Astroblog: Thursday September 25 to Thursday October 2

Tuesday, September 23, 2025

Thursday September 25 to Thursday October 2

The First Quarter Moon is Monday September 30. Mercury returns to the evening twilight and is close to the star Spica on the 2nd. Mars is lowering in the evening sky as it heads towards Libra. Saturn is just past opposition, and is still visible the entire night. Jupiter is visible in the morning sky near the bright star Pollux. Venus is low in the twilight.

The First Quarter Moon is Monday September 30. The Moon is at apogee, when it is furthest from the Earth, on the 26th.

Western twilight sky on the evening of Thursday, October 2 as seen from Adelaide at 19:00 ACST (45 minutes after sunset, click to embiggen).

Mercury is close to the bright star Spica low in the twilight. You will need a clear, level horizon to see them, and possibly binoculars.

Similar views will be seen from the rest of Australia at roughly the equivalent local time (45 minutes after sunset).

North-western sky on Saturday, September 27 as seen from Adelaide at 19:35 ACST (90 minutes after sunset, click to embiggen). Comet C/2025 R2 (Swan) is just above Mars. The inset is the approximate binocular view of the comet at the time.

Comet C/2025 R2 (Swan) is a (very) recently discovered comet that is around magnitude 7 (binoculars only), but it is well placed near some very bright guide stars so it will be easy to find. It will brighten a bit as it climbs higher into the dark skies, but will not really reach visual magnitude.

For this week it is relatively low above the horizon, and sets an hour after astronomical twilight, so you have a narrow window to observe. More information and printable charts here. https://astroblogger.blogspot.com/2025/09/how-to-see-new-comet-c2025-r2-swan-from.html

Similar views will be seen from the rest of Australia at roughly the equivalent local time (90 minutes after sunset).

North-eastern twilight sky on the morning of Saturday, September 27 as seen from Adelaide at 05:03 ACST (60 minutes before sunrise, click to embiggen).

Jupiter is passing through Gemini and is near the bright star Pollux. Jupiter forms a triangle with the bright stars Procyon and Betelgeuse. Venus is right on the horizon.

The inset is the telescopic view Jupiter at this time.

Similar views will be seen from the rest of Australia at roughly the equivalent local time (60 minutes before sunrise).

Eastern sky on the evening of Saturday, September 27 as seen from Adelaide at 19:41 ACST (90 minutes after sunset, click to embiggen).

Saturn is just past at opposition, when it is biggest and brightest as seen from Earth. Saturn is visible all night long. The inset shows the telescopic view at this time.

Similar views will be seen from the rest of Australia at roughly the equivalent local time (90 minutes after sunset).

North-western sky on Saturday, September 27 as seen from Adelaide at 19:11 ACST (60 minutes after sunset, click to embiggen). Mars is drawing away from the bright star Spica.

Similar views will be seen from the rest of Australia at roughly the equivalent local time (60 minutes after sunset).

Whole sky on Saturday, September 27 as seen from Adelaide at 19:41 ACST, 90 minutes after sunset (click to embiggen).

Mars is in the north-west. Saturn is in the east

Bright Achernar is rising from the Southern horizon. Scorpius is setting in the west and the galactic core is coming off the Zenith.

The Southern Cross is sinking in the Southern sky. The moon is waxing and the fainter clusters and nebula are becoming harder to see.

Elsewhere in Australia will see a similar view at the equivalent time (90 minutes after sunset).

Mercury returns to the evening twilight twilight and is close to the star Spica on the 2nd.

Venus is hard to see deep in the twilight glow.

Mars is passing through Virgo leaving the star Spica behind.

Jupiter climbs in the morning twilight above Venus. Jupiter forms a triangle with Procyon and Betelgeuse.

Saturn was at opposition, when it was biggest and brightest as seen from Earth on the 21st. Saturn is visible all night long.

Printable PDF maps of the Eastern sky at 10 pm AEST, Western sky at 10 pm AEST. For further details and more information on what's up in the sky, see Southern Skywatch.

Star Map via Virtual sky. Use your mouse to scroll around and press 8 when your pointer is in the map to set to the current time.

Cloud cover predictions can be found at SkippySky.

Here is the near-real time satellite view of the clouds (day and night) http://satview.bom.gov.au/

Labels: weekly sky