Astroblog

The morning sky facing east in Adelaide on on Wednesday February 24 as seen from Adelaide at 6:01 ACDST, 60 minutes before sunrise, Saturn, Jupiter and Mercury are together low in the morning sky. (similar views will be seen Australia wide 90 minutes before sunrise,click to embiggen).

The February edition of Southern Skywatch is now up.

 In February most of the planetary action is low in the morning twilight.

February 4; Moon at perigee. February 6: Venus and Saturn close, low in the morning twilight. February 11; crescent Moon close to Venus.. February 14; Saturn, Jupiter, Venus and Mercury, close low in the morning twilight sky. February 19; Mars and First Quarter Moon close. February 18; Moon at Apogee. February 24; Saturn, Jupiter, and Mercury, close low in the morning sky. February 28; Mars within binocular range of Pleiades.

 Mercury is initially difficult to see low in the morning twilight.in the latter half of the month it becomes easier to see between Jupiter and Saturn.

Venus is close to the crescent Moon on the 11th low in the morning twilight with Jupiter below. On the 14th Saturn Jupiter and Venus for a line with Mercury forming a triangle with Jupiter and Venus. Venus is then lost i the twilight. 

Mars is close to the Moon on the 19th. Mars is within binocular range of Pleiades on the 28th.

 Jupiter starts low in the morning twilight and becomes easier to see. On the 11th Venus is close to the crescent Moon low in the morning twilight with Jupiter below. You will need a flat, unobstructed horizon like the ocean or desert to see this, and may require binoculars to see the planets clearly. On the 14th Saturn Jupiter and Venus for a line with Mercury forming a triangle with Jupiter and Venus. .

Saturn returns to the morning twilight early in the month. On  February 6, Venus and Saturn are close.
. On the 14th Saturn Jupiter and Venus for a line with Mercury forming a triangle with Jupiter and Venus. On February 24th Saturn, Jupiter, and Mercury, are close low in the morning sky.

February 4; Moon at perigee.  February 18; Moon at Apogee.

 

Labels: southern skywatch

Karuna names for constellations and stars on January 26 at astronomical twilight from Adelaide (10 pm ACDST) similar views will be seen around Australia at astronomical twilight (90 minutes after sunset)	Western equivalent names for constellations and stars on January 26 at astronomical twilight from Adelaide (10 pm ACDST) similar views will be seen around Australia at astronomical twilight (90 minutes after sunset)

If you are out and about tonight watching the fireworks or just wandering, you may want to look up and think about the sky from an indigenous perspective.

When the first fleet arrived the Europeans and the indigenous inhabitants saw the same wondrous skies but interpreted them somewhat differently. Indigenous Australians used the stars to tell the seasons and the times for food harvesting in much the same way as the ancient Greeks and Egyptians did (although the practice had waned somewhat by the time of the First Fleet as Europeans used almanacs rather than the helical rising of the dog star Sirius). 

They also saw stories in the stars, just as the Europeans did (although most of the European stories came from the ancient Greeks and Romans). These stories played a more immediate role in indigenous culture than the sky stories did for the Europeans.

The biggest difference was the "dark constellations", figures made from the gaps in the sky, the dark nebula interrupting the arch of the Milky Way. They are not Unique to Australia though, most other Southern Hemisphere indigenous groups have them.

The most famous one is the Emu, a sprawling constellation whose head is the coal sack nebula, whose neck and body is the dark lanes of the milky way, with a fringe of feathers that is the Northern Hemisphere constellation Scorpius. if you look up tonight you will only see the Emus head rising below the Southern Cross.

Indigenous Australians were astute observers of the sky, and were able to follow the changes in light of variable stars, and may have recorded an outburst of eta Carina. There is even a stone circle, Wurdi Youang,  that was probably used for astronomical observations in Victoria.

Of course, there is no single "Aboriginal Astronomy", Indigenous Australians had many nations, living in environments from Mediterranean climates to the south, wet temperate forests, deserts, subtropical to tropical forests, and monsoonal grasslands. The names of celestial objects, their stories and significance differ from place to place, a star that signifies the malee fowl nesting will have a different meaning in landscapes with no malee fowl.

I am currently living on and writing this on Karuna land on the Le Fevre Peninsula (I grew up on Murri lands). Looking up tonight towards the north I will see Tinniinyaranna, the Hunting Youths, they form Orion's belt and Sword in the European tradition.Below them is their mother Madletaltarni (Betelgeuse) and above then their fater, Parnakkoyerli (probably Rigel). To the west is Mankamankarranna, a group of girls digging for roots,  the Pelaides star cluster in Western star lore. 

Looking South I can see Wilto, the eagles claw, which we identify as the Southern Cross, with the dark nebula the coal sack nebula, which from the head of the Emu, directly below. Almost due south and just belwo the bright stars Canopus and Achenar are the patches of light that form the Magellanic clouds, Dwarf galaxies that orbit the Milky Way (Wodliparri). One or both of the Magellanic clouds are Ngakallamurro, ashes of parakeets roasted by another sky dweller. 

So so take a moment to look up tonight, and gaze upon the constellations and stars named and observed by indigenous Australians millennia before Europeans arrived. 

If you want to know more about indigenous astronomy Australian Indigenous Astronomy has lots of good content and links.

Stellarium is a good, free  skymap program that has many indigenous sky representations, including the Boorong people of western Victoria.

Labels: constellations, indigenous astronomy, public outreach, unaided eye

Morning sky on Saturday, January 30 showing the eastern sky as seen from Adelaide  at 6:05 am ACDST (30 minutes before sunrise). Venus is getting lower to the horizon. You will need a level, unobstructed horizon to see this.  

Labels: weekly sky

Labels: weekly sky

Evening sky at 22:14 ACDST  (90 minutes after sunset) on Saturday, January 16 facing north as seen from Adelaide. Mars is the brightest object above the north-western horizon. Uranus is within a binocular field of Mars. Similar views will be seen elsewhere in Australia at the equivalent local time (90 minutes after sunset), click to embiggen.	Evening sky at 22:11 ACDST  (90 minutes after sunset) on Tuesday, January 19 facing north as seen from Adelaide. Mars is the brightest object aside from the Moon above the north-western horizon. Uranus is just above Mars, Similar views will be seen elsewhere in Australia at the equivalent local time (90 minutes after sunset), click to embiggen.	<- td="">Evening sky at 22:10 ACDST  (90 minutes after sunset) on Thursday, January 21 facing north as seen from Adelaide. Mars is the brightest object above the north-western horizon and is just below the apogee First Quarter moon. Uranus is between the pair, in binoculars, Uranus is the brightest object aide from Mars and the Moon in the binocular field. Similar views will be seen elsewhere in Australia at the equivalent local time (90 minutes after sunset), click to embiggen.
Approximate binocular view of Mars and Uranus as seen with 10x50 binoculars on on Saturday, January 16, click to embiggen.	Approximate binocular view of Mars and Uranus as seen with 10x50 binoculars on on Tuesday, January 19, click to embiggen.	Approximate binocular view of apogee First Quarter Moon, Mars and Uranus as seen with 10x50 binoculars on on Thursday, January 21, click to embiggen.

From now until roughly January 27 will be a good time to view Uranus.  Although Uranus is bright enough to be (just) visible to the naked eye at magnitude 5.7, finding it can be quite difficult. Over the next few days we have a very bright signpost, Mars, to guide us. Between now and Wednesday 27 January Mars will be within binocular distance of Uranus. On the 21st, Uranus will be between Mars and the Moon, and within a wide field telescope objective field of view from Mars. With a telescope you should see Uranus as a tiny disk.

 During this time Uranus is the brightest object aside from the star 19 Arietis (which is approximately as bright as Uranus) in the constellation of Aires, the Ram) and of course the Moon, within binocular  range of Mars, but Uranus is easily distinguished as it is above Mars.

Binocular Spotter map suitable for printing (click it to embiggen and print) shows the nights Mars is within binocular range of Uranus (the large circle is the field of view of 10x50 binoculars the small the field of view of a 30mm telescope lens). Use the chart with a red light (or a torch with red cellophane over the end) so as not to interrupt your night vision.

The 21st is also the night of the apogee First Quarter moon, so you might like to try your hand at imaging Mars and Uranus.

 

Labels: binocular, Mars, Moon, Uranus

Full Moon January 29, 0:500 AEST	Full Moon February 27 18:00. Minimum libration -30h	Full Moon March 29 05:00 AEST, Perigee +35h March 10.
Full Moon April 27 14:00, perigee April 28 + 11h	Full Moon May 26 21:00, perigee May 26 -9h Total Lunar Eclipse. 21:10	Full Moon June 25 05:00, perigee June 23 -24h
Full Moon July 24 13:00.	Full Moon August 22 22:00. Maximum Libration +24 h	Full Moon September 21 10:00.
Full Moon October 21 01:00,	Full Moon November 19 19:00, apogee +41h. Twilight Partial Lunar eclipse	Full Moon December 19 15:00 Moon at apogee 18th -26h

 A year of full Moons showing the variation in size as the moons move from perigee to apogee. All the moons are shown on the day and time (AEST) they are full (unless they are below the horizon, in which case the size at astronomical twilight is shown), and although this is not the optimal time for size comparisons, you can clearly see the size difference over the year (compare April 27 to November 19) the original scale for all is 2 degrees of field of view cropped down to about two lunar diameters width). Although the field rotation of the Moon makes it less clear, you can also see the effect of libration.

In 2021 we have two good Perigee Moon is a row (April 27, May 26). One of which is a total Lunar Eclipse Moon (May 26). However, as you can see the differences are subtle, and it requires a keen eye and good memory to distinguish a perigee "super" Moon from more ordinary moons, the best contrast is with the apogee "mini" moons of November 19/December 19).

That doesn't mean you shouldn't try though. Daniel Fischer has been able to see the difference, you can read his account and viewing tips here
http://earthsky.org/space/can-you-discern-supermoons-large-size-with-the-eye-an-observer-says-yes

Photographing them can be more rewarding. You can see images of perigee Moon and apogee Moon pairs from 21 Jan 2019 here and 10 August 2014 here.Tips for photographing them are here.

Labels: apogee, Blue Moon, Moon, perigee, public outreach, unaided eye, Yearly Moons

This years apogee and perigee First Quarter Moons. Apogee FQ is on January 21st at 11 pm AEST (not 11am as on the diagram), and official First Quarter is at 7 am AEST, 13 hours apart.  Perigee FQ is further apart, official first quarter is at 1 am on the August 16th, and Perigee on the August 17th at 7 pm, 1 day and 18 hours apart. 

Because the Moons orbit is elliptical, there are times when it is  furthest from the Earth (apogee) and closest to the Earth (perigee). At these time the Moon is different in size as seen from Earth, the difference is subtle to the unaided eye, but readily seen in binoculars or telescope.

Until recently most people didn't give perigee and apogee Moons a second thought, but after they were invoked in some pseudoscience waffle, they were co-opted by the astronomical community to get people more interested in the sky, with perigee Full Moons becoming "Super" Moons.  

Of course, the "Super Moon" (and "mini" apogee moon)  focuses on the really obvious full Moon, but the other moon phase can occur at perigee and apogee too. Of course you can't see either a perigee or apogee new Moon (unless there is a total Solar Eclipse or annular solar eclipse from an apogee New Moon) and no one want's to get up at Dark O'Clock to see a Last Quarter Perigee or apogee Moon. But first Quarter? 

Ahh that's a different story. 

Last quarter Moons are relatively high in the sky at sunset, so you don't have to wait a while for the moon to get high enough to dispel the Moon Illusion so you don't confuse the illusion with the Moon's true size. Also, unlike the full moon, where there are no shadows and everything is a bit bland (if beautiful). 

But the First Quarter Moon is more dramatic, with the shadows of the terminator bringing out the walls of the craters and the mountain peaks. Of course this is not all visible to the unaided eye, but in binoculars or even a small telescope the view is beautiful and reveals the size difference between the apogee and perigee Moon more easily. 

This year the First Quarter Perigee is a bit over a day and a half after First Quarter 16th and 17th August), but still not bad, and apogee and First Quarter is only 13 hours apart (upcoming at 21 January). Next year the pairing is March 10 apogee, November 1 perigee.

Anyway, try your hand at discerning the size difference between the upcoming apogee First Quarter Moon and the August perigee First Quarter Moon. Tips for photographing them are here.

Labels: apogee, Moon, perigee

Labels: weekly sky