Astroblog: December 2023

The Last Quarter Moon is Thursday, January 4. Earth is at perihelion, when it is closest to the Sun, on the 3rd. Saturn is now in the west when twilight ends. Jupiter is highest around nautical twilight and is now well visible in the evening sky. Venus is visible in the morning twilight.

The Last Quarter Moon is Thursday, January 4. The Moon is at apogee, when it is furthest from the earth, on the 2nd. Earth is at perihelion, when it is closest to the Sun, on the 3rd.

Evening sky on Saturday, December 30 as seen from Adelaide at 22:18 ACDST (90 minutes after sunset), Saturn is above the western horizon. The inset is the telescopic view of Saturn at this time.

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

Evening sky on Saturday, December 30 as seen from Adelaide at 22:18 ACDST (90 minutes after sunset). Jupiter is above the northern horizon.

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

Morning sky on Saturday, December 30 as seen from Adelaide at 04:57 ACDST, (60 minutes before sunrise, click to embiggen). Venus is beginning to lower in the morning twilight and is heading towards Scorpius. The inset is the telescopic view of Venus at this time.

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

Whole sky on Saturday, December 30 as seen from Adelaide at 22:17 ACDST, 90 minutes after sunset (click to embiggen). Saturn is setting in the north-west, and Jupiter is high in the north.

Sagittarius is almost set. Orion is rising in the east.

Between the bright star Canopus and the Southern Cross are another wealth of binocular objects to discover.

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

Mercury is lost in the twilight.

Venus is high in the morning twilight, it will now sink towards the horizon but will remain easily visible for all of November.

Mars is lost in the twilight.

Jupiter is highest around nautical twilight and is now well visible in the late evening sky.

Saturn is past opposition but is still bright and a worthwhile telescopic object.

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

# posted by Ian Musgrave @ 5:37 pm 0 comments


Evening sky on Friday, December 22 as seen from Adelaide at 22:16 ACDST (90 minutes after sunset). Asteroid Vesta is at apposition in Orion. The inset is the binocular view of Vesta at this time. At magnitude 6.6 it will be an easy binocular object near clear guide stars. Similar views will be seen elsewhere in Australia at the equivalent local time.	The approximate binocular view of Vesta and the guide stars at on from Thursday, December 23 on. with the track of Vesta shown (click to embiggen, similar views will be seen elsewhere at the equivalent local time).

Black and white horizon chart facing east suitable for printing showing the guide objects of 4 Vesta Elnath, Propus and Chi orionus as seen from Adelaide at 22:16 ACDST. Similar views will be seen elsewhere in Australia at the equivalent local time. Use the charts above to orient yourself to get to the guide stars.	Black and white binocular chart suitable for printing showing the movement of 4 Vesta over December. The large circle represents the field of view of 10x50 binoculars. Click to embiggen and print. Use the horizon chart to the left for orientation first.

The Asteroid 4 Vesta is one of the iconic minor planets, and one of two orbited by the Dawn spacecraft. At favorable oppositions Vesta is bright enough to be seen with the unaided eye under dark sky conditions. This year it gets to magnitude 5.8 just over unaided eye visibility at dark sky sites. Not really visible from suburban skies, but it will be easily visible in binoculars and small telescopes.

This year on Friday, December 22 is a so-so opposition of Vesta, when it will reach a magnitude of 6.4 at its brightest with reasonable guide stars and some Moon interference. The next bright opposition is May 2025 it will reach magnitude 5.6 with good guide stars.

This year Vesta has some reasonable signposts to it, just before and just after opposition Vesta is roughly between the moderately bright star ζ-Tau (Tianguan) and the moderately bright star Propus. In binoculars if you star hop from the bright star Aldebaran to ζ-Tau, the fainter star that represents the tip of the second horn of Taurus (brighter Elnath represents the tip of the other horn, see charts above), then about a binocular width away is the distinctive trio of 𝛘1 Orionis, 57 Orionis and HIP 27747. Vesta is in the same binocular field just under 𝛘1 Orionis. Vesta's movement from night to night easily seen.

Finding Vesta with the charts should be easy. Print them out and use with a red-light torch (or a standard torch with red cellophane over it) so as to not disturb your night vision.

The waxing Moon will interfere later in the month, but now the waxing Moon should allow Vesta to be easily seen.

Labels: 4 Vesta, Asteroid, binocular

# posted by Ian Musgrave @ 8:26 pm 0 comments

The Full Moon is Wednesday, December 27. Earth is at Solstice on the 22nd. Saturn is now in the west when twilight ends. Jupiter is highest around nautical twilight and is now well visible in the evening sky. Jupiter is close to the waxing moon on the 22nd. Venus is visible in the morning twilight.The Asteroid Vesta is at opposition on the 22nd and will be visible in binoculars.

The Full Moon is Wednesday, December 27. Earth is at Solstice, when the day is longest, on December 22.

Evening sky on Saturday, December 23 as seen from Adelaide at 22:17 ACDST (90 minutes after sunset), Saturn is above the western horizon. The inset is the telescopic view of Saturn at this time.

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

Evening sky on Friday, December 22 as seen from Adelaide at 22:16 ACDST (90 minutes after sunset). Jupiter is close to the waxing Moon. The inset is the telescopic view of Jupiter at this time.

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

Evening sky on Friday, December 22 as seen from Adelaide at 22:16 ACDST (90 minutes after sunset). Asteroid Vesta is at apposition in Orion. The inset is the binocular view of Vesta at this time. At magnitude 6.6 it will be an easy binocular object near clear guide stars. More details and charts are at my Vesta page.

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

Morning sky on Saturday, December 23 as seen from Adelaide at 04:53 ACDST, (60 minutes before sunrise, click to embiggen). Venus is beginning to lower in the morning twilight and is heading towards Scorpius. The inset is the telescopic view of Venus at this time.

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

Whole sky on Saturday, December 23 as seen from Adelaide at 22:17 ACDST, 90 minutes after sunset (click to embiggen). Saturn is setting in the north-west, and Jupiter is high in the north.

Sagittarius is almost set. Orion is rising in the east.

Between the bright star Canopus and the Southern Cross are another wealth of binocular objects to discover.

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

Mercury is lost in the twilight.

Venus is high in the morning twilight, it will now sink towards the horizon but will remain easily visible for all of November.

Mars is lost in the twilight.

Jupiter is highest around nautical twilight and is now well visible in the late evening sky.Jupiter is close to the waxing Moon on the 22nd,

Saturn is past opposition but is still bright and a worthwhile telescopic object.

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

# posted by Ian Musgrave @ 12:36 am 0 comments

The First Quarter Moon is Wednesday, December 20. Saturn is highest in the northern evening sky around 6:00 p.m. local time and is close to the waxing Moon on the 17th. Jupiter is rising before astronomical twilight and is now well visible in the evening sky. Venus is visible in the morning twilight. The Geminid meteor shower peaks on the early morning 15th.

The First Quarter Moon is Wednesday, December 20. The Moon is at perigee, when it is closest to the Earth. on the 17th.

Evening sky on Sunday, December 17 as seen from Adelaide at 22:13 ACDST (90 minutes after sunset), Saturn is above the northwestern horizon near the waxing Moon. The inset is the telescopic view of Saturn at this time.

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

Evening sky on Saturday, December 16 as seen from Adelaide at 22:12 ACDST (90 minutes after sunset). Jupiter is past opposition, when it is biggest and brightest as seen from Earth, but is still bright. The inset is the telescopic view of Jupiter at this time.

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

Morning sky on Saturday, December 16 as seen from Adelaide at 04:50 ACDST, (60 minutes before sunrise, click to embiggen). Venus is beginning to lower in the morning twilight and is below Spica. The inset is the telescopic view of Venus at this time.

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

Morning sky on Friday, December 15 as seen from Adelaide at 03:30 ACDST, (when the Geminid radiant is highest, click to embiggen). Visible in the early morning until dawn, this year the peak is on the 14th, with no moon interference. The Geminids are often bright and intensely coloured. Due to their medium-slow velocity, persistent trains are not usually seen. Between a meteor ever 1-2 minutes should be seen under dark skies in northern Australia. A more comprehensive guide with rates for several cities is my Geminid page.

Similar views will be seen from the rest of Australia at the equivalent local time (when the Geminid radiant is highest, click to embiggen).

Whole sky on Saturday, December 16 as seen from Adelaide at 22:12 ACDST, 90 minutes after sunset (click to embiggen). Saturn is setting in the north-west, and Jupiter is rising in the north-east.

Scorpius is almost set and Sagittarius is still visible below the zenith heading towards the western horizon. Orion is rising in the east.

Between the bright star Canopus and the Southern Cross are another wealth of binocular objects to discover.

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

Mercury is lost in the twilight.

Venus is high in the morning twilight, it will now sink towards the horizon but will remain easily visible for all of November.

Mars is lost in the twilight.

Jupiter rises before astronomical twilight and is now well visible in the late evening sky.

Saturn is past opposition but is still bright and a worthwhile telescopic object. Saturn is close to the waxing Moon on the 17th.

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

# posted by Ian Musgrave @ 1:23 am 0 comments


The northern horizon at 3:13 am ACDST as seen from Adelaide on Friday December 15 when the Geminid radiant is at its highest. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at a similar latitude and the equivalent local time. (click to embiggen).	The northern horizon at 2:13am AEST as seen from Brisbane on on Friday December 15 when the Geminid radiant is at its highest. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at a similar latitude and the equivalent local time. (click to embiggen).	The northern horizon at 3:17 am AEDST as seen from Melbourne on Friday December 15 when the Geminid radiant is at its highest. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at a similar latitude and the equivalent local time. (click to embiggen).

This year is a good year for the Geminid meteor shower. The Geminids are unusual meteor shower in that their parent body is 3200 Phaethon, an asteroid, rather than a comet. It is speculated though that Phaeton is actually a "gassed out" comet, and so the debris that makes up the Geminids may still be cometary particles, but is more likely broken rock fragments from its close approach to the sun.

The Geminids are usually a fairly reliable meteor shower and this year promises to be a good one as there will be no interference from the Moon.

The Geminids have a broad peak and normally show good activity well before and after the peak on the day before and after. The nominal peak is December 14, 19h UT, that means in Australia this year most of the activity is concentrated on the morning of the 15th. Yes, it's week day, but it's a Friday, so you can afford to lose a little sleep. As the radiant doesn't rise until just before midnight (daylight saving time) in most of Australia and the radiant is highest (with the best meteor rates) in the early hours you are going to lose some sleep for this.

Northern Australians should see a meteor every 1 to 2 minutes under dark skies in the early morning of the 15th between roughly midnight (14th) and 3:00 am local time (15th). Obviously under suburban skies you will see fewer.

You can find predictions for your local site at the meteor flux estimator (choose 4 Geminids and date 14-15 December, don't forget to change the date to 2023). You will have to enter your local latitude and longitude for your site. I have also made a table for major cities below.

Unfortunately, both Chrome and Firefox have changed their security settings to prevent plugins from running, and the flux estimator only runs under Internet Explorer now OR Edge in Internet Explorer mode (click on the triple dots one the page has loaded ), you have to have the JAVA plugh-in loaded

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You can follow the progress of the shower at the IMO Geminids Live page.

At 1.00 am in the morning AEDST (midnight, AEST) Castor (alpha Geminorum) is about three hand-spans above the horizon and roughly north-east. Pollux, the other twin, is less than a hand-span to the right again. The radiant is just below Pollux. The best rates is when the radiant is highest,when it is due north.

City	Time Radiant Highest
Adelaide	3:13 ACDST
Brisbane	2:13 AEST
Darwin	2:43 ACST
Hobart	2:38 AEDST
Melbourne	3:17 AEDST
Perth	2:13 AWST
Sydney	2:52 AEDST

When you get up, allow at least 5 minutes for your eyes to adjust and become dark adapted (even if you have stumbled out of bed in the dark, here's some hints on dark adaption of your eyes so you can see meteors better).

Be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession (a meteor every 1 to 2 minutes is an average, they won't turn up like a ticking clock but more or less randomly).

Predicted meteor rates for selected towns

Locations on the same latitude as...	Morning December 13	Morning December 14 (UT peak)	Morning December 15 (best)	Morning December 16
Darwin	6 meteors/hr	14 meteors/hr	63 meteors/hr	14 meteors/hr
Brisbane/Perth	8 meteors/hr	16 meteors/hr	45 meteors/hr	11 meteors/hr
Sydney/Adelaide/Canberra	6 meteors/hr	13 meteors/hr	35 meteors/hr	8 meteors/hr
Melbourne	6 meteors/hr	11 meteors/hr	31 meteors/hr	7 meteors/hr
Hobart	5 meteors/hr	10 meteors/hr	30 meteors/hr	6 meteors/hr

Locations at similar latitudes to the towns in the list will have similar rates, the more north you are the higher the rate. Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with street lights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an insalubrious park for example).

While the radiant is where the meteors appear to originate from, most of the meteors will be seen away from the radiant, so don't fixate on the radiant, but keep your eye on a broad swath of sky roughly centered just above the radiant (as the radiant doesn't rise very high, looking exactly at the radiant will mean you miss some higher up).

A lawn chair or something similar will make your observing comfortable (or a picnic rug spread on the ground and a nice pillow), and having a Thermos of hot coffee, tea or chocolate to swig while watching will increase your comfort. Despite it being summer, make sure you have a jumper or something as the night can still get cold. Also, plenty of insect repellent is a good idea.

Guides to taking meteor photos are here and here.

As well, Orion and the Hyades will be visible, with Jupiter setting in the west and Venus rising in the twilight. So it will be a quite nice morning for sky watching. Keep an eye out for satellites! There may be a bright ISS pass on the morning of the 15th from your location.

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: geminids, Meteors, unaided eye

# posted by Ian Musgrave @ 10:09 pm 0 comments

The New Moon is Wednesday, December 13. Saturn is highest in the northern evening sky around 7:00 p.m. local time. Jupiter is rising before astronomical twilight and is now well visible in the evening sky. Venus is visible in the morning twilight and is close to the thin crescent Moon on the 10th. Mercury is visible low in the twilight and is close to the thin crescent moon on the 14th. The Geminid meteor shower begins to peak on the evening 14th-early morning 15th.

The New Moon is Wednesday, December 13.

Evening sky on Thursday, December 14 as seen from Adelaide at 21:15 ACDST (45 minutes after sunset), Mercury is low to the horizon, near the thin crescent moon. the pair may be difficult to see without binoculars.

Similar views will be seen from the rest of Australia at the equivalent local time (450 minutes after sunset).

Evening sky on Saturday, December 9 as seen from Adelaide at 22:06 ACDST (90 minutes after sunset), Saturn is above the northwestern horizon. The inset is the telescopic view of Saturn at this time.

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

Evening sky on Saturday, December 9 as seen from Adelaide at 22:06 ACDST (90 minutes after sunset). Jupiter is past opposition, when it is biggest and brightest as seen from Earth, but is still bright. The inset is the telescopic view of Jupiter at this time.

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

Morning sky on Sunday, December 10 as seen from Adelaide at 04:49 ACDST, (60 minutes before sunrise, click to embiggen). Venus is beginning to lower in the morning twilight and is close to the thin crescent Moon below Spica. The inset is the telescopic view of Venus at this time.

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

Morning sky on Friday, December 15 as seen from Adelaide at 03:30 ACDST, (when the Geminid radiant is highest, click to embiggen). Visible in the early morning until dawn, this year the peak is on the 14th, with no moon interference. The Geminids are often bright and intensely coloured. Due to their medium-slow velocity, persistent trains are not usually seen. Between a meteor ever 1-2 minutes should be seen under dark skies in northern Australia. A more comprehensive guide with rates for several cities is my Geminid page.

Similar views will be seen from the rest of Australia at the equivalent local time (when the Geminid radiant is highest, click to embiggen).

Whole sky on Saturday, December 9 as seen from Adelaide at 22:06 ACDST, 90 minutes after sunset (click to embiggen). Saturn is setting in the north-west, and Jupiter is rising in the north-east.

Scorpius is almost set and Sagittarius is still visible below the zenith heading towards the western horizon. Orion is rising in the east.

Between the bright star Canopus and the Southern Cross are another wealth of binocular objects to discover.

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

Mercury is sinking in the twilight and is close to the thin crescent moon on the 14th.

Venus is high in the morning twilight, it will now sink towards the horizon but will remain easily visible for all of November. Venus is close to the thin crescent Moon on the 10th..

Mars is lost in the twilight.

Jupiter rises before astronomical twilight and is now well visible in the late evening sky.

Saturn is past opposition but is still bright and a worthwhile telescopic object.

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

# posted by Ian Musgrave @ 12:46 am 0 comments