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Tuesday, December 05, 2017

 

The Sky This Week - Thursday December 7 to Thursday December 14

The Last Quarter Moon is Monday, December 10. Mercury and Saturn are lost in the  twilight.  Mars is relatively easy to see and  is close to the thing crescent Moon on the 14th .Jupiter is now prominent in the morning sky and is heading towards the bright star alpha2 Librae. The Geminid meteor shower peaks on the morning of the 14th.

The Last Quarter Moon is Monday, December 10.

Evening sky on Saturday December 9 looking west as seen from Adelaide at 20:50 ACDST  (30 minutes after sunset). Mercury is low above the horizon and is close to  Saturn.

Similar views will be seen elsewhere in Australia at the equivalent local time (30 minutes after sunset). (click to embiggen).

Mercury is barely visible in early  twilight. You will need a low flat unobstructed horizon to see it. Mercury is below Saturn and this will be the last week to see them.

Saturn is visible low in the early evening twilight above Mercury and is lost to view by mid week.

Morning sky on  Thursday December 14 looking east as seen from Adelaide at 4:50 ACDST (60 minutes before sunrise). Jupiter is prominent and Mars can be seen close to the crescent Moon, between the bright star Spica and Jupiter.

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

Venus  is lost in the twilight.

Jupiter climbs higher in the morning twilight and is now becoming prominent.

 Mars is climbing higher the twilight, and is is coming closer to the bright star spica. The pair are closest on the 30th.

Geminids as seen from Brisbane facing north at 2:00 am AEST. The Geminid radiant is marked with a starburst . (similar views from elsewhere at equivalent local time eg Sydney 3:00 am AEDST, Adelaide 3:30 am).
 
Similar views will be seen elsewhere at equivalent local times. (click to embiggen).

The Geminids are a fairly reliable meteor and this will be a good year for them with little moon interference.

The radiant doesn't rise until just before midnight (daylight saving time) in most of Australia, so you will still have to disturb your sleep for this one. Australians should see a meteor every two to three minutes under dark skies in the early morning of the 14th, between 1:00 am and 4:00 am local time. The further north you are the better the meteor rates. You can find predictions for your local site at the meteor flux estimator (choose 4 Geminids and date 13-14 December, don't forget to change the year to 2017).

You can find more details on my Geminid page.

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.

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, December 02, 2017

 

The Perigee Moon ("Super Moon") of Monday December 4, What Can You See?

Due to travel to visit my mum and go to conferences, where I don't have access to my drawing programs, I have recycled an old post, so I don't have updated images.

Illustration of the orbit of the Moon around the Earth. Distances for apogee and perigee are given for the 2011 Full Moons because I was lazy (and am traveling) and didn't want to redraw the diagram.

By now you may have seen the stories that the  Full Moon of Monday, December 4 is a "Super Moon" (as is the Full Moon of January 1, 2018).

Technically,  the Moon will be at perigee, when it is closest to the Earth.

A full Moon at perigee has been called a "Super Moon", this is not an astronomical term (the astronomical term is perigee syzygy, but that doesn't trip off the tongue so nicely), but an astrological one first coined in 1979 (see here).

However, astronomical outreach groups started using the term "Super Moon" for perigee Moons and it stuck.

 Chart comparing the binocular/telescopic appearance of the November 2016 Full Perigee Moon with the apogee Moon of  April 21 2016. This year's perigee Moon on December 4 will be slightly smaller than the November 14 one. Click to embiggen.

What can you expect to see with the "Super Moon" of  December 4?

Not much really, unless you are a regular observer of the Moon, have good visual acuity and a good memory.

The problem is, while the Moon is close this time around, it doesn't actually translate into something you can easily see with your unaided eye. Mondays Full Moon will be around 14% larger and 30% brighter than Junes apogee Full Moon.

So how's your memory?

If you can remember back that far, and remember seeing the Full Moon on June 8, you now come up against the limits of human eyesight.

The limit of distances that someone with good vision can distinguish between is 1 minute of arc (about the width of a human hair). So, for the vast majority of people, any difference smaller than 1 minute of arc cannot be seen. The difference between the Apogee full Moon of 8 June (29'58") and this Mondays perigee "Super" full Moon (33'36") is around 3 minutes of arc, that is 3 human hair widths, doable for most people, but you do have to remember what the Moon looked like back in June, 8 months ago.

Some of my astronomical friends who are regular Moon viewers can do this. On the other hand, I have been trying to image perigee and apogee Moons for a couple of years, and I can never tell the difference.
That doesn't mean you shouldn't look 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

However, it will be a good photo opportunity, if you have a decent zoom on your camera or access to a small telescope. If you have not already taken an image on June 8,  taking a photo of the Moon on December 4 (Or Jan 1 2018, which is a better Perigee Moon) and then again on  July 27 in 2018  for the apogee "mini-Moon" you will see a decent difference (you need to use exactly the same zoom enlargement, see Inconstant Moon for instructions).

Here's my images from the January/August 2014 apogee and perigee Moons respectively.

 For a list of full/new Moons and the dates of apogee/perigee see here.

In contrast, the November 6th Full Moon, which you probably can remember,  was 32'45'' wide (compared to this months "Super Moon" of 33'36")  so the difference is less than one minute of arc, the Full Moon of October  5 was 32'11" wide, again around one minute of arc wide so you will not be able to tell the difference between these full Moons and this Monday's "Super Moon".

Recent perigee Full Moons compared to the close 2034 and 1948 perigee full Moons, note that there is only a handful of kilometres between them. (source)

Date   Time      Distance    Moon Phase      Year
Nov  25 22:08 356447 km  ++  F-    0h 2034
Jan  26 11:17 356462 km  ++  F+    4h  1948
Jan  1 21:56 356565 km ++ F-   4h 2018
Dec  4  8:43 357495 km +  F+  16h 2017
Nov 14 11:24 356511 km ++ F- 2h 2016
Mar 8 8:36 356529 km ++ F- 1h 1993
Jan 19 22:13 356548 km ++ F+ 0h 1992
Dec 12 21:38 356567 km ++ F+ 4h 2008
Mar 19 19:10 356577 km ++ F+ 0h 2011
Jan 30 9:04 356592 km ++ F+ 2h 2010
Nov 4 0:42 356614 km ++ F- 4h 1998
Dec 22 11:01 356654 km ++ F- 6h 2001
Dec 22 11:01 356654 km ++ F- 6h 1999
Oct 26 11:52 356754 km ++ F+ 6h 2007
Feb 7 22:20 356852 km ++ F- 8h 2002
Sep 28 1:47 356876 km ++ F- 1h 2015
Aug 10 17:44 356896 km ++ F- 0h 2014
Apr 25 17:18 356925 km ++ F- 2h 1994
Jul 30 7:37 356948 km ++ F- 2h 1996
May 6 3:34 356953 km ++ F- 0h 2012
Sep 16 15:25 356965 km + F- 3h 1997
Jun 23 11:11 356989 km ++ F- 0h 2013
Jun 13 1:06 357006 km + F- 2h 1995
Apr 17 4:59 357157 km + F+ 9h 2003
Jul 21 19:46 357159 km  F+ 8h 2005
Sep 8 3:08 357174 km + F+ 8h 2006
Jun 3 13:11 357248 km ++ F+ 8h 2004
Jan 10 10:53 357500 km + F- 16h 2009
Dec 22 9:29 358353 km  F+ 23h 1991
Nov 14 22:59 366050 km  F+3d 1h 2000

Another twist is that the time of perigee is 08:43 UT, which is 19:43 AEDST, the Moon doesn't rise until 20:25AEDST at night, when it is receding from us. The reason why I emphasise this is that many people will see the Moon rising on the horizon, where it will look bigger due to the Moon illusion and say "I've seen the super Moon", when no, they haven't, the Moon was "supersized" half an hour it rose.

While all but a few dedicated Moon watchers will be able to see the difference between this "Super Moon" and an apogee Moon with the unaided eye, photographing it is another thing entirely. Here are some images of the "Super Moon" of August 2014 that I took.   Again, it helps to have images of an apogee Moon to compare with, but you are going to have to wait until 8 June 2017 for your next apogee Moon opportunity.

However, as the Moon is rising it is also increasing in size, so a series of images could capture the size increase towards perigee. However, you WILL need a good zoom lens, binoculars or telescope to capture this, the magnification of an ordinary camera will be insufficient to pick up the size difference.

So, the "Super Moon" will be a little bit disappointing if you are not an obsessive Moon watcher with a good memory, but it will still be a beautiful Full Moon, and if you are handy with a camera and telescope you can capture the Moon as it increases in size, and if you capture next years apogee Moon you can make some nice contrasting images.

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Friday, December 01, 2017

 

Southern Skywatch December 2017 edition is now out!

Morning sky as seen on December 14, 60 minutes before sunrise. The crescent Moon is close to Mars and forms a triangle with Jupiter and Spica. Similar views will be seen elsewhere in Australia at the equivalent local time. (click to embiggen).

The December edition of Southern Skywatch is  now up.

This month  sees most of the action move to the morning sky. Speedy Mercury  and Saturn are lost in the twilight. 

 Mars and  Jupiter climb higher in the morning sky. Mars is close to the crescent Moon on the 14th, Jupiter is close to the Moon on the 15th. Jupiter is close to Alpha2 Libra on the 22nd. Mars is close to Alpha2 Libra on the 31st.

The Geminid meteor shower is active towards the middle of the month, with the best rates in the early morning of the 14th to 15th.

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Thursday, November 30, 2017

 

Astrophiz Podcast 48 (Star-forming frenzy edition) is Out!

Astrophiz Podcast 48 is out now.

In this fabulous extended 60min episode we feature Dr Jacinta Delhaize who is a Postdoctoral Researcher at University of Zagreb, Faculty of Science in Croatia.

Jacinta has devolved a ‘stacking technique’ to combine data to overcome the problem of detecting weak hydrogen signals from distant galaxies. She has been using data from the Parkes Dish and the Hershel instrument to helps us understand the role of hydrogen in the evolution of galaxies.

After recently moving from ICRAR in Western Australia to Croatia, her research is now looking at how black holes at the centres of galaxies can effect star formation, and is now using data from the Jansky VLA to continue this collaborative research. For observers and astrophotographers, I tell you what when and where to look for objects in the morning and evening skies over the next days and weeks, and how to best observe the imminent Geminid Meteor Shower.

In ‘ian’s tangent’ I tells you about Australia’s early eminence in Space with the 50th Anniversary of the launch of our first satellite, WRESAT

You can follow me  @ianfmusgrave on Twitter and southern skywatch on facebook.

Jacinta has an excellent youtube vid and you can see her describe her research on the infrared-radio correlation of galaxies at tinyurl.com/jdelhaize
Her website is at www.jacintadelhaize.com and she also has a public twitter and instagram account. Both are @jdelhaize

In the News: Teams of Radio astronomers and optical astronomers both research the Magellanic Clouds in the Southern hemisphere, and both teams come up with exciting discoveries.

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Tuesday, November 28, 2017

 

Geminid Meteor Shower 14-15 December 2017

The northern horizon at 4:00 am ACDST as seen from Adelaide on Thursday December 14. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at  a similar latitude and the equivalent local time. (click to embiggen).The northern horizon at 3:00 am AEDST as seen from Sydney on Thursday December 14. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at  a similar latitude and the equivalent local time. (click to embiggen).

The Geminids are unusual meteor shower in that their parent body is 3200 Phaethon, an asteroid, rather than a comet. It is speculated though that Phaeton is actually a "gassed out" comet, and so the debris that makes up the Geminids may still be cometary particles.
 
The Geminids are a fairly reliable meteor shower and this year moonlight will not interfere. Some decent meteors rates should be seen. 


Unlike the Leonids, where there is a very narrow peak of high activity, the Geminids have a broad peak and will show good activity well before and after the peak, and on the day before and after. The peak is December 14, 06h30m UT. That is 5 pm AEDST December 14 in Australia.  This is in daylight in Australia, but levels should remain good in the early morning so you should get decent rates. However, the radiant doesn't rise until just before midnight (daylight saving time) in most of Australia, so you will still have to disturb your sleep for this one. 

Australians should see a meteor every two to three minutes under dark skies in the early morning of the 14th, between 1:00 am and 4:00 am local daylight saving time. You can find predictions for your local site at the meteor flux estimator (choose 4 Geminids and date 14-15 December, don't forget to change the date to 2017). I have alos made a table for major citiess below.

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.
You can follow the progress of the shower at the IMO Geminids Live page.


At 1.00 am in the morning AEDST (midnight, AEST) Castor (alpha Geminorum) is about two hand-spans above the horizon and 10 hand-spans to the right of due north. Pollux, the other twin, is less than a hand-span to the right again. The radiant is just below Pollux.

When you get up, allow at least 5 minutes for your eyes to adjust and become dark adapted (even if you have stumbled out of bed in the dark, here's some hints on dark adaption of your eyes so you can see meteors better) and be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession (a meteor every three minutes is an average, they won't turn up like a ticking clock but more or less randomly).

Predicted meteor rates for selected towns

TownMorning December 13 Morning December 14Morning December 15
Adelaide9 meteors/hr22 meteors/hr15 meteors/hr
Brisbane11 meteors/hr27 meteors/hr21 meteors/hr
Darwin16 meteors/hr41 meteors/hr27 meteors/hr
Perth11 meteors/hr26 meteors/hr15 meteors/hr
Melbourne8 meteors/hr19 meteors/hr13 meteors/hr
Hobart6 meteors/hr14 meteors/hr10 meteors/hr

Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with street lights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an insalubrious park for example). While the radiant is where the meteors appear to originate from, most of the meteors will be seen away from the radiant, so don't fixate on the radiant, but keep your eye on a broad swath of sky roughly centred just above the radiant (as the radiant doesn't rise very high, looking exactly at the radiant will mean you miss some higher up).

A lawn chair or something similar will make your observing comfortable (or a picnic rug spread on the ground and a nice pillow), and having a Thermos of hot coffee, tea or chocolate to swig while watching will increase your comfort. Despite it being summer, make sure you have a jumper or something as the night can still get cold

Guides to taking meteor photos are here and here.

As well, Orion and the Hyades will be visible and bright Jupiter (and less bright Mars) will be nearby, rising an hour before sunrise. So it will be a quite nice morning for sky watching. Keep an eye out for satellites!

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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The Sky This Week - Thursday November 30 to Thursday December 7

The Full Moon is Monday, December 4. This is a perigee ("super") Moon. On the 3rd the nearly full Moon is in the head of Taurus the Bull.  Mercury and Saturn sink into the twilight.  Jupiter is now prominent in the morning sky and is heading towards the bright star alpha2 Librae. Mars is relatively easy to see and starts the week close to the bright Spica but soon leaves it behind as it heads towards Jupiter.

The Full Moon is Monday, December 4. This is a perigee ("super") Moon. As the Moon is closest to the Earth it is bigger and brighter than normal Full Moons, however as it will be only be around 14% larger and 30% brighter than an apogee Full Moon, you will probably need a telescope and photographic evidence to see the difference. For more detail and photography links see my Super Moon page.

Evening sky on Saturday December 2 looking west as seen from Adelaide at 21:00 ACDST  (45 minutes after sunset). Mercury is low above the horizon and is close to  Saturn.

Similar views will be seen elsewhere in Australia at the equivalent local time (45 minutes after sunset). (click to embiggen).

Mercury is visible in early evening and is above the western horizon in the late twilight. Mercury and Saturn are now falling back into the twilight. Mercury is visible after civil twilight, but you need a clear level horizon to see it at its best.

Saturn is visible low in the early evening twilight near Mercury and will be effectively lost to view by the end of the week.

Morning sky on  Saturday December 2 looking east as seen from Adelaide at 5:26 ACDST (30 minutes before sunrise). Venus is lost in the twilight. Jupiter is prominent and Mars can be seen close to the bright star Spica.

 Similar views will be seen throughout Australia at the equivalent local time (that is 30 minutes before sunrise, click to embiggen).

Venus  is lost in the twilight.

Jupiter climbs higher in the morning twilight and is now becoming prominent.

 Mars is climbing higher the twilight, and is is coming closer to the bright star spica. The pair are closest on the 30th.



Evening sky on Saturday December 2 looking east as seen from Adelaide at 22:00 ACDST. The Moon is in the head of Taurus the Bull. Similar views will be seen elsewhere at equivalent local times. (click to embiggen)

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.

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, November 21, 2017

 

The Sky This Week - Thursday November 23 to Thursday November 30

The First Quarter Moon is Monday, November 27.  Mercury climbs higher in the evening twilight and is closest to Saturn low in the early evening sky on the 28th.  Venus is lost in  the morning twilight while Jupiter is now prominent. Mars is close to the bright star Spica on the 30th.

The First Quarter Moon is Monday, November 27.

Evening sky on Tuesday November 28 looking north-west as seen from Adelaide at 20:55 ACDST  (45 minutes after sunset). Mercury is low above the horizon and is closest to  Saturn.

Similar views will be seen elsewhere in Australia at the equivalent local time (45 minutes after sunset). (click to embiggen).

Mercury is visible in early evening and is above the western horizon in the late twilight. Mercury is quite prominent, and is well worth watching as it rises into the evening sky towards Saturn. On the 28th Mercury and Saturn are at their closest. Mercury is visible well after civil twilight, but you need a clear level horizon to see it at its best.

Saturn is visible low in the early evening twilight setting around 9:40 pm local time. Saturn is no longer a viable telescopic target, being too close to the horizon when the sky is fully dark. Saturn continues to sink into the western evening skies as the week progresses but the approach of Mercury will be interesting to watch. 

The constellation of Scorpio is no longer a good guide to finding Saturn and Mercury any more as Antares is lost in the twilight. Both Mercury and Saturn will be obvious above the south western sky long before the fainter stars in the tail are visible.

Morning sky on  Thursday November 30 looking east as seen from Adelaide at 5:26 ACDST (30 minutes before sunrise). Venus is lost in the twilight. Jupiter is prominent and Mars can be seen close to the bright star Spica.

 Similar views will be seen throughout Australia at the equivalent local time (that is 30 minutes before sunrise, click to embiggen).

Venus  is lost in the twilight.

Jupiter climbs higher in the morning twilight and is now becoming prominent.

 Mars is climbing higher the twilight, and is is coming closer to the bright star spica. The pair are closest on the 30th.

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.

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, November 20, 2017

 

Astrophiz Podcast 47 (Sqaure Kilometer Array edition) is Out!

Astrophiz Podcast 47 is out now.

This episode we are speaking with Dr Phil Edwards, Australia’s SKA leader from the CSIRO. He is now Head of ATNF (Australia Telescope National Facility) Science at the CSIRO and SKA Project Scientist.

Phil is originally from South Australia and did his BSc, BScHons and PhD at the University of Adelaide, and he gives some great insights on the often meandering career paths of scientists.

As well as giving us an inside look at the Square Kilometre Array (the SKA), he explains about a recent discovery of high energy neutrinos from beyond our galaxy. He is one of the Australian members of an international team that follows up some neutrino detections that came about by bugging a cubic kilometre of ice down in the Antarctica. This is big science, using monstrous detectors looking for the tiniest particles that give us new understandings of our cosmos.

For observers and astrophotographers, I tells you what when and where to look for objects in the morning and evening skies, including current meteor showers.

You can follow me  @ianfmusgrave on Twitter and southern skywatch on facebook.

In the News: A newly published paper that casts further light on those mysterious FRBs

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