Astroblog

 Evening sky on Thursday, August 19 showing the western sky as seen from Adelaide at 18:25 ACST (45 minutes after sunset). Mercury is close to Mars with Venus above. 

 (similar views will be seen Australia wide at the equivalent local time, 45 minutes after sunset)

The August edition of Southern Skywatch is now up.

 Mercury  returns to the Evening twilight by mid-month and is at its best late this month and early next month. On the 1st Mercury is lost in the twilight. On the 15th Mercury is just over a hand-span above the western horizon an hour after sunset. Mercury moves closer to Mars and the pair are just 0.2 degrees apart, easily fitting into telescope eyepieces, on the 19th. The pair are best seen around 40 minutes after sunset when the sky is a bit darker, but you will need a fairly level, unobstructed horizon as the pair are just a hand-span and a half above the western horizon. Mercury is brighter than Mars at this time. In the last week of August Mercury, Venus and Spica make a nice line in the late evening twilight. On August 28 Mercury is a finger-width from Zavijava (Beta Viginis). By the 30th Mercury is just under a hand-span from the western horizon an hour and a half after sunset, with Venus and Spica above.

Venus is now easily visible in the evening sky from 30 minutes after sunset (I can see it as early as 10 minutes after sunset). Venus dominates the evening twilight leaving Mars and Regulus behind as it comes closer to closer to the bright star Spica. Venus now a distinct "gibbous Moon" shape. On the 11th Venus is close to the thin crescent Moon. The pair (just) fit into the field of view of a 10x50 binoculars. On the 14th Venus is just half a Moon diameter from Zavijava (Beta Viginis). By mid-month at astronomical twilight, we can enjoy the sight the sight of bright Venus low in the west mirroring bright Jupiter in the east. In the last week of August Mercury, Venus and Spica make a nice line in the late evening twilight.

Mars is low above the western horizon, best seen an hour after sunset at the beginning of the month but progressively lowering and by the end of the month it will be difficult to see in the twilight. Mars is close to the crescent Moon on the 10th and the pair fit into a binocular field. From the 17th to the 21st Mars and mercury are close being closest on the 19th at less than 1 lunar diameter apart.

Jupiter is readily visible around 9 pm local time and continues to climb into the late evening sky. On the 19th, Jupiter is at opposition, when it is biggest and brightest as see from Earth. By mid-month at astronomical twilight, we can enjoy the sight the sight of bright Venus low in the west mirroring bright Jupiter in the east. Once Venus has set Jupiter dominates the night sky. On the 21st the waxing Moon is between Saturn and Jupiter. On the 22th the Full Moon is close to Jupiter. Telescopically Jupiter will be best late evening to the early morning when it is highest above the northern horizon.

Saturncan be easily seen from astronomical twilight (an hour and a half after sunset) from the beginning of August. Saturn is at Opposition, when it is biggest and brights as seen from Earth, on the 2nd. On the 20th the nearly full moon forms a line with Saturn and Jupiter. On the 21st the moon is between Jupiter and Saturn. Then on the 23rd the waning moon again forms a line with Jupiter and Saturn. The beginning of the month Saturn should be best for scopes around 11 pm local time (it will be good before then, but it is better when it is highest and in still air). As the month goes on Saturn rises earlier and it and Jupiter are prominent below the teapot of Sagittarius.

Apogee August 2 and 30; Moon at perigee August 17.

Labels: southern skywatch

# posted by Ian Musgrave @ 9:01 pm 0 comments

Evening sky looking east from Adelaide at 11 pm local time in South Australia. The starburst marks the radiant  (the point where the meteors appear to originate from) of the Southern Delta Aquariids. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).	Evening sky looking east from Adelaide at 2:30 am local time on July 30th in South Australia. The starburst marks the radiant  (the point where the meteors appear to originate from) of the Southern Delta Aquariids.  Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

The Southern Delta-Aquarids meteor shower runs from from 12 July to 23rd August, peaking on Friday July the 30th. The number of meteors you will see depends on how high the radiant is above the horizon, and how dark your sky is. This shower is fairly faint, with the highest rate of around a meteor every 4 minutes (more detail below).

The ZHR  for Southern Delta Aquariids is 25 meteors per hour. The figure ZHR is zenithal hourly rate. This is the number of meteors that a single observer would see per hour if the shower's "point of origin", or radiant, were at the zenith and the sky were dark enough for 6.5-magnitude stars to be visible to the naked eye.

In practise, you will never see this many meteors as the radiant will be some distance below the zenith. Also, unless you are out deep in the countryside, the darkness will be less than ideal. As well, moonlight will significantly reduce rates. How many are you likely to see in reality? I discuss this further down, lets talk about when to see them first.

At 11 pm, face east, and look around 4 hand spans above the horizon. Jupiter is obvious as the brightest object above the horizon. The radiant is just above Jupiterr. This meteor shower should be visible from 10.00 pm until dawn. The Moon will significantly interfere this year, being close to the radiant.  The best rates will be at 23:00 pm on the evenings of the 29th and 30th. while the radiant is not at its highest then when he Moon rises the rates will drop significantly.

At 11pm people in the suburbs should see a meteor around once every 12 minutes, and in the country about once every 7 minutes on the evenings of the 29th and 30th.

When looking, be sure to let your eyes adjust for at least 5 minutes so your eyes can be properly adapted to the dark. Don't look directly at the radiant site, because the meteors will often start their "burn" some distance from it, but around a hand-span up or to the side. Be patient, although you should see an average of a meteor every six to four minutes, a whole stretch of time can go by without a meteor, then a whole bunch turn up one after the other.

Make yourself comfortable, choose an observing site that has little to obstruct the eastern horizon, have a comfortable chair to sit in (a banana lounger is best), or blankets and pillows. Rug up against the cold.  A hot Thermos of something to drink and plenty of mosquito protection will complete your observing preparations. As well as meteors, keep an eye out for satellites (see Heavens Above for predictions from your site).

The sky will also be particularly beautiful, with the Milky Way stretching over the sky and constellation of Scorpius, Jupiter and Saturn gracing the western sky.

 Use the NASA  meteor shower flux estimator for an estimate of what the shower will be like from your location. 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. 

Labels: Meteors, unaided eye

# posted by Ian Musgrave @ 10:32 pm 0 comments

The Last Quarter Moon is Saturday, July 31.  This is  a "blue" Last Quarter Moon, the second last quarter Moon in a month. The Moon is at apogee, when it is furthest form the Earth, on August 2nd.

Evening sky on Monday, August 2

Whole sky at 19:01 ACST  (90 minutes after sunset), on Saturday, July 31 as seen from Adelaide. 

Evening twilight sky on Friday, July 30 looking north-west as seen from Adelaide at 18:30 ACST (60

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

 

 

Evening sky looking east from Adelaide at 11 pm local time in South Australia. The starburst marks the radiant  (the point where the meteors appear to originate from) of the Southern Delta Aquariids. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

The Southern Delta-Aquarids meteor shower runs from from 12 July to 23rd August, peaking on Thurday July 29 to 30. The number of meteors you will see depends on how high the radiant is above the horizon, and how dark your sky is. This shower is fairly faint, with the highest rate of around a meteor every 7 minutes. This year the shower occurs when the Moon is close to the radiant so lower rates will be seen than usual.

At 11 pm, face east, and look  towards Jupiter (the brightest object above the eastern horizon). The radiant is just below Jupiter. This meteor shower should be visible from 10.00 pm until dawn. However, after Moon rise the rates will fall off considerably.

Labels: weekly sky

# posted by Ian Musgrave @ 11:11 pm 1 comments

The Full Moon is Saturday, July 24.

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

 

 

Evening sky looking east from Adelaide at 11 pm local time in South Australia. The starburst marks the radiant  (the point where the meteors appear to originate from) of the Southern Delta Aquariids. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

The Southern Delta-Aquarids meteor shower runs from from 12 July to 23rd August, peaking on Thurday July 29 to 30. The number of meteors you will see depends on how high the radiant is above the horizon, and how dark your sky is. This shower is fairly faint, with the highest rate of around a meteor every 7 minutes. This year the shower occurs when the Moon is close to the radiant so lower rates will be seen than usual.

At 11 pm, face east, and look  towards Jupiter (the brightest object above the eastern horizon). The radiant is just below Jupiter. This meteor shower should be visible from 10.00 pm until dawn. However, after Moon rise the rates will fall off considerably.

Labels: weekly sky

# posted by Ian Musgrave @ 1:33 am 0 comments

The First Quarter Moon is Saturday, July 17. The Moon is at Perigee, when it is closest to Earth, on the 21st.

Morning twilight sky at 6:53 ACST (30 minutes before sunrise), on Saturday, July 17 facing east as seen from Adelaide. 

 

Mercury is visible low in the twilight.
 

 

 Similar views will be seen elsewhere in Australia at the equivalent local time  (30 minutes before sunrise)

 

 

 

 

Mercury is now low in the morning twilight this week, this week will be the last opportunity to spot the fleet planet this month.

Venus is visible in the late twilight.  I have been able to see Venus from 15 minutes after sunset and it is easily seen 60 minutes after sunset.  Venus has passed Mars and closes in on the bright star Regulus, being closest on the 22nd.

Mars is visible in the evening sky above the north-western horizon in the early evening. Mars is being left behind by Venus after last weeks close approach.

   
Jupiter is now above the eastern horizon well before midnight. 

 

 Saturn is now rising well around 8pm. 

 
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 @ 6:30 pm 2 comments

Western evening twilight sky on Monday, July 12 looking north-west as seen from Adelaide at 18:20 ACST (60 minutes after sunset). Venus is low above the horizon. Venus is close to Mars and the thin crescent Moon. Similar views will be seen throughout Australia at the equivalent local time (60 minutes after sunset, click to embiggen).	Western evening twilight sky on Tuesday, July 13 looking north-west as seen from Adelaide at 18:20 ACST (60 minutes after sunset). Venus is low above the horizon. Venus is closest to Mars at this time and the pair form a triangle with the Moon and bright star Regulus. Similar views will be seen throughout Australia at the equivalent local time (60 minutes after sunset, click to embiggen).
Approximate binocular view of Venus, Mars and crescent Moon on Monday 60 minutes after sunset  (with higher power binoculars you may need to Juggle a bit to gt Mars and the edge of the Moon)	Approximate view of Venus, and Mars on Monday 60 minutes after sunset simulated in Stellarium for a 12mm eyepiece and 6" Newtonian scope.

The next few days the evening twilight will be graced with a delightful spectacle as the Moon visits the bright planets and a bright star.

On Monday July 12 there is a lineup of Venus, Mars and the thin Crescent Moon. Venus is visible from 10 minutes after sunset above the western horizon, but you will need to wait until an hour after sunset to see Mars clearly. the trio should just fit into the field of view of 1050 binoculars.If you have a level clear horizon like the sea or desert you should be ale to see them up to 90 minutes after sunset when the sky is fully dark (horizon murk permitting).

On Tuesday July 13  Venus, which has been approaching Mars over the past few weeks, is at at its closest to Mars. The pair can be seen together in medium power telescope eyepieces. The pair also form a triangle with the bright star Regulus and the Crescent Moon.

Labels: binocular, Mars, telescope, unaided eye, Venus

# posted by Ian Musgrave @ 3:32 pm 0 comments

The ISS passing through Leo and above Venus and Mars around 19:10, Canon IXUS 1 seconds exposure, 20 images. Images stacked in ImageJ and a MAX-Z projection with brightness turned up.	Same sequence. Images stacked in Deep sky stacker and aligned on the stars then curves adjusted in GIMP. Click to embiggen.

This evening was excellent for the ISS pass.Clear and cloudless, the ISS passed through Leo above Regulus, Mars and Venus, a rather spectacular pass. Having Learn my lesson from the previous nightI went with  a train of 10 1 second exposures at ISO 1600. I captured most of the pass, with a gap due to timer delay i setting off the 10 shot train.

I stacked the images first in image J, aligned on the frames. The earth rotated in the 30 seconds the sequence took, so the stars and planets are trailed. Then I stacked in DeepSkyStacker aligned on the stars for comparison, the stars aren't trailed but the horizon is blurred and DeepSkyStacker dropped a few frames. Of course, with the camera chugging away by it self I could watch the pass which was rather nice indeed.

Animated GIF of the ISS under the Southern Cross

Labels: astrophotography, ISS, Satellite

# posted by Ian Musgrave @ 2:11 am 0 comments

The ISS passing under the Southern Cross around 18:20, Canon IXUS 2 seconds exposure, 10 images, but for some reason this new IXUS version defaults to ISO 80 on long exposures. Images stacked in ImageJ and a MAX-Z projection with brightness waaayy up.	he ISS passing near Scorpius around 18:20, and disappearing into a cloud bank. Canon IXUS 1 second exposure, 1SO 800. Images stacked in ImageJ and a MAX-Z projection with brightness maxed again. Click to embiggen.

Cloud scotched and idea of imaging Venus and Mars, but were patchy enough to get some shots of the magnitude -3.4 pass of the ISS. I used the custom 10 sequential shots option of my Canon IXUS (on tripod with 10 second delay). The first shot I used long exposure, but this new IXUS version defaults to ISO 80 on long exposures and is kind of rubbish. 

When the first sequence went off I tried to switch over to programed imaging, ISO 800, max1 second exposure, but becuase I was all thumbs by the time I had set everything up the ISS had passed through the scorpions tail and into a cloud bank.

Despite the imaging misadventures I got to see the entire thing and it was wonderful.

Animated GIF of the ISS under the Southern Cross

# posted by Ian Musgrave @ 9:08 pm 0 comments

The ISS as seen from Melbourne  on the evening of  Friday 9 July at 18:40 AEST. Simulated in Stellarium (the ISS will actually be a bright dot), the white line is the path of the ISS, the other lines are paths of other satellites. Click to embiggen.	The ISS  as seen from Adelaide on the evening of  Thursday 8 July at 18:43 ACST. Simulated in Stellarium (the ISS will actually be a bright dot), the white line is the path of the ISS, the other lines are paths of other satellites. Click to embiggen.	The ISS as seen from Perth on the evening of  Thursday 8 July at 17:38 AWST. Simulated in Stellarium (the ISS will actually be a bright dot), the white line is the path of the ISS, the other lines are paths of other satellites. Click to embiggen.
All sky chart showing local times from Heavens Above for Friday 9 July for Melbourne.	All sky chart showing local  times from Heavens Above for Thursday 8 July for Adelaide.	All sky chart showing local times from Heavens Above for  Thursday 8 July for Perth.

Passes from Hobart (AEST) 

Passes from Melbourne (AEST)

Passes from Perth (AWST)

Passes from Sydney (AEST)

When and what you will see is VERY location dependent, so you need to use  Heavens Above  to get site specific predictions for your location, a small difference in location can mean the difference between the ISS passing over a star or planet or missing it completely. 

As always, start looking several minutes before the pass is going to start to get yourself oriented and your eyes dark adapted. Be patient, there may be slight differences in the time of the ISS appearing due to orbit changes not picked up by the predictions. Use the most recent prediction for your site.

Labels: ISS, Satellite, unaided eye

# posted by Ian Musgrave @ 1:55 pm 0 comments