September ushers in a beautiful transition into spring, where the sky becomes increasingly rewarding as the evenings grow warmer and the wildflowers begin to bloom.

The Milky Way is still spectacular when the Moon is not visible.

In Australia, spring officially begins on 1 September, but astronomically, it begins at the vernal equinox.

This year, the equinox occurs at 4:20 am AEST on Tuesday, 23 September, marking the time when the Sun crosses the celestial equator and day and night are approximately equal.

We will explore the equinox further in an upcoming blog.

Times provided are for Coonabarabran, NSW (AEST), which will be consistent across much of Eastern Australia.

The Moon this Month

• Full Blood Moon: 4:08 am, 8 September 
• Last Quarter: 8:32 pm, 14 September 
• New Moon: 5:54 am, 22 September 
• First Quarter: 9:53 am, 30 September 

The Moon will reach perigee - its closest point to us in its elliptical orbit around Earth - at 10:00 am AEDT on 10 September 2025, at a distance of merely 364,777 kilometres.

This month, the Full Moon will be a ‘Blood Moon’ or lunar eclipse, visible over most of Australia. You would have read about it earlier.

Planets 

Mercury will be visible extremely low in the eastern sky during the latter half of the month, situated within the constellation Leo.

To find it, look in the direction of sunrise for the faint, yellow-white planet.

It will reach its greatest elongation (the farthest distance from the Sun) on 22 September, making it the best time for observation in the eastern sky, approximately one hour before sunrise, provided the horizon is clear. 

Venus shines brightly as a morning "star," rising well before dawn in the eastern sky.

This planet is the most luminous object visible before daybreak and can be seen for most of the month.

You will find it in the constellation Cancer at the beginning of the month and transitioning to Leo by the end.

Venus and Jupiter in morning sky before Sunrise. From Stellarium.

Mars can be spotted early in the month within the constellation Virgo.

Look low in the western sky after sunset for the red planet, which will become lower and increasingly difficult to find as the month progresses.

Jupiter appears brilliantly in the constellation Gemini during the morning sky.

The best time to view it alongside Venus is around 5:00 am AEDT, with an excellent photo opportunity on 16 September when a 30%-lit waning crescent Moon accompanies it.

Jupiter and the Moon on September 16. From Stellarium.

Saturn is observable in the evening sky within the constellation Pisces, moving to Aquarius by the month's end.

This period offers the best chance for viewing as it will be at opposition (closest to Earth), visible all night and throughout the rest of the year.

At opposition, Saturn’s rings are tilted by two degrees relative to terrestrial observers, which is quite narrow.

From Earth, Saturn’s rings appear nearly edge-on.

In March 2025, when we last crossed the plane of Saturn’s rings, they temporarily seemed to vanish. 

Saturn in the early evening sky in the east. With a pair of binoculars you should also be able to see blue Neptune as well. From Stellarium

Meteor Activity 

The month begins with the minor Alpha Aurigids meteor shower. From southern latitudes, the display is modest; you might see a handful of meteors an hour around 3:00–4:00 local time under dark skies.

Face north-east near the bright star Capella and allow your eyes to adjust.

As spring unfolds, the skies will provide a delightful mix of planetary activity and deep-sky opportunities.

Enjoy your stargazing!

Donna The Astronomer