Astroblog: Thursday December 16 to Thursday December 23

Tuesday, December 14, 2021

Thursday December 16 to Thursday December 23

The Full Moon is Sunday, December 19. This is an apogee, or "mini" Moon. The earth is at Solstice on the 22nd. Three bright planets are seen forming a line in the early evening sky. Venus forms a line with Saturn and Jupiter in the western evening sky. Venus is rapidly lowering in the sky. Late in the week Mercury joins the lineup low in the twilight. Comet C/2021 A1 Leonard may be visible from the 16th.

The Full Moon is Sunday, December 19. This is an apogee, or "mini" Moon, with apogee occurring on the 18th. The earth is at Solstice on the 22nd, when the day is longest.

Morning sky on December 18 looking east as seen from Adelaide at 4:51 ACDST (60 minutes before sunrise). Mars is low in the twilight, you may need binoculars to see Mars clearly.

Similar views will be seen throughout Australia at the equivalent local time (60 minutes before sunrise, click to embiggen).

Evening sky on December 18 looking west as seen from Adelaide at 20:57 ACDST (30 minutes after sunset). Venus forms a line with Saturn and Jupiter.

The insets shows the telescopic views of Venus, Saturn and Jupiter at this time. Venus is a distinct crescent now. Similar views will be seen throughout Australia at the equivalent local time (30 minutes after sunset, click to embiggen).

Whole sky showing the Moon, Jupiter, Saturn and Venus in a line , December 18, 21:34 ACDST, 60 minutes after sunset (click to embiggen). Orion, Taurus and the Pleiades can be seen above the eastern horizon.

Elsewhere in Australia will see a similar planetary line up that the equivalent time (60 minutes after sunset).

Comet C/2021 A1 Leonard as seen looking west from Adelaide at 21:34 ACDST (60 minutes after sunset) daily from 18 December. Similar views will be seen in elsewhere in Australia 60 minutes after sunset.

Comet C/2021 A1 (Leonard) is this years “Christmas comet”. While not as spectacular as the “searchlight comet” Comet C/2011 W3 Lovejoy, it will be a nice little binocular object. It is predicted to reach magnitude 4 at its brightest but it will be too close to the sun to see, the earliest we can expect to see it in the southern hemisphere is around the 16th, low in the twilight. As it climbs higher we will get better views but it will fade rapidly. More details and printable black and white charts here.

Mercury returns to the evening twilight.

Venus is visible in the early evening when the sky is fully dark. I have been able to see Venus from just after sunset and it is easily seen over 2 hours after sunset, longer if you have a clear western horizon. Venus forms a line with Saturn and Jupiter. It is now a distinct crescent in even small telescopes. venus is now heading rapidly towards the horizon.

Mars is low in the twilight.

Jupiter is readily visible in the western sky when the sky is fully dark. Venus, Saturn and Jupiter form a line in the sky. Jupiter is still excellent in even small telescopes, but the window of telescopic observation is closing as it sets earlier.

Saturn is is still excellent in even small telescopes, but the window of telescopic observation is closing as it sets earlier.

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