Astroblog

The north-eastern horizon as seen from Adelaide at 5:00 am ACST, the eta Aquariid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at the equivalent local time (click to embiggen). 

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People in the suburbs should see a meteor around once every 6 minutes, and in the country about once every 3-4 minutes. The radiant of the shower is about five hand-spans up from the eastern horizon, and three hand-spans to the left of due east at 4 am (see spotter chart at 5:00 am above). The radiant is close to Saturn, with Venus below, which makes a good reference point.

Weather prediction looks okay.

You may have read that this year the eta Aquariids have a predicted ZHR of 50 meteors. 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 was dark enough for 6.5-magnitude stars to be visible to the naked eye.

In practice, 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. How many are you likely to see in reality? 

The table below gives predictions below for various towns, but they are only predictions and while based on average steam density there may be some differences year to year, but good rates were seen in previous years, and dark sky sites may possibly see one meteor every 3-4 minutes or so. There were many bright ones reported with persistent trains in 2014. People in the suburbs maybe will see less, but at least one every 6 minutes should be possible. 

Predicted meteor rates for selected towns (taken from NASA shower Flux estimator below). If your city is not on the list you can expect a meteor rate similar to the closest city to you in latitude.

Town	Morning May 6	Morning May 7	Morning May8
Adelaide	15 meteors/hr	18 meteors/hr	19 meteors/hr
Brisbane	16 meteors/hr	19 meteors/hr	21 meteors/hr
Darwin	17 meteors/hr	20 meteors/hr	22 meteors/hr
Perth	16 meteors/hr	19 meteors/hr	20 meteors/hr
Melbourne	15 meteors/hr	17 meteors/hr	18 meteors/hr
Hobart	14 meteors/hr	17 meteors/hr	18 meteors/hr
Sydney	15 meteors/hr	18 meteors/hr	20 meteors/hr

The radiant of the shower is about five hand-spans up from the eastern horizon and three hand-spans to the left of due east at 4 am (see above for a spotter chart at 5 am). 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. The best way to watch the Eta Aquariids is to let your eye rove around the entire patch of the sky above the north-east horizon, between the only two obvious bright stars in the northeast, Altair and Fomalhaut, and Saturn as the center of your field (again, see the spotter chart at 5:00 am above). The meteors are fast, with few fireballs and persistent trains.

Be patient, although you should see an average of a meteor every 3 to 4 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 Milky way will arch above you, with Saturn and Venus just below the radiant.

Use the NASA  meteor shower flux estimator for an estimate of what the shower will be like from your location (you may need to enter your longitude and latitude, surprisingly, while Adelaide and Brisbane are hard-wired in, Sydney and Melbourne are not). See the image to the left for typical output. The peak is rather sharp.

 

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Labels: eta aquarid, Meteors, unaided eye

# posted by Ian Musgrave @ 9:53 pm 0 comments

The First Quarter Moon is Sunday May 4.  Jupiter and Mars are visible in the evening sky. Jupiter is close to the crescent moon on the 1st. Mars is high in the early evening sky and on the 4th and 5th Mars is close to the Beehive cluster. On the 4th Mars is also close to the first quarter Moon. Look for the constellation Corona Borealis before midnight, the blaze star T Coronae Borealis (TCrB) may go Nova eventually.  The asteroid Vesta is visible nearby and is at opposition on the 2nd. Saturn, Venus and Mercury are visible in the morning twilight. The eta Aquariid meteor shower peaks on the 7th.

The First Quarter Moon is Sunday May 4.   

Eastern twilight sky on the morning of Saturday, May 3 as seen from Adelaide at 05:52 ACST (60 minutes before sunrise, click to embiggen).

Saturn is visible in the twilight near Venus with  the crescent moon close to Mercury below. 

 

 

 

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

 

The north-eastern horizon as seen from Adelaide at 5:00 am ACST on 7 May, the eta Aquariid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at the equivalent local time (click to embiggen). 

The eta Aquariid meteor shower, which is produced by the debris from Halley’s Comet, will peak on May 7 (strictly speaking May 6, 3UT). dark sky sites could expect to see meteor every 3-4 minutes. Good rates will also be seen on the 8th.

 

 For more details and rates see my Eta Aquariids page.

 

 

 

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

If you look to the North just before midnight, you will see a prominent bright orange star, Arcturus, if you look northeast you will see a dainty circlet of stars. Corona Borealis, the northern crown. The blaze star T CrB is located on the right-hand side to the circlet, where the line of stars turns down, there are no other bright stars in the region, so when it erupts it will be easily visible. Viewing tips at my T CrB post. 

Just above this is the asteroid Vesta, at opposition on the 2nd and theoretically visible to the unaided eye. it is roughly between the bright red Star Antares and Arcturus, two binocular widths from the bright star Beta Librae. The inset shows the approximate binocular view of Vesta, near the star 16 Librae. See my opposition of Vesta page for more details and charts. 

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

 

North-western sky on Thursday, May 1 as seen from Adelaide at 18:30 ACST (60 minutes after sunset, click to embiggen). Jupiter is in the north-west forming a line with the star Aldebaran and the crescent Moon. Mars forms a crooked line with Castor and Pollux.

 

 

 

 

 

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

 

North-western sky on Sunday, May 4 as seen from Adelaide at 18:56 ACST (90 minutes after sunset, click to embiggen). Mars is close to the First Quarter Moon and the Beehive cluster (M44).

 

The inset is the binocular view of Mars and the Beehive cluster on the 5th when the Moon has moved away.  (click to embiggen).   

 

 

 

 

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

 

Whole sky on Saturday, May 3 as seen from Adelaide at 18:57 ACST, 90 minutes after sunset (click to embiggen).

Jupiter is low in the north-west.  Mars is in the north. 

 

Orion the hunter is lowering in the north-west as Scorpius rises in the east.

 

The Southern Cross is rising in the Southern sky.  The moon is almost new and the fainter clusters and nebula are becoming easier to see.      

 

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

 

 

Mercury begins sinking in the morning twilight. 

Venus climbs higher in the morning twilight. It forms a pair with Saturn.

Mars is high in the evening sky. Mars is close to the First Quarter Moon and the Beehive cluster (M44) on the 4th.

Jupiter is sinking in the the north-western evening sky when the sky is fully dark. Jupiter forms a line with the crescent moon on May 1. 

Saturn is rising in the morning the twilight. It forms a pair with 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 @ 11:43 pm 0 comments

Evening sky from Friday, May 2 as seen from Adelaide at 17:59 ACST (30 minutes after sunset), C/2025 F2 SWAN is present in the twilight although not likely visible.  In the coming days it will rise higher in the twilight but will only be a binocular object at best. Similar views will be seen from the rest of Australia at roughly the equivalent local time (30minutes after sunset, click to embiggen).	Evening sky on Tuesday, May 6 as seen from Adelaide at 18:25 ACST (60 minutes after sunset),  C/2025 F2 SWAN may be visible in the twilight in binoculars in the Hyades. The inset is the approximate binocular view at this time. Similar views will be seen from the rest of Australia at roughly the equivalent local time (60 minutes after sunset, click to embiggen).	Evening sky on Monday, May 12 as seen from Adelaide at 18:20 ACST (60 minutes after sunset), C/2025 F2 SWAN may be just visible in the twilight in binoculars in Orion's Shield. The inset is the approximate binocular view at this time. Similar views will be seen from the rest of Australia at roughly the equivalent local time (60 minutes after sunset, click to embiggen).
Path of C/2025 F2 SWAN in the western evening sky from Friday, May 2 to 1 June as seen from Adelaide at 17:59 ACST (30 minutes after sunset. Black&White chart suitable for printing. The image is at civil twilight to show the path of the comet over the month, however, the best time to observe is nautical twilight (60 minutes before sunrise). The greyed out section is below the horizon. (click to embiggen and print).	Binocular chart of the path of C/2025 F2 SWAN in the western evening sky from 6 May to 11 May. Black&White chart suitable for printing (click on the image to embiggen and print). The image is at nautical twilight (60 minutes before sunrise). The circle is the approximate field of view of 10x50 binoculars.	Biinocular chart of the path of C/2025 F2 SWAN in the western evening sky from 10 May to 19 May. Black&White chart suitable for printing (click on the image to embiggen and print). The image is at nautical twilight (60 minutes before sunrise). The circle is the approximate field of view of 10x50 binoculars.

If comet C/2025 F2 SWAN survives perihelion on the 1st of May, it will be visible low in the twilight. Unlike comet C/2024 G3 it will not be visible to the unaided eye, even through theoretically visible (magnitude 6), its position low in the twilight murk means binoculars will always be needed. 

You will need a clear, level horizon like the ocean or desert to see the comet. It will fade rapidly after perihelion. This and its location in the horizon murk means the window of opportunity for binocular viewing is narrow.

The earliest we can reasonably see the comet here in Australia is May 6th, when it is roughly 5 degrees (about a hand-span) above the western horizon at nautical twilight. Although roughly magnitude 6 it will be hard to see in the twilight. 

As C/2025 F2 SWAN passes through the Hyades in Taurus and into Orion it will rise into darker skies, but be fading fast, so sill be difficult to see, despite good guide stars. See printable charts above. 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.

Labels: binocular, C/2025 F2, comet

# posted by Ian Musgrave @ 11:27 pm 1 comments

Evening sky on Friday, May 2 as seen from Adelaide at 23:00 ACST. Asteroid Vesta is at apposition in Libra.  The inset is the binocular view of Vesta at this time. At magnitude 5.7 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 wide field binocular view of Vesta and the guide stars at 23:00 ACST from Friday, April 25 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 North suitable for printing showing the guide objects of 4 Vesta, Antares, 𝛃 Librae (Zubeneschamali), μ Virginis (Rijl Al Awwa, unlabeled in this view) and Arcturus as seen from Adelaide at 23:00 ACST at Saturday 25 April. 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 April-May. 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 5.7 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 Friday, May 2 is a  good opposition of Vesta, when it will reach a magnitude of 5.7 at its brightest with reasonable guide stars and no Moon interference.

Labels: 4 Vesta, Asteroid, binocular

# posted by Ian Musgrave @ 3:28 pm 0 comments

The New Moon is Monday April 28.  Jupiter and Mars are visible in the evening sky. Jupiter forms a line with the stars Aldebaran and Elnath and sets early evening. Mars is high in the early evening sky forming a line with the bright stars Castor and Pollux as it heads towards Cancer. Look for the constellation Corona Borealis before midnight, the blaze star T Coronae Borealis (TCrB) may go Nova eventually.  The asteroid Vesta is visible nearby. Saturn, Venus and Mercury are visible in the morning twilight. The Crescent Moon is close to Venus and Saturn on the 25th, the mercury on the 26th.

The New Moon is Monday April 28. The Moon isat perigee, when it is closest to the earth, on the 28th as well. 

The crescent Moon forms a triangle with Saturn and Venus. Mercury is below

The inset is the telescope view of Venus at this time.  (click to embiggen).

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

 

Eastern twilight sky on the morning of Saturday, April 26 as seen from Adelaide at 05:52 ACST (60 minutes before sunrise, click to embiggen).

Saturn is visible in the twilight near Venus with  the crescent moon close to Mercury below. 

 

 

 

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

If you look to the North just before midnight, you will see a prominent bright orange star, Arcturus, if you look northeast you will see a dainty circlet of stars. Corona Borealis, the northern crown. The blaze star T CrB is located on the right-hand side to the circlet, where the line of stars turns down, there are no other bright stars in the region, so when it erupts it will be easily visible. Viewing tips at my T CrB post. 

Just above this is the asteroid Vesta, nearing opposition and theoretically visible to the unaided eye. it is roughly between the bright red Star Antares and Arcturus, two binocular widths from the bright star Beta Librae. The inset shows the approximate binocular view of Vesta, near the star 16 Librae.

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

 

North-western sky on Saturday, April 26 as seen from Adelaide at 19:04 ACST (90 minutes after sunset, click to embiggen). Jupiter is in the north-west forming a line with the stars Aldebaran and Elnath; Mars forms a crooked line with Castor and Pollux.

 

The insets are the telescope views of  Jupiter and Mars at this time.  (click to embiggen).   

 

 

 

 

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

 

North-western sky on Thursday, May 1 as seen from Adelaide at 18:30 ACST (60 minutes after sunset, click to embiggen). Jupiter is in the north-west forming a line with the star Aldebaran and the crescent Moon. Mars forms a crooked line with Castor and Pollux.

 

 

 

 

 

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

 

Whole sky on Saturday, Saturday, April 26 as seen from Adelaide at 19:04 ACST, 90 minutes after sunset (click to embiggen).

Jupiter is low in the north-west.  Mars is in the north. 

 

Orion the hunter is lowering in the north-west.

 

The Southern Cross is rising in the Southern sky.  The moon is almost new and the fainter clusters and nebula are becoming easier to see.      

 

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

 

 

Mercury begins sinking in the morning twilight. It is close to the crescent moon on the 26th.

Venus climbs higher in the morning twilight. It forms a pair with Saturn and a triangle with the crescent moon on the 25th.

Mars is high in the evening sky. Mars forms a crooked line with the bright stars Castor and Pollux.

Jupiter is sinking in the the north-western evening sky when the sky is fully dark. Jupiter forms a line with the stars Aldebaran and Elnath, then with the crescent moon on May 1. 

Saturn is rising in the morning the twilight. It forms a pair with Venus and a triangle with the crescent moon on the 25th.

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 @ 1:52 am 0 comments

The Last Quarter Moon is Monday April 21.  Jupiter and Mars are visible in the evening sky. Jupiter forms a line with the stars Aldebaran and Elnath and sets mid evening. Mars is high in the early evening sky forming a line with the bright stars Castor and Pollux. Look for the constellation Corona Borealis in the morning skies, the blaze star T Coronae Borealis (TCrB) may go Nova eventually.  Saturn, Venus and Mercury are visible in the morning twilight. Mercury is close to Neptune on the 17th and 18th and  at its highest on the 22nd.

The Last Quarter Moon is Monday April 21. 

Saturn is visible in the twilight forming a triangle with Mercury and Venus. Mercury is close to Uranus

The inset is the binocular view of Mercury and Uranus  at this time.  (click to embiggen).

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

 

Eastern twilight sky on the morning of Thursday, April 24 as seen from Adelaide at 05:51 ACST (60 minutes before sunrise, click to embiggen).

Saturn is visible in the twilight close to Venus with Mercury below. The waning moon is above making a nice lineup.

The inset is the telescope view of Venus at this time.  (click to embiggen).

 

 

 

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

 

If you look to the North at astronomical twilight (90 minutes before sunrise), you will see a prominent bright white star, Vega, if you look northwest you will see a dainty circlet of stars. Corona Borealis, the northern crown. The blaze star T CrB is located on the right-hand side to the circlet, where the line of stars turns down, there are no other bright stars in the region, so when it erupts it will be easily visible. Viewing tips at my T CrB post.

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

 

North-western sky on Saturday, April 19 as seen from Adelaide at 19:11 ACST (90 minutes after sunset, click to embiggen). Jupiter is in the north-west forming a line with the stars Aldebaran and Elnath; Mars forms a line with Castor and Pollux.

 

The insets are the telescope views of  Jupiter and Mars at this time.  (click to embiggen).   

 

 

 

 

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

 

Whole sky on Saturday, Saturday, April 19 as seen from Adelaide at 19:11 ACST, 90 minutes after sunset (click to embiggen).

Jupiter is in the north-west.  Mars is in the north. 

 

Orion  the hunter is lowering in the north-west.

 

The Southern Cross is rising 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 climbs higher in the morning twilight. Mercury is close to Neptune on the 17th and 18th and  at its highest on the 22nd.

Venus climbs higher in the morning twilight. It forms a pair with Saturn.

Mars is high in the evening sky. Mars forms a line with the bright stars Castor and Pollux.

Jupiter is sinking in the the north-western evening sky when the sky is fully dark. Jupiter forms a line with the stars Aldebaran and Elnath. 

Saturn is rising in the morning the twilight. It forms a pair with 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 @ 6:41 pm 0 comments

The Full Moon is Sunday April 13.  Jupiter and Mars are visible in the evening sky. Jupiter forms a line with the stars Aldebaran and Elnath and sets in the late evening. Mars is high in the early evening sky forming a line with the bright stars Castor and Pollux. Look for the constellation Corona Borealis in the morning skies, the blaze star T Coronae Borealis (TCrB) may go Nova eventually.  Saturn, Venus and Mercury are visible in the morning twilight. Mercury is close to Saturn between the 10th and 12th forming a triangle with Venus.

The Full Moon is Sunday April 13. Apogee, when the Moon is furthest from the earth, is on the 14th.

Saturn is visible in the twilight forming a triangle with Mercury and Venus. 

The inset is the telescope view of Venus at this time.  (click to embiggen).

If you look to the North-west at astronomical twilight (90 minutes before sunrise), you will see a prominent bright orange star, Arcturus, if you look northwardst you will see a dainty circlet of stars. Corona Borealis, the northern crown. The blaze star T CrB is located on the right-hand side to the circlet, where the line of stars turns down, there are no other bright stars in the region, so when it erupts it will be easily visible. Viewing tips at my T CrB post.

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

 

North-western sky on Saturday, April 12 as seen from Adelaide at 19:20 ACST (90 minutes after sunset, click to embiggen). Jupiter is in the north-west forming a line with the stars Aldebaran and Elnath; Mars forms a line with Castor and Pollux.

 

The insets are the telescope views of  Jupiter and Mars at this time.  (click to embiggen).   

 

 

 

 

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

 

Whole sky on Saturday, Saturday, April 12 as seen from Adelaide at 19:11 ACST, 90 minutes after sunset (click to embiggen).

Jupiter is in the north-west.  Mars is in the north. 

 

Orion  the hunter is lowering in the north-west.

 

The Southern Cross is rising 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 climbs higher in the morning twilight. On the 10th to the 12th Mercury is close to Saturn forming a triangle with Venus.

Venus climbs higher in the morning twilight. It is near to Mercury and Saturn

Mars is high in the evening sky. Mars was at opposition, when it is biggest and brightest as seen from Earth, on January the 16th. Mars forms a line with the bright stars Castor and Pollux.

Jupiter is sinking in the the north-western evening sky when the sky is fully dark. Jupiter forms a line with the stars Aldebaran and Elnath. 

Saturn is rising in the morning the twilight. On the 10th to the 12th Mercury is close to Saturn forming a triangle with 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 @ 9:03 pm 0 comments

The Lunar X and V (indicated) as visible in telescopic views. Click to embiggen for a clearer view.	Western evening sky on Saturday April 5 as seen from Adelaide at 23:17 ACDST	Western evening sky on Saturday April 55 as seen from Brisbane at 22:43 AEST
Sunrise on the Moon: Moon at 20:00 ACDST, the Lunar V is just visible.	Sunrise on the Moon: Moon at 21:00 ACDST, the Lunar V is becoming visible. Some crater walls are beginning to light up	Sunrise on the Moon: Moon at 21:00 ACDST, the Lunar V is  visible. Some crater walls are lighting up and the frist hints of the Lunar X are there

The Lunar X (also known as the Werner X) and the Lunar V will be visible this Saturday as the moon reaches First Quarter. The Lunar X is a chiaroscuro effect in which strong contrasts of light and shadow create the appearance of a letter 'X' on the rim of the Lunar craters Blanchinus, La Caille and Purbach and a letter V from the rim of the crater Ukert, along with several smaller craters. 

The X and V are seen at first quarter, visible on the lunar surface for about 4 hours. However, the Moon is not always above the horizon from a given vantage point when this happens. This month is okay for Australian observers, with the Moon low to the horizon in the eastern sates, and reasonably high on the west coast.

Lunar X occurs on Saturday April 5, 12:43 UT, 23:43 AEDST,  22:43 AEST, 23:17 ACDST, 22:17 ACST, 20:43 AWST). This is later than official first Quarter which occurs at 12:45 ACDST.

This is a telescope (and maybe good binoculars) only event. For the west coast the start of the Lunar X occurs with the Moon being 25° above the horizon, central states see it at 11° above the horizon, and for the east coast at 6° above the horizon.

Upcoming Lunar X' s are shown below:

Dates and time Lunar X and V are visible. Typically visible from about 4hours from the starting time, times in colour are daylight saving times.

If you are setting up to see the Lunar X, why not start early so you can watch sunrise on the Moon? You can watch the sides of crater walls light up as hours progressStarting from nautical twilight, an hour after sunset, image the Moon through binoculars of a telescope every hour until around moon set and you can see the walls of the Lunar V light up, then the walls of the X. 

Also if you are setting up early, catch the reappearance of Iota Geminorum from occultation by the Moon.

Iota Geminorum about to be occulted by the Moon as seen from Brisbane at 19:09 AEST	Iota Geminorum emerging from behind the Moon as seen from Brisbane at 20:09 AEST

Labels: Lunar X, Moon, telescope

# posted by Ian Musgrave @ 12:14 am 2 comments