Astroblog

The Last Quarter Moon is Monday March 4. Jupiter is low in the north-western sky but still dominates the early evening sky. Venus is visible in the morning twilight below Mars. Mars  continues to climb away from Venus as the week progresses.

The Last Quarter Moon is Monday March 4.

Whole sky on Saturday, March 2 as seen from Adelaide at 21:18 ACDST, 90 minutes after sunset (click to embiggen). Jupiter is low in the north-west.

Orion is almost due north. Bright Sirius is high in  the eastern sky. Between the bright star Canopus and the Southern Cross are a 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 in the morning twilight, it is sinking towards the horizon but will remain visible for all of March. Mars and Venus draw further apart.

Mars is rising in the morning twilight and moving away from Venus. 

Jupiter is visible low in the early evening sky.

Saturn is lost in the twilight.

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 @ 10:26 pm 0 comments

I don’t know about you folks, but the feed in the social media formerly known as twitter is currently dominated by “cute poop” ads (who seem to have displaced the chemtrailers) and flat earthers. 

The former is a mildly puzzling Japanese phenomenon, while the latter appears to be dominated by people who have not progressed past a pre-Babylonian view of the world, but who possess P1000 cameras they don’t know how to focus. 

Now as a long-time viewer of the the skies and their wonders, these folks give me the screaming irrits, but I take this as a chance for a teachable moment, and get people involved in measuring the distance to the Moon in a way that anyone can undertake. One of the tenets of the flat earth movement is that the sun and moon are both small and local (that sound you are hearing is the ghost of Aristarchus howling at the said Luna). 

 Now, Aristarchus used the time it took for earth's shadow to cross the Moon in a lunar eclipse and got a figure that was 1/3 the modern distance, not bad for unaided eye observation without modern clocks (and thousands of times further than the flat earth requirement of “local”). 

Now there are no convent total lunar eclipses this year, so we can’t reproduce Aristarchus’s methods. 

The most common method for determining the distance to the moon, if you are not bouncing lasers off the mirrors left by the Apollo Astronauts or Soviets, is parallax. For parallax you and a mate a couple of hundred kilometers away have to take an image of the Moon at the same Universal Time, close to one or more bright stars, with equipment that gives an image of roughly the same scale. And you both need clear skies. Then all you have to do is measure the distance between the stars and the moon, do a bit of maths and viola, you have the distance to the Moon. 

Probably the next best time for parallax is May 23, when the Moon is close to delta Scorpii. Of course, all this requires a bit of organisation, as does most of the demonstrations of the sphericity of earth. 

Fortunately, this is a way to determine the distance to the Moon that one can do just by themselves. All you need is a digital camera with a decent optical zoom function (or attached to a telescope), an accurate timestamp function, a clear horizon, and the patience to take images for most for the night, and an image analysis program like AstroimageJ to measure the Moons diameter https://www.astro.louisville.edu/software/astroimagej/index.html  or a Python script.

All you have to do is measure the radius of the Moon as it rises and the radius of the Moon when it is highest, as well as an accurate measurement of the time the images were taken apply a bit of maths with the radius of the Moon and hey presto, the distance to the Moon! (full details in “The simplest method to measure the geocentric lunar distance: a case of citizen science” at https://arxiv.org/ftp/arxiv/papers/1405/1405.4580.pdf)

Well, of course it’s not that simple. Close to the horizon atmospheric distortion “squashes” the image messing with the accurate measurement of the radius (this is not the horizon illusion, where the Moon appears bigger, when, in fact it isn’t), also, it needs to be a full moon far from apogee or perigee, when there will be enough change in the Moons diameter as it reaches the furthest and nearest points in its orbit to mess up the calculation. 

The Full Moon of February 24th is such a Moon, and this is my challenge: to take images of the Moon between moon rise and the Moon at zenith, then measure their diameter (making sure the images a re time stamped in some way, usually file creation data in the image header will suffice, just make sure you cameras clock is set correctly). 

(Figure 5. Best fit of the measured apparent sizes (error-bars) to the theoretical model (continuous line. The shaded region
correspond to solutions statistically compatible with the observed apparent sizes at a 5% confidence level, from https://arxiv.org/ftp/arxiv/papers/1405/1405.4580.pdf .used with permission).

Of course then you have to run the Python scripts given in “The simplest method to measure the geocentric lunar distance: a case of citizen science” (at https://arxiv.org/ftp/arxiv/papers/1405/1405.4580.pdf. I did mention you needed python didn’t I? sadly, the links in that paper no longer work, but Jorge Zuluaga has kindly passed the scripts on to me so I can send them on.  This link takes you to the Zip file with the Python Scripts. https://drive.google.com/drive/folders/1FXCgbYINt3hBBSU3gPzaY13MgSNIbtL1?usp=sharing

You also need more than two Moon shots for the statistical analysis (see the figures and the linked paper). So, what do you think? Are you up for the challenge?

Labels: astrophotography, citizen science, Moon

# posted by Ian Musgrave @ 10:03 pm 1 comments

The Full Moon Moon is Saturday February 24. This is an apogee (or mini) Moon. Jupiter is low in the north-western sky but still dominates the early evening sky. Venus is visible in the morning twilight near Mars. Mars  begins to climb away from Venus as the week progresses.

The Full Moon Moon is Saturday February 24.  This is an apogee (or mini) Moon, with apogee on the 26th.

 

Whole sky on Saturday, February 24 as seen from Adelaide at 21:29 ACDST, 90 minutes after sunset (click to embiggen). Jupiter is low in the north-west.

Orion is almost due north. Bright Sirius is high in  the eastern sky. Between the bright star Canopus and the Southern Cross are a wealth of binocular objects to discover.The full Moon will make them hard to see though.

 

   

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

 

 

Mercury is lost in the twilight.

Venus is in the morning twilight, it will now sink towards the horizon but will remain visible for all of February. Mars and Venus are close but draw apart.

Mars is rising in the morning twilight and moving away from Venus. 

Jupiter is highest around civil twilight and is now visible low in the early evening sky.

Saturn is lost in the twilight.

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 @ 12:00 am 0 comments

Black and white printable Spotters map for the Nova in Scorpius, at 5:14 ACDST (90 minutes before sunrise). Similar views will be seen in the rest of Australia at 90 minutes before sunrise. The Nova is in the "sting" of Scorpius, close to Lambda Sco. Click to embiggen and print.	Black and white printable binocular map for the Nova in Scorpius, use the spotter map to locate the general area then use this map for detailed location. The Nova is in the "sting" of Scorpius, close to l Scorpii and u Scorpii. Click to embiggen and print.

A bright Nova has been reported in Scorpius.PNV J17261813-3809354 was discovered by Andrew Pearce (Nedlands, W. Australia) on 2024 Feb. 09.8438 UT. It has been confirmed spectroscopically as a classical galactic nova. The nova is currently magnitude 6.4, just below unaided eye visibility, but easily seen in binoculars, see http://www.cbat.eps.harvard.edu/unconf/followups/J17261813-3809354.html for the details. You can get printable magnitude comparison charts at the AAVSO Variable Star Plotter https://app.aavso.org/vsp/

You will have to get up early in the morning to see it though. It doesn't rise until 1 am. 

Labels: nova

# posted by Ian Musgrave @ 12:37 am 0 comments

The First Quarter Moon is Saturday February 17. Saturn is lost to view. Jupiter is now in the north-western sky but still dominates the early evening sky. Jupiter is near the Moon on the 15th. Venus is visible in the morning twilight above Mars. Mars climbs higher in the morning twilight closing in on Venus.

The First Quarter Moon is Saturday February 17. Maximum Libration is on the 19th.

Mercury is lost in the twilight.

 

Whole sky on Saturday, February 17 as seen from Adelaide at 21:39 ACDST, 90 minutes after sunset (click to embiggen). Jupiter is low in the north-west.

Orion is almost due north. Bright Sirius is high in  the eastern sky. Between the bright star Canopus and the Southern Cross are a wealth of binocular objects to discover.The waxing Moon will make them progressively harder to see though.

 

   

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

 

 

Mercury is lost in the twilight.

Venus is in the morning twilight, it will now sink towards the horizon but will remain visible for all of February. Mars and Venus are spectacularly close on the 22nd.

Mars is rising in the morning twilight and is coming closer to Venus.  The pair re spectacularly close on the 22nd.

Jupiter is highest around civil twilight and is now visible low in the early evening sky. Jupiter is near the Moon on the 15th.

Saturn is lost in the twilight.

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 @ 11:11 pm 1 comments

ISS and Tiangong as seen from Adelaide on the evening of Friday 9 February at 21:07 ACDST. Simulated in Stellarium (the ISS will actually be a bright dot). Click to embiggen.	ISS and Tiangong as seen from Sydney on the evening of Friday 9 February at 21:37 AEDST. Simulated in Stellarium (the ISS will actually be a bright dot). Click to embiggen.	ISS and Tiangong as seen from Hobart on the evening of Friday 9 February at 21:37 AEDST. Simulated in Stellarium (the ISS will actually be a bright dot). Click to embiggen.
All sky chart showing local times from Heavens Above for Friday 9 February for Adelaide.	All sky chart showing local times from Heavens Above for Friday 9 February for Sydney.	All sky chart showing local times from Heavens Above for Friday 9 February for Hobart.

Tonight (Friday 9 February) most of Australia will see bright asses of the ISS and the Tiangong space station. Most are concurrent, but for Adelaide, Sydney and Hobart the occur at the same time (see above). There are too many passes for me to do all of Australia, so go to Heavens Above and look at the dedicated pass times for your site.  

Adelaide: 

ISS

Tiangong

Sydney:

ISS

Tiangong

Hobart:

ISS

Tiangong

Labels: ISS, Satellite, tiangong, unaided eye

# posted by Ian Musgrave @ 8:03 am 0 comments

Labels: Henge

# posted by Ian Musgrave @ 3:56 pm 0 comments

The New Moon is Saturday February 10. Saturn is low in the western twilight and is close to the thin crescent Moon on the 11th. Jupiter is now in the north-western sky but still dominates the early evening sky. Jupiter is near the Moon on the 15th. Venus is visible in the morning twilight above Mars and Mercury. Mars climbs higher in the morning twilight closing in on Venus.

The New Moon is Saturday February 10. The Moon is at perigee, when it is closes to the earth, on the 11th. 

The inset is the approximate binocular view at this time.

 

Whole sky on Saturday, February 10 as seen from Adelaide at 21:49 ACDST, 90 minutes after sunset (click to embiggen). Saturn has set, and Jupiter is low in the north-west.

Orion is almost due north. Bright Sirius is high in  the eastern sky. Between the bright star Canopus and the Southern Cross are a wealth of binocular objects to discover.

 

   

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

 

 

Mercury is low in the morning twilight. It is heading towards the horizon.

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

Mars is rising in the morning twilight and is coming closer to Venus. 

Jupiter is highest around civil twilight and is now visible low in the early evening sky. Jupiter is near the Moon on the 15th

Saturn is now a difficult to see low in the west and is close to the thin crescent Moon on the 11th.

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 @ 12:25 am 0 comments

Tiangong as seen from Melbourne  on the evening of  Thursday 1 February at 21:44 AEDST. Simulated in Stellarium (the ISS will actually be a bright dot). Click to embiggen.	Tiangong  as seen from Adelaide on the evening of  Thursday 1 February at 21:12 ACDST. Simulated in Stellarium (the ISS will actually be a bright dot). Click to embiggen.	Tiangong as seen from Perth on the evening of  Thursday 1 February at 20:14 AWST. Simulated in Stellarium (the ISS will actually be a bright dot). Click to embiggen.
All sky chart showing local times from Heavens Above for Thursday 1 February for Melbourne.	All sky chart showing local  times from Heavens Above for Thursday 1 February for Adelaide.	All sky chart showing local times from Heavens Above for Thursday 1 February for Perth.

Relatively bright passes of the Chinese space station Tiangong visible in the evening from Australia aren't that common. Over the next few days there are a series of  bright Tiangong passes in the late evening twilight/early evening and the early morning. Tiangong passes close to Jupiter and several bright stars.Jupiter is a handy orientation point for many passes.

 
The following tables are from data provided from Heavens Above. Particularly impressive passes are highlighted in yellow, passes entering the shadow in blue.
   

Passes from Adelaide (ACDST)

Passes from Brisbane (AEST) 

Passes from Darwin (ACST) 

none in this time frame

Passes from Hobart (AEDST)  
 

Passes from Melbourne (AEDST)

Passes from Perth (AWST) 

Passes from Sydney (AEDST) 

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 Tiangong 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 Tiangong appearing due to orbit changes not picked up by the predictions. Use the most recent prediction for your site.

Labels: Satellite, tiangong, unaided eye

# posted by Ian Musgrave @ 7:31 am 0 comments