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Tuesday, September 29, 2020

 

Thursday October 1 to Thursday October 7

The Full Moon is Friday October 2. Daylight savings starts October 4. The bright planets Venus and Mars are visible in the early morning skies. Venus is below the bright star Procyon and is at its closest to the bright star Regulus. Four bright planets are (just) visible in evening sky. While brightening Mars is rising well before midnight, Jupiter and Saturn still dominate the evening sky. On the 3rd the Moon is near Mars. On the 7th Mars is at it closest to Earth ahead of opposition. Mercury is high in the evening twilight.

The Full Moon is Friday October 2. The Moon is at apogee, when it is furthest from the Earth on the 4th.

Evening sky at 19:19 ACST (60 minutes after sunset) on Saturday, October 3 facing west as seen from Adelaide. Mercury is easily seen above the Western horizon in the late twilight. Mercury is high in the evening twilight.


 

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

 

Whole sky at 19:46 ACST  (90 minutes after sunset), on Saturday, October 3 as seen from Adelaide.

Four bright planets are visible stretching west to east. Mercury Jupiter, Saturn and Mars.  The Moon is jus below Mars. The insets show the telescopic views of Jupiter and Saturn at the same magnification at this time. 

 Similar views will be seen elsewhere at the equivalent local time (90 minutes after sunset). click to embiggen.

Evening sky at 21:00 ACST  on  Saturday, October 3 facing east as seen from Adelaide. Mars is above the eastern horizon just above the Moon. The variable start Mira is visible to the unaided eye now, should be at its predicted maximum brightness.


The inset shows the telescopic view of Mars at this time.


Similar views will be seen elsewhere in Australia at the equivalent local time, click to embiggen.

Morning sky on Saturday, October 3 showing the north-eastern sky as seen from Adelaide at 4:56 am ACST (60 minutes before sunrise). Venus is at it's closest to the bright star Regulus in Leo. The pair will be practically on top of each other.

The top inset is the binocular view of Venus and Regulus. The lower inset is the telescopic view of Venus at this time.
 
Similar views will be seen elsewhere in Australia at the equivalent local time (60 minutes before sunrise), click to embiggen.


This week four bright planets, Mercury , Jupiter, Saturn and Mars can bee (just seen at astronomical twilight, 90 minutes after sunset. Mercury and Mars will be low on the horizon.

Mercury climbs higher in the evening twilight and is at its highest this week, it will sink towards the horizon in the coming weeks.

Venus is below the bright star Procyon and is coming closer to the bright star Regulus. Venus is at it's closest to the bright star Regulus in Leo on the 3rd. The pair will be practically on top of each other.

 Mars is visible in the morning sky to the north, It is now readily visible in the late evening sky but is still best after midnight. Mars is close to the brightening variable star Mira.Mars is close to the Moon on the 3rd.
  
Jupiter can be readily seen in the early evening sky. Jupiter and Saturn stay around a hand-span apart during the week and the pair dominate the evening skies. Jupiter was at opposition, when it was biggest and brightest as seen from Earth, on July the 14th, but is still an excellent sight.
 
Saturn is too is now visible in the early evening skies. Saturn was at opposition, when it was biggest and brightest as seen from Earth, on July the 21st, but is still an excellent sight. 
 
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/



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Saturday, September 26, 2020

 

Catching Mercury's Tail

Mercury has a tail! And late September and early October will be the best times for amateurs to try and image it. Before going into details, a bit of background (this is an extended version of the tangent I did for the astrophiz podcast, the mercury tail talk starts around 17:11)

Images of Mercury with a tail as seen in the STEREO spacecraft H1b imager. The left image  is Mercury as seen in the H1a imager on January 16 of 2010.

For contrast I've put the image from the H1b imager of 8 April to the right. The tail in the H1a imager is better on the 17th, but I've shown the 16th because of a rather unusual circumstance. 
 
On the 16th an asteroid passes behind Mercury, so you get a tail and an asteroidal occultation in the same picture. The tail (it points to the left in the left image, and right in the right image, the vertical bar is an imager artefact). The asteroid is 88 Thisbe.
 
 
 
I should point out that I am a STEREOHUNTER, someone who hunts for comets in images from the stereo spacecraft, although I have been inactive for some years. 

Back in 2008 famed STEROHUNTER Comet Al and I were trying to confirm a comet position in images from STEREO A. I pointed out the nice bright comet moving across the STEREO image field and Comet Al said, "That's not a comet, that's Mercury!". We exchanged the internet equivalent of startled looks. 

The feeling on the Stereohunter list was that it was an artifact, but I remembered an article on sodium emission from Mercury, and went to track down the group and ask them what they thought our tail might be. 

mercury with tailThis is an image of Mercury's tail obtained from combining a full day of data from a camera aboard the STEREO-A spacecraft. The reflected sunlight off the planet's surface results in a type of over-exposure that causes Mercury to appear much larger than its actual size. The tail-like structure extending anti-sunward from the planet is visible over several days and spans an angular size exceeding that of a full Moon in the night sky.(Credit: Image courtesy of Boston University’s Center for Space Physics)

So began a saga that cumulated in the paper "Observations of Mercury’s Escaping Sodium Atmosphere by the STEREO Spacecraft" by Carl Schmidt, Jeffrey Baumgardner, Michael Mendillo, Christopher Davis and Ian Musgrave being read at the European Planetary Science Congress. This paper was the subject of a press release, and has spread wide into the internet (Science Daily, Space.com, and SpaceInfo are just a few examples). It is my first and only scientific paper on astronomy (as very minor co-author of course).

The intense heat of the Sun blasts sodium ions from Mercury’s surface into space. We can see this tail of sodium atoms as glow as they are ionized by the Sun’s UV light. The Moon also as a tail of sodium atoms streaming away from it. 

So why bring it up now? In the wake of Karl Battams magnificent video of Comet C/1999 Y4 (Atlas) as it passed through the STEREO H1 field of view, also featuring Mercury’s sodium tail the question arose, can Mercury’s sodium tail be picked up by amateur astronomers? 

Mercury’s tail has been picked up from Earth by specialized astronomical telescopes with special filters. But what about amateurs? It turns out that they can. There have been several images of Mercury taken by amateurs with fairly modest telescopes and narrow band filters (see here for example). Narrow band filers are widely available (but somewhat pricey) a recent successful imaging used a 589.3/1.0 nm filer, sodium atoms need 589.0/589.6 nm light to glow. 

Image from Qiсһеng Ζһаng. Mercury and its sodium tail on June 4 through a 60 mm refractor and a 589.3/1.0 nm band-pass filter. The trailed star to the lower left is HIP 31650 (it's Qicheng's image, so play nice).

But you will need a guided telescope and integrate a number of exposures (eg 100x 10 second exposures). Could you pick the tail up with simple broadband exposure rather than a narrow-band filter? That is a good question and maybe you could try if you have a guided telescope. 

Evening sky at 19:45 ACST (90 minutes after sunset) on Friday, October 2 facing west as seen from Adelaide. At this time Mercury is at it's furthest elongation from the Sun. Mercury is easily seen above the Western horizon at astronomical twilight.  

In September and October Mercury will be relatively high and good for trying. Mercury’s sodium tail is brightest at perihelion and aphelion. Aphelion is on September 19, but Mercury is only 4 degrees above the horizon at astronomical twilight, when the sky is full dark at the time. 

Mercury is 7 degrees above the horizon at astronomical twilight between the 24th to 29th of September, which is better, but the tail will be fading. 

While fading, this will be an excellent challenge for the telescope owners. 

If you want to read more, there are some excellent academic papers here and here (hat tip to Daniel Fischer for the links)

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Friday, September 25, 2020

 

Tomorrow is International Observe the Moon Night! (Saturday September 26, 2020)

The Moon as seen  from Adelaide looking Northwest at 19:40 ACST, (astronomical twilight, 90 minutes after sunset) similar views will be seen for other parts of Australia at the equivalent local time (90 minutes after sunset) . Click to embiggen. The Moon forms a line with Jupiter and Saturn.

The insets show the telescopic views of  Jupiter and Saturn at this time.

Saturday 26 Sptember is  International Observe the Moon Night. An international initiative to get people out and observe our beautiful nearest neighbour. You don't need much, just your unaided eyes, but even binoculars or a small telescope will greatly aid your appreciation of our Moon.

This weekend the Moon is three days past first quarter and above the North-west horizon forming a line with the planets Saturn and Jupiter. It also forms another line with the bright stars Altair and Vega. All in all a loverly sight.

While not quite as good as Last Quarter, it is a good phase as the terminator, the light dark boundary on the Moons surface, is close to may interesting craters that are at their best at this sun angle. 


A telescopic simulation of the appearance of the Moon at 19:40 ACST, (astronomical twilight, 90 minutes after sunset), several prominent craters are visible, particularly prominent are the Clavius and Logmontanus at the south pole (near the Moon label) and Copernicus (two thirds of the way to the north/bottom). The prominent dark areas, the Sea of Tranquility, the sea of serenity and the sea of showers (which form the eyes and chin of  "the man in the Moon" are easily seen with the unaided eye.  Click to embiggen.

Even with modest binocular craters can be seen along the Moons terminator. A small telescope reveals a wealth of detail, and finding and focusing on the Moon is so much easier than any other class of astronomical object. You can use this map to identify the features you see (the map is upside down from our perspective). This interactive map will help you explore more.

You may wish to try some astrophotography with a mobile phone or a point and shoot camera. Follow the links for hints on imaging the Moon (and also Jupiter) with these systems.

Even if you don't have a telescope, just go out and look the the north-west, the view will be lovely. Around 19:40 you may even see a satellite or two pass over. Including a relatively bright Hubble Space Station pass.

If you don't have a telescope, a local astronomical club may be having an  International Observe the Moon Night near you. Check out this map for locations.

So if the sky is clear, go out and have a look!

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/

 

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Monday, September 21, 2020

 

Thursday September 24 to Thursday October 1

The First Quarter Moon is Thursday September 24. The bright planets Venus and Mars are visible in the early morning skies. Venus is below the bright star Procyon and is close to the bright star Regulus. While brightening Mars is rising well before midnight, Jupiter and Saturn still dominate the evening sky. On the 24th the Moon forms a line with Jupiter and Saturn.On the 25th the Moon forms a triangle with Jupiter and Saturn. On the 26th the line is Jupiter, Saturn and Moon. Mercury climbs above the bright star Spica in the evening twilight. 


The First Quarter Moon is Thursday September 24.

Evening sky at 19:09 ACST (60 minutes after sunset) on Saturday, September 25 facing west as seen from Adelaide. Mercury is easily seen above the Western horizon in the late twilight. Mercury is above the bright star Spica.


 

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

 

Whole sky at 19:39 ACST  (90 minutes after sunset), on Friday September 25 as seen from Adelaide.

Three bright planets are visible stretching west to east. Jupiter, Saturn and Mars.  The Moon forms a triangle with Jupiter and Saturn. The insets show the telescopic views of Jupiter and Saturn at the same magnification at this time and the view of Jupiter and the Moon. 

 Similar views will be seen elsewhere at the equivalent local time (90 minutes after sunset). click to embiggen.

Evening sky at 22:00 ACST  on Saturday, September 26 facing east as seen from Adelaide. Mars is above the eastern horizon. The variable start Mira is visible to the unaided eye now, should be at its predicted maximum brightness.

The inset shows the telescopic view of Mars at this time.


Similar views will be seen elsewhere in Australia at the equivalent local time, click to embiggen.

Morning sky on
Thursday, October 1 showing the north-eastern sky as seen from Adelaide at 4:57 am ACST (60 minutes before sunrise). Venus is close to the bright star Regulus in Leo.

The inset in the telescopic view of Venus at this time.

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


Mercury climbs higher in the evening twilight, and is seen readily above the bright star Spica. .

Venus is below the bright star Procyon and is coming closer to the bright star Regulus.

 Mars is visible in the morning sky to the north, It is now readily visible in the late evening sky but is still best after midnight. Mars is close to the brightening variable star Mira.
  
Jupiter can be readily seen in the early evening sky. Jupiter and Saturn stay around a hand-span apart during the week and the pair dominate the evening skies. Jupiter was at opposition, when it was biggest and brightest as seen from Earth, on July the 14th, but is still an excellent sight. On the 24th the Moon forms a line with Jupiter and Saturn. On the 25th the Moon forms a triangle with Jupiter and Saturn. On the 26th the line is Jupiter, Saturn and Moon.
 
Saturn is too is now visible in the early evening skies. Saturn was at opposition, when it was biggest and brightest as seen from Earth, on July the 21st, but is still an excellent sight. On the 24th the Moon forms a line with Jupiter and Saturn. On the 25th the Moon forms a triangle with Jupiter and Saturn. On the 26th the line is Jupiter, Saturn and Moon.

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/

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Tuesday, September 15, 2020

 

Thursday September 17 to Thursday September 24

The New Moon is Thursday September 17, the First Quarter Moon is Thursday September 24. The bright planets Venus and Mars are visible in the early morning skies. Venus is below the bright star Procyon. While brightening Mars is rising well before midnight, Jupiter and Saturn still dominate the evening sky. On the 24th the Moon forms a line with Jupiter and Saturn. Mercury climbs towards the bright star Spica in the evening twilight. On the 19th Mercury and the crescent Moon form a triangle with Spica. On the 22nd Mercury and Spica are extremely close.

The New Moon is Thursday September 17, the First Quarter Moon is Thursday September 24.On the 18th the Moon is at perigee, when it is closest to Earth. Earth is at Equinox of the 22nd, when day and night are of equal length.

Evening sky at 19:05 ACST (60 minutes after sunset) on Saturday, September 19 facing west as seen from Adelaide. Mercury is easily seen above the Western horizon in the late twilight. Mercury forms a triangle with the bright star Spica and the crescent Moon.


 

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


Evening sky at 19:07 ACST (60 minutes after sunset) on Wednesday, September 22 facing west as seen from Adelaide. Mercury is easily seen above the Western horizon in the late twilight. At this time Mercury is spectacularly close to the bright star bright star Spica. The inset is the binocular view of the pair. They will also fit in moderate power telescope fields, but Mercury will be too small to show any detail.

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

Whole sky at 19:38 ACST on Thursday (90 minutes after sunset), September 24 as seen from Adelaide.

Three bright planets are visible stretching west to east. Jupiter, Saturn and Mars.  The Moon forms a line with Jupiter and Saturn. The insets show the telescopic views of Jupiter and Saturn at the same magnification at this time.

 Similar views will be seen elsewhere at the equivalent local time (90 minutes after sunset). click to embiggen.
 

Evening sky at 22:00 ACST  on Saturday, September 19 facing east as seen from Adelaide. Mars is above the eastern horizon. The variable start Mira is visible to the unaided eye now, as it brightens ahead of its maxim later this month.

The inset shows the telescopic view of Mars at this time.


Similar views will be seen elsewhere in Australia at the equivalent local time, click to embiggen.

Morning sky on Saturday, September 19 showing the north-eastern sky as seen from Adelaide at 5:15 am ACST (60 minutes before sunrise). Venus is below the bright star Procyon

The inset in the telescopic view of Venus at this time.

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


Mercury climbs higher in the evening twilight, and is seen readily below the bright star Spica. On the 19th Mercury and the crescent Moon form a triangle with Spica. On the 22nd Mercury and Spica are spectacularly close.

Venus is below the bright star Procyon.

 Mars is visible in the morning sky to the north, It is now readily visible in the late evening sky but is still best after midnight. Mars is close to the brightening variable star Mira.
  
Jupiter can be readily seen in the early evening sky. Jupiter and Saturn stay around a hand-span apart during the week and the pair dominate the evening skies. Jupiter was at opposition, when it was biggest and brightest as seen from Earth, on July the 14th, but is still an excellent sight. On the 24th the Moon forms a line with Jupiter and Saturn.
 
Saturn is too is now visible in the early evening skies. Saturn was at opposition, when it was biggest and brightest as seen from Earth, on July the 21st, but is still an excellent sight.

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/

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Monday, September 07, 2020

 

Thursday September 10 to Thursday September 17

The Last Quarter Moon is Thursday, September 10 and the New Moon is Thursday September 17. The bright planets Venus and Mars are visible in the early morning skies. Venus is below Orion and the bright star Procyon. Venus is visited by the thin crescent Moon on the 14th.While brightening Mars is rising well before midnight, Jupiter and Saturn still dominate the evening sky. Mercury climbs towards the bright star Spica in the evening twilight.

The Last Quarter Moon is Thursday, September 10, the New Moon is Thursday September 17.
 
Evening sky at 18:59 ACST (60 minutes after sunset) on Saturday, September 12 facing west as seen from Adelaide. Mercury is easily seen low above the Western horizon in the late twilight. Mercury will climb higher in the evening twilight becoming much easier to see as it heads for the bright star Spica.


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

 
 
Whole sky at 22:00 ACST on Saturday, September 12 as seen from Adelaide.

Three bright planets are visible stretching west to east. Jupiter, Saturn and Mars.  The insets show the telescopic views of Jupiter and Saturn at the same magnification at this time.
 
 
 
 
Similar views will be seen elsewhere at the equivalent local time. click to embiggen.
 

Evening sky at 22:00 ACST  on Saturday, September 12 facing east as seen from Adelaide. Mars is above the eastern horizon. The variable start Mira should be visible to the unaided eye now, as it brightens ahead of its maxim later this month.

The inset shows the telescopic view of Mars at this time.


Similar views will be seen elsewhere in Australia at the equivalent local time, click to embiggen.

Morning sky on Monday, September 14 showing the north-eastern sky as seen from Adelaide at 5:22 am ACST (60 minutes before sunrise). Venus is below the bright star Procyon and close to the thin crescent Moon.  The beautiful beehive cluster is between the two, but will only be visible in binoculars.

The inset in the telescopic view of Venus at this time.

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


Mercury climbs higher in the evening twilight, and should is seen readily below the bright star Spica.

Venus is below the bright star Procyon and close to the thin crescent Moon on the 14th.

 Mars is visible high in the morning sky to the north, It enters the evening sky in the late evening but is still low to the horizon until after midnight. Mars is close to the brightening variable star Mira.
  
Jupiter can be readily seen in the early evening sky. Jupiter and Saturn stay around a hand-span apart during the week and the pair dominate the evening skies. Jupiter was at opposition, when it was biggest and brightest as seen from Earth, on July the 14th, but is still an excellent sight. 
 
Saturn is too is now visible in the early evening skies. Saturn was at opposition, when it was biggest and brightest as seen from Earth, on July the 21st, but is still an excellent sight.

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/

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