown much of their material back into space as they faded or blew up. New stars eventually condense from this stuff.  A scan along the Milky Way with binoculars shows many clusters of new stars and some glowing clouds of left-over gas. There are many in Scorpius and Sagittarius and in the Carina region.

The Large and Small Clouds of Magellan, LMC and SMC, look like two misty patches of light in the southeast sky above Canopus. They are easily seen by eye on a dark moonless night.  They are galaxies like our Milky Way but much smaller. The LMC is around 160 000 l.y. away; the SMC around 200 000 l.y. away.

On moonless evenings in a dark rural sky the Zodiacal Light is visible in the west.  It looks like late twilight: a faint broad column of light reaching up toward Antares, fading out at the Milky Way. It is sunlight reflecting off meteoric dust in the plane of the solar system. The dust may have come from a big comet, centuries ago.

Orange Mars rises in the northeast around midnight (so is not on the chart.) It is the brightest 'star' in that part of the sky and makes a triangle of orange stars with Betelgeuse and Aldebaran.  Mars is half the diameter of Earth and 105 million km away mid-month so is small in a telescope, a bit smaller than the globe of Saturn.  It won't look much bigger when we pass it by in December.  The Moon is near Mars on the mornings of the 15th and 16th.

*A light year (l.y.) is the distance that light travels in one year: nearly 10 million million km or 10^13 km. Sunlight takeseight minutes to get here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes four years to reach the nearest star, Alpha Centauri.

Notes by Alan Gilmore,
University of Canterbury's Mt John Observatory, 
P.O. Box 56, 
Lake Tekapo 7945,
New Zealand.