Astroblog: Thursday September 18 to Thursday September 25

Tuesday, September 16, 2025

Thursday September 18 to Thursday September 25

The New Moon is Monday September 22. The Earth is at Equinox on the 22nd as well. Mars is passing through Virgo leaving the star Spica behind. Comet C/2025 R2 is near Spica (binoculars only). On the 24th the crescent moon forms a triangle with Mars and Spica. Saturn is at opposition, when it is biggest and brightest as seen from Earth on the 21st and is visible the entire night. Venus and Jupiter are visible in the morning twilight, Venus is close to the bright star Regulus and the crescent Moon on the 20th low in the twilight.

The New Moon is Monday September 22. The Earth is at equinox, when day and night are of equal length, on the 22nd as well.

Eastern twilight sky on the morning of Saturday, September 20 as seen from Adelaide at 05:43 ACST (30 minutes before sunrise, click to embiggen).

Venus is hard to see deep in the twilight glow. It is very close to the bright star Regulus (zoom into the image to see it), you may need binoculars to see Regulus. The thin crescent moon is close by.

Similar views will be seen from the rest of Australia at roughly the equivalent local time (30 minutes before sunrise).

North-eastern twilight sky on the morning of Saturday, September 20 as seen from Adelaide at 05:14 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 just rising.

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 20 as seen from Adelaide at 19:35 ACST (90 minutes after sunset, click to embiggen).

Saturn is 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 20 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-western sky on Wednesday, September 24 as seen from Adelaide at 19:08 ACST (60 minutes after sunset, click to embiggen). Mars is drawing away from the bright star Spica. The crescent Moon form a triangle with Mars and 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 20 as seen from Adelaide at 19:36 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 new and the fainter clusters and nebula are easier to see.

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

Mercury is lost in the morning twilight.

Venus Venus is hard to see deep in the twilight glow. It is very close to the bright star Regulus, you may need binoculars to see Regulus. The thin crescent moon is close by on the 21st.

Mars is passing through Virgo leaving the star Spica behind. On the 24th the crescent moon forms a triangle with Mars and Spica.

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

Saturn is at opposition, when it is 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