Astroblog: December 2024

Tuesday, December 10, 2024

Thursday December 12 to Thursday December 19

The Full Moon is Sunday December 15. In the evening Venus is coming closer to Saturn. Jupiter , Saturn and Venus are visible in the evening sky. Jupiter is at opposition and is visible all night long. Jupiter is close to the nearly full Moon on the 14th. In the morning Mars and Jupiter continue to draw apart. Mars is close to the Moon on the 18th and 19th. The Geminid meteor shower peaks on the morning of the 14th, but moonlight interferes.

The Full Moon is Sunday December 15.

Western evening sky on Saturday, December 14 as seen from Adelaide at 21:31 ACDST (60 minutes after sunset, click to embiggen).

Venus is readily visible from early twilight to when the sky is fully dark. Venus is coming closer to Saturn.

The insets are the telescopic views of Venus and Saturn at this time.

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

North-eastern evening sky on Saturday, December 14 as seen from Adelaide at 22:12 ACDST (90 minutes after sunset), Jupiter is rising in the north-east and is close to the Moon.

The inset is the telescope view of the Jupiter at this time (Io is eclipsed by Jupiter). (click to embiggen).

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

North-eastern sky on Wednesday, December 18 as seen from Adelaide at midnight ACDST, Mars is rising just above the waning Moon

Similar views will be seen from the rest of Australia at roughly the equivalent local time.

Northern morning sky on Saturday, December 14 as seen from Adelaide at 03:13 ACDST, when the Geminid meter shower is at it's highest.

Mars and Jupiter form a line with the red star Aldebaran. the Geminid meteor shower radiant is approximately between them and is marked with a star burst.

More detailed viewing instructions are at my Geminid viewing page.

Similar views will be seen from the rest of Australia at roughly the equivalent local time, exact timings at my Geminid viewing page.

Whole sky on Saturday, December 14 as seen from Adelaide at 22:12 ACDST, 90 minutes after sunset (click to embiggen).

Jupiter is rising in the east Saturn is now above the north-western horizon and coming closer to Venus. Orion the hunter is rising in the east. The Southern Cross is low in the Southern sky. The moon is nearly full and the fainter clusters and nebula are hard to see.

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

Mercury is lost in the twilight.

Venus climbs higher in the evening twilight and is readily visible in the evening twilight. Venus is coming closer to Saturn.

Mars is rising in the morning sky and near Jupiter. The pair continue to draw apart. Mars is close to the Moon on the 18th and 19th.

Jupiter is rising in the the evening sky when the sky is fully dark and is at opposition, when it is biggest and brightest as seen from Earth. Jupiter is close to the nearly full Moon on the 14th.

Saturn is lowering in the evening sky coming closer to Venus.

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 @ 8:42 am 0 comments

Monday, December 09, 2024

Geminid Meteor Shower 13-15 December 2024


The northern horizon at 3:13 am ACDST as seen from Adelaide on Saturday December 14 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 1:46am AEST as seen from Brisbane on on Saturday December 14 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 Saturday December 14 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 poor year for the Geminid meteor shower. The Geminids are an 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 but this year there will be significant 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, 01h UT, that means in Australia this year most of the activity is concentrated on the morning of the 14th after sunrise, but there will still be decent rates before twilight (although lower this year because of the moonlight).

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 in a narrow band around 3 am local time, so you are going to lose some sleep for this. Fortunately this is a Saturday, so you can sleep in after.

Northern Australians should see a meteor every 1 to 2 minutes under dark skies in the early morning of the 14th. 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 13-14 December, don't forget to change the date to 2024). 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 once the page has loaded ), you have to have the JAVA plug-in loaded.

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

At 3.00 am in the morning AEDST (midnight, AEST) Castor (alpha Geminorum) is about four hand-spans above the horizon and almost due north. Pollux, the other twin, is less than a hand-span to the right again and below Castor. The radiant is just below Pollux. The best rates are when the radiant is highest, when it is due north, the Moon is low to the horizon and before astronomical twilight. This is around 3:30 am ACDST Adelaide ~4:00 ACST Darwin, ~3-3:30 am local time Perth and Brisbane and ~ 3:30-4:00 am AEDST Melbourne, Sydney and Hobart.

City	Time Radiant Highest	Moon set	Astronomical Twilight
Adelaide ACDST	3:13	4:18	4:09
Brisbane AEST	1:46	3:08	3:14
Darwin ACST	2:43	4:43	4:57
Hobart AEDST	2:38	3:16	2:39
Melbourne AEDST	3:17	4:14	4:00
Perth AWST	2:13	3:31	3:25
Sydney AEDST	2:52	4:00	3:56

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	Morning December 16
Darwin	19 meteors/hr	48 meteors/hr	11 meteors/hr	2 meteors/hr
Brisbane/Perth	13 meteors/hr	37 meteors/hr	10 meteors/hr	2 meteors/hr
Sydney/Adelaide/Canberra	10 meteors/hr	27 meteors/hr	7 meteors/hr	2 meteors/hr
Melbourne	9 meteors/hr	22 meteors/hr	7 meteors/hr	2 meteors/hr
Hobart	7 meteors/hr	17 meteors/hr	6 meteors/hr	2 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. Try and choose a spot where the moon is hidden from view to preserve your night vision.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 in the Hyades and Mars Not far from Castor and Pollux. . 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 @ 9:59 pm 1 comments

Tuesday, December 03, 2024

Thursday December 5 to Thursday December 12

The First Quarter Moon is Monday December 8. There is an opportunity to see the Lunar X in daytime. In the evening Venus leaves Sagittarius behind and is coming closer to Saturn. Saturn is close to the first quarter Moon and there is a daytime occultation of Saturn as seen from Darwin. Jupiter is now visible in the evening sky along with Saturn and Venus and is at opposition on the 8th. In the morning Mars and Jupiter continue to draw apart. Mars remains within a binocular distance of the Beehive cluster.

The First Quarter Moon is Monday December 8. The Moon is at perigee, when it is closest to the Earth, on the 12th.

Western evening sky on Saturday, December 8 as seen from Adelaide at 21:23 ACDST (60 minutes after sunset, click to embiggen).

Venus is readily visible for early twilight to when the sky is fully dark. Venus is leaving Sagittarius behind and is coming closer to Saturn, with the Moon between them.

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 after sunset).

The eastern sky at 17:17 ACST Sunday, December 8 as seen from Darwin .

Saturn is about to be occulted by the Moon. The inset shows the telescopic view of Saturn and the this time. (click to embiggen).

The other inset shows the Lunar X as seen at 0236 UT (14:36 AEDST, 13:36 AEST, 14:06 AEDST, 1306 ACST the Moon is on the horizon in WA)

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

Eastern evening sky on Saturday, December 7 as seen from Adelaide at 22:06 ACDST (90 minutes after sunset), Jupiter is rising in the east. Jupiter comes to opposition, when it is biggest and brightest as seen fom Earth, on the 8th.

The inset is the telescope view of the Jupiter at this time (Io is eclipsed by Jupiter). (click to embiggen).

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

Northern morning sky on Saturday, December 7 as seen from Adelaide at 04:49 ACDST (60 minutes before sunrise), Mars and Jupiter form a line with the red star Aldebaran. Mars is within binocular range of the iconic Beehive cluster. The inset is the binocular view at this time.

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

Whole sky on Saturday, December 7 as seen from Adelaide at 21:57 ACDST, 90 minutes after sunset (click to embiggen).

Jupiter is rising in the east. Saturn is now above the north-western horizon and coming closer to Venus. as the tail of Scorpius disappears in the west. Orion the hunter is rising in the east. The Southern Cross is low 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 is lost in the twilight.

Venus climbs higher in the evening twilight and is readily visible in the evening twilight. Venus leaves Sagittarius behind and is coming closer to Saturn. On the 6th and 7th the waxing Moon is between Venus and Saturn.

Mars is rising in the morning sky and near Jupiter. The pair continue to draw apart as as Mars passes into Cancer. Mars is within binocular distance of the beehive on from December 8-14.

Jupiter is rising in the the evening sky when the sky is fully dark but is best in the morning. Jupiter is below the red star Aldebaran forming a line with Mars.

Saturn is lowering in the evening sky coming closer to Venus. Saturn is visible all night long. The Moon is close to Saturn on the 8th and there is a daytime ocultation seen from Darwin.