Astroblog

Partial Eclipse as seen from Adelaide at maximum eclipse, 8:18 am ACST. Simulated in Celestia.	Partial Eclipse as seen from Cairns at maximum eclipse, 8:48 am AEST.
Partial Eclipse as seen from Hobart at maximum eclipse, 8:59 am AEST.	Partial Eclipse as seen from Perth at just after sunrise, 6:58 am AWST.

On the morning of May 10, there will be an annular Solar eclipse. In an annular eclipse the Moon does not completely cover the Sun, and the Sun forms a thin ring around the Moon at maximum eclipse depth.

The annular eclipse will be seen from a thin strip in WA, the Northern Territory and remote far north Queensland. Everywhere else will see a partial eclipse of varying depth, the north-east coast of Australia having the best views. The eclipse starts shortly after sunrise. In places along the annular eclipse path, such as Tennant Creek (NT) and Musgrave Roadhouse (QLD), viewers will see a thin rim of Sun around the moon.

Elsewhere viewers will see between 13% (Hobart) - 83% (Cairns) of the Sun covered by the Moon (scroll down for local times for several Australian locations). A diagram showing eclipse times in Universal Time is here, and an interactive map of the path is here. Click on the map for local timings of the eclipse.

UPDATE: In addition to the local Australian times below (scroll down) I've created a table of local times for PNG and the pacific regions. That link also has a link to the SLOOH web cast and a live viewing in Tasmania. New Zealand and other places still have to make do with the dynamic Google Eclipse Map (click on the map and the times of the eclipse will pop up) or the hard copy table (all in UT).

Do NOT look directly at the Sun! Do not use so called filters. Over exposed film, smoked glass, CD's, chip packets etc. used as filters are NOT, repeat NOT safe. Only special solar-rated viewing spectacles from astronomical suppliers should be used (for one example see here), they may cost a bit, but your eyesight is without price. Never use eyepiece filters for telescopes. These can crack at inopportune times and destroy your eyesight. In the annular eclipse path, as there is always some of the solar disk visible, at no time is it safe to view the eclipse with the unaided eye.

The easiest and cheapest way to observe this event is by making a pinhole in a stiff square of cardboard and projecting the image of the Sun onto a flat surface. You are basically making a simple pinhole camera, which will reveal the changes to the Suns outline quite satisfactorily. A card with a 1 mm hole should be projected onto a surface (eg white paper, or a white wall) about 20 cm away, a 5 mm hole should be projected onto a surface 1 to 1.5 meters away.

You need to create a reasonable sized image, so you need a fair distance between the pinhole and the surface you project the image on. This will mean the image is going to be fairly dim, so you also need some sort of sun shield to keep in image in shadow. I use the longest available postpac postal tube, with alfoil over the top (and the pinhole in the alfoil), and wide ring of stiff cardboard to ensure that the image of the sun is projected into a dark area. This link will show you several methods to make pinhole projection systems.

You can also use binocular and telescopic projection systems. This link will show you how to make safe solar viewing and telescope projection systems. Here is my step by step guide to making a binocular projection system, and a guide to aiming your binoculars or telescope when you can't actually look at the Sun. And this is the projection system I use with my refractor telescope.

Remember, do NOT look directly at the Sun, as irreparable eye damage or blindness can occur (see this video for a graphic demonstration).

City	Eclipse Start	Mid Eclipse	Eclipse End	% Sun covered
Adelaide (ACST)	7:09 am	8:15 am	9:22 am	38
Alice Springs (ACST)	below horizon	8:07 am	9:31 am	79
Brisbane (AEST)	7:41 am	8:58 am	10:28 am	40
Cairns (AEST)	7:28 am	8:49 am	10:27 am	83
Canberra (AEST)	7:50 am	8:55 am	10:10 am	26
Darwin (ACST)	below horizon	8:07 am	9:28 am	68
Hobart (AEST)	8:06 am	8:59 am	9:57 am	13
Melbourne (AEST)	7:50 am	8:52 am	10:02 am	25
Musgrave Roadhouse (AEST)	7:26 am	8:47 am	9:29 am	95 Annular Eclipse
Perth (AWST)	below horizon	below horizon	7:45 am	-
Rockhampton (AEST)	7:34 am	8:54 am	10:30 am	56
Sydney (AEST)	7:50 am	8:57 am	10:14 am	27
Tennant Creek (ACST)	6:57 am	8:07 am	9:28 am	95 Annular Eclipse
Townsville (AEST)	7:29 am	8:49 am	9:28 am	74

Labels: eclipse, solar

Correspondent Kurt Ams sends in this beautiful image of Alpha1 (Zubenelgenubi) and Alpha2 Librae just after they reappeared from the dark limb of the Moon.

The image was taken in Sydeny at 21:15, April 26. Click to embiggen ((c) Kurt Ams, remember to play nice and ask permission if you want to use this image)

Labels: Moon, Occultation

Carnival of Space #299 is now up at Tranquillity Base. There's meteors, the partial eclipse of the Moon, Saturn, cometary water in Jupiter's atmosphere, the Lunar crust and lots, lots more. Slip on over and have a read.

Labels: carnival of space

Location of Saturn at midnight on the 28th of April looking north from Adelaide. Similar views will be seen elsewhere in Australia at equivalent local times. Click to embiggen.

Saturn is at opposition on Sunday April 28. At this time it is biggest and brightest as seen from Earth.

Don't worry if you don't observe it on the 28th. Unlike Mars, which changes significantly in size and brightness between opposition and the months after, Saturn remains relatively big and bright for a long time after opposition.

At opposition Saturn is magnitude 0.1 and  42.6 seconds of arc wide (or rather, its rings are), while a month later it is magnitude 0.3 and 41.9 seconds of arc wide. For Mars, at the record 2003 opposition, Mars went in one month from magnitude -2.9 and 25 arc seconds across to -2.2 an 21 arc seconds across. For comparison, the Moon is 31 arc minutes wide.

Simulation of  the telescopic view of Saturn at midnight on April 28.

The main impact of the opposition is that now Saturn will be high enough above the horizon for good telescopic views at convenient times. Saturn (and other planets) need to be reasonably high above the horizon of atmospheric turbulence will make seeing the features of the planet quite difficult.

Although Saturn is a magnificent object, most people aren't willing to stay up to 1or 2 am to see it. Now that we are at opposition, although the best views are around midnight, good viewing can be had from 9 pm on.

While Saturn is not particularly bright, it is still the brightest object above the north-eastern to northern horizons. It's golden colour also distinguishes it from white Spica, orange Arcturus and red Aldebaran; the other bright objects in the north-eastern to northern sky near Saturn.  In binoculars Staurn is a distinct oval, although you can't distinguish the rings. Unlike Jupiter, Saturn's Moons are not bright enough to see in binoculars, not even Titan.

In even small telescopes though, Saturn and its rings floating in space is magnificent. Titan can bee seen too to reslly see the banding on Saturn or the Cassini division and the smaller Moons requires a more serious telescope. But even in my 50 mm refrector the panet and its rings float like a jewel on the velvet of space.

If you are watching Saturn with a telescope, set the scope up at least a half hour before hand so the the telescope can cool down and minise thermal turbulence inside the telescope. 

If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums.

Labels: Opposition, Saturn

Alpha Librae (Zubenelgenubi) at 7:26 pm ACST, just before the serious clouds rolled in. Image taken with a Canon IXUS at 400 ASA, auto exposure timing , and infinity to infinity focussing thorough a 4" Newtonian and 25 mm eyepiece.	Emergence of Zubenelgenubi at 8:32 (well, it had emerged earlier, but this was my first image). You may need to embiggen the picture to see the faint blob near the bottom.
A clearer image of Zubenelgenubi as it pulls away from the Moon.	A slightly over exposed image showing Zubenelgenubi and it's partner, Alpha2 Librae (again, you may need to click to embiggen to see the faint star near the bottom right).

Wouldn't you believe it. Today's occultation was a mirror image of this mornings eclipse. A beautiful afternoon of blue sky, and as soon as it came time for Moonrise, cloud.

Also, we had folks over for dinner, and the boys had friends over too. so I wasn't paying as much attention as I could have, but ingress of  Zubenelgenubi and its dimmer companion Alpha2 Librae was totaly clouded out for me. I did get a couple of shots before the cloud made things impossible.

The cloud had thinned to a reasonable level by the time of egress. Due to being distracted by dinner guests and visiting boys I wasn't paying as much attention to the egress orientation as I should have. So I spent a good 4 minytes or so photographing a bright peak on the edge of the Moon, under the impression I was imaging Zubenelgenubi.

I wasn't, frustratingly it was just off the edge of the frame.

Still I did get some good shots of it near the edge of the Moon, and one decent shot of bot Zubenelgenubi and Alpha2 Librae together. Not a bad evenings work (and had a great dinner with friends as well).

Labels: Moon, Occultation

The solar wind flowing from a large coronal hole has intensified and the IPS has issued a geomagnetic alert. Minor storms are predicted for high latitudes (Tasmania, Southern New Zealand, Australian Antarctic Territories) tonight and unsettled conditions the day after (Friday 27th and Saturday 27th). Aurora can strike any time, although the best time to look to the south around local midnight.

However, the bright, just past full moon will significantly interfere with seeing any aurora, and dark sky sites have the best chance of seeing anything. IPS notice below.

A low latitude coronal hole effects in progress. Unsettled to
Active levels are expected 26-27 April. Minor storm levels still
possible.

INCREASED GEOMAGNETIC ACTIVITY EXPECTED
DUE TO CORONAL HOLE HIGH SPEED WIND STREAM
FROM 26-27 APRIL 2013
_____________________________________________________________

GEOMAGNETIC ACTIVITY FORECAST
26 Apr:  Active to Minor Storm
27 Apr:  Unsettled to active.

Labels: aurora

Dawn Service, Semaphore foreshore, ANZAC Day 2013.

I normally alternate between the dawn services at Largs and Semaphore. This year was Semaphore's turn, and I cycled down under a cloudy sky with the setting Moon hidden under a band of cloud.

This year there was more people than ever. A huge increase over the last time I was here, despite the clod an threatening rain. With added St' Johns amulance vans, a coffee tent and the rotary cooking breakfast it was a somewhat lighter atmosphere than last time. The rotary and coffee van were never there before.

The service was goo, and the Salvation Army Children's Choir were beautiful. 

Labels: home life, miscellaneous

The Moon shortly after eclipse started at 5:08 am ACST. Image taken with Canon IXUS at ASA 400 on auto exposure through a 4" Newtonian, and 25 mm eyepiece, infinity to infinity focussing. South pole is already darkening (click to embiggen).	Moon at 5:11 am, darkness is encroaching.
Moon at 5:14 diffuse cloud messing up the brightness	Moon at 5:21 am, last decent shot, thin cloud messing up exposure.

Before heading to bed in preparation for the mornings partial eclipse, I checked the sky. After the cloud of the morning the sky was brilliantly clear. Arising at 4:45 am this morning the sky was still clear with a few fluffy clouds about, perfect!

Of course, as soon as I had the telescope set up (with my little 4" Newtonian for easy of use), the clouds started coming over. I started imaging when the bottom of the Moon was already visibly dark from the penumbra, so I don't have a good "start" comparison image (hey getting up at 4:45 am after a 5 am rise for the Dawn Service the previous day was pretty good I thought). Have a look at the "before" image from last years penumbra eclipse for an idea of what the "before" should have been, a nice, more even brightness.

As the eclipse progress the clouds started coming more frequently, getting darker and with fewer gaps.  With the unaided eye the darkening was obvious, although confined to a thin sliver at the Moons south.

The problem I had was that the Canon does not have an fixed time setting below 1 second, far too long for exposures with my unguided Newtonina, and over exposing everything except perhaps ASA10. I I had to stick with autoexposure Which is fine if there are no clouds about, but for the latter images cloud was always over the Moon, messing up the exposure so that the darkening on the southern limb is less than what I was seening with my eyes.

9 minutes before maximum eclipse a thick band of cloud came over and squatted there  until past maximum . At this stage I packed up and went inside.

After packing up, putting telescope away and so on. I went out side for one last check, and the Moon appeared through a sucker hole, as if to mock me. The darkened south pole was an obvious notch on the base of the Moon.

Labels: eclipse, Moon, partial

The morning sky facing north-east in Adelaide on April 26 at 19:00 pm ACST showing the full Moon just about to cover Alpha Librae,(the bright dot just on the edge of the Moon). (similar views will be seen from other locations at a similar local time eg 20:01 pm AEST Brisbane.

The inset shows a telescopic view of the Moon at 19:30 ACST, with alpha1 (the dim star) and alpha2 Librae about to go behind the Moon (click to embiggen).

April 26 is a fairly busy day, astronomy wise. in the morning, we have a partial eclipse of the Moon, and in the evening  the waning Moon passes in front of the bright star Alpha Librae (which rejoices in the name Zubenelgenubi) in the constellation of the Libra the balance.

Alpha Librae is a double star with both stars visible to the unaided eye (magnitude 3 and 5 components). The times shown in the table below are for the bright component of the double star, but the 5th magnitude star disappears and reappears 5 minutes earlier.

With the Moon Full, this event is really best seen with binoculars or a small telescope (especially for the disappearance of the star on the bright limb of the Moon). If you have a tripod or other stand for your binoculars, it will be much easier to observe. Set up about half an hour before the occultation to watch the star disappear (so you are not mucking around with equipment at the last moment).

City	Disappears behind bright limb	Reappears from dark limb
Australia
Adelaide (ACST)	19:41	20:30
Brisbane (AEST)	20:01	21:05
Canberra (AEST)	20:12	21:11
Darwin (ACST)	--	20:03
Alice Springs (ACST)	19:18	20:14
Townsville (AEST)	19:58	20:47
Hobart (AEST)	20:29	21:14
Melbourne (AEST)	20:17	21:08
Perth (AWST)	--	18:48
Sydney (AEST)	20:10	21:12

Labels: Moon, Occultation

The Full Moon is Friday April 26. There is a partial eclipse of the Moon on the morning of the 26th, and an occultation in the evening. Jupiter is low in the early evening sky. Saturn is at opposition on the 28th, when it is biggest and brightest as seen from Earth. Mercury is low in the morning skies. Comet C/2012 F6 Lemmon is high in the morning skies.

Western horizon as seen from Adelaide at 5:30 am ACST on April 26. The Moon is near mid-eclipse at this time. The illustration makes it look worse than it will be, there will be a definite dark "chip" seen at the Moon's south pole, and the southern half of the Moon will be subtly darker than the North.

On the early morning of 26 April there there be a partial eclipse of the Moon. This is a very poor eclipse, with only a small bite take out of the Moon's northern edge. It is still worth getting up for though.

WA has the best view, while the east coast sees the eclipse in various stages of twilight, and may be quite difficult to see.

The eclipse starts at  5:52 am AEST (nautical twilight twilight), 5:22 am ACST and 3:52 am AWST.

Mid-eclipse is 6:07 am AEST (deep in twilight), 5:37 am ACST and 4:07 am AWST.

See here for a map and contact timings in UT for sites outside Australia

Sky on Friday April 26 looking east as seen from Adelaide at 21:00 local time in South Australia. The left inset shows a telescopic view of Saturn at this time. The right inset shows alpha Librae reappearing from occultation at 20:30. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

The Full Moon is Friday April 26.

The waning Moon passes in front of the bright star Alpha Librae (which rejoices in the name Zubenelgenubi) in the constellation of the Libra the balance on the early evening of April 26. Alpha Librae is a double star with both stars visible to the unaided eye (magnitude 3 and 5 components). The times shown in the table in the link below are for the bright component of the double star, but the 5th magnitude star disappears and reappears 5 minutes earlier.  Timings of the disappearance and reappearance of the stars can be found here.

Saturn is now easily visible above the eastern horizon before midnight in the constellation of Libra. Saturn climbs higher in the evening sky during the week, becoming easier to see.

Opposition (when Saturn is biggest and brightest as seen from Earth) is on April 28, Saturn is a worthwhile evening target for telescopes of any size. The sight of this ringed world is always amazing.

Morning sky on Sunday April 28 looking east as seen from Adelaide at 5:45 am local time in South Australia showing Mercury, Uranus and comet Lemmon. The inset shows a binocular view of Mercury and Uranus at this time. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Mercury  is still prominent low in the morning skies this week, although it is sinking towards the horizon. It is now difficult to see low above the eastern twilight sky 3/4 of an hour before dawn.

Comet C/2012 F6 Lemmon is in the morning skies above Mercury. At around magnitude 6, you will need binoculars to see it clearly. The comet progressively moves higher and becomes dimmer as the week passes.

Bright white Venus  is lost in the twilight.

Mars is lost in the twilight.

Evening sky looking west as seen from Adelaide at 18:30 pm local time on Saturday April 27. The inset shows Jupiter's Moons at this time. Similar views will be seen elsewhere at the equivalent local times indicated here.  Click to embiggen.

Jupiter is visible low in the early evening, and is the brightest object in the early evening sky.

Jupiter is  low in the western early evening sky, being quite visible in the twilight.  Jupiter is moving away from the Hyades, but is still near the red star Aldebaran.

Jupiter, Aldebaran and the red star Betelgeuse in Orion form a long triangle in the sky. With the Pleiades cluster and the constellation of Orion close by, this is a beautiful sight.

Jupiter is setting progressively earlier, by 7:50 pm local time, so the giant world is harder to see in a telescope. Jupiters' Moons are easily seen in binoculars, and can be followed from night to night changing position, but with a narrow window between twilight and Jupiter setting, you won't have time to see much action..

There are lots of interesting things in the sky to view with a telescope. Especially with Saturn so prominent in the sky.  If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums. Especially during the school holidays.

Printable PDF maps of the Eastern sky at 10 pm AEST, Western sky at 10 pmAEST. For further details and more information on what's up in the sky, see Southern Skywatch.

Cloud cover predictions can be found at SkippySky.

Labels: weekly sky

Comet C/2012 F6 Lemmon as seen in the STEREO H2A imager on April 19, 2013. Image processed in ImageJ.

While all eyes have been on C/2011 L4 PanSTARRS (and rightly so, while small it has been magnificent), comet C/2012 F6 Lemmon has been quietly chugging away in the background.

While C/2011 L4 PanSTARRS has had it's moment in the STEREO imagers, Lemmon has not, until yet.

On April 17 the comet began to enter the field of view of the H2A camera, and is crossing the bottom half of the camera quite nicely. It's a bit hard to see in the image above, where I have boosted the brightness a bit to bring out the tail, but the comet has quite a long and dynamic tail.

For the animation below I stacked 29 images from 17 April to 19 April in ImageJ, then inverted the image and tried to maximise the brightness and contrast to get the tail  as visible as possible. The stack was then exported as an AVI. While not the best, if you look closely you can see some tail dynamics.

Labels: C/2012 F6, comet, Stereo comet astronomy, Stereo Satellite

Carnival of Space #297 and #298 are now up at Dear Astronomer and Everyday Spacer respectively (sorry got caught up in stuff and forgot to post about #287). There's heaps of good stuff, capturing asteriods, fast fusion drives, naming exoplanets, giant telescopes, what if we had no Moon and lots, lots more. Zap on over and have a read.

Labels: carnival of space

The Kepler-62 system, simulated in Celestia, click to embiggen.	The view looking from the Super-Earth Kepler-62e, looking to the Inner solar system and the Water World 62f, the smallest world currently known in a habitable zone, beyond. Simulated in Celestia, click to embiggen.

The plethora of exoplanets pouring out of the Kepler mission keeps amazing me. As you know, I'm quite an exoplanet fan, but I just can't keep up with the discoveries. As of today there are 866 confirmed exoplanets, and Kepler has 2,740 (yes, you read that right) planetary candidates that need to be worked through and confirmed.

The latest batch are the systems  Kepler-62 and Kepler -69. Kepler-62 hosts 5 planets, and Kepler-69 two. Gone are the days when exoplanets were all Super-Jupiters or Jupiter sized, we are picking up lots of  Terrestrial sized planets now (even if they are mostly Super-Earths).

Importantly, both these systems host planets in their respective habitable zones. Kepler-62 has two planets in its habitable zone and Kepler-69 has one. Kepler 62-f is the smallest known world in a habitable zone, and Kepler 69-c is the smallest planet in the habitable zone of a sun-like star (Kepler 62 is substantially smaller and cooler than the Sun).

While these worlds are similar in size to Earth (although bigger), it looks like the Kepler 62 planets are Water Worlds, occupied by a global ocean rather than having continents like Earth.

As well, Kepler-62-c is the smallest exoplanet found yet, about the size of Mars (but much hotter).

For more detailed discussion of the meaning of these exoplanets see the Kepler press release (with link to the published paper) and this Australian ABC report. Nancy Atkinson at Universe today has a nice image and animation roundup of the new systems.

Me, what can I contribute? As usual I've made Celestia files. I've just done the Kepler-62 system, I'll do Kepler-69 later. One for the star (which isn't in the default files) and one for the planet.

Copy the data here to plain text files (Kepler62.stc and Kepler62Planets.ssc), copy both of the files to the Celestia extras folder. The star is around 1200 lightyears away in Lyra, so in the Celestia star browser, you will have to show around 500 stars to see Kepler-62 in the list.
I'll have to update my Celestia Exoplanet Tour as well.

===============Kepler62.stc======================================
#Kepler survey

"Kepler-62:2MASS J18525105+4520595:KIC 9002278"
{
RA 283.2125
Dec 45.3497
Distance 1200 # light years from published data
SpectralType "K2V"
AppMag 14.0
}
=======================================================
==================Kepler62Planets.ssc============================
"b" "Kepler-62"

# Neptune like world?

{
    Texture "exo-class4.*"
    NightTexture "exo-class4night.*"


Mass 9 # M.sin(i) = 9 Earth
Radius 8355.18 # 1.31 Earth radi, from paper

#InfoURL "http://en.wikipedia.org/wiki/Kepler-62b"

EllipticalOrbit {
Period 0.015646374
SemiMajorAxis 0.0553
Eccentricity 0
ArgOfPericenter 267 #guess
Inclination 89.2
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Kepler-62/b"
{
    Texture "extrasolar-lok.*"

}

"c" "Kepler-62"

# Mercury-Like world

{
    Texture "mercury.*"


Mass 4 # M.sin(i) = 4 Earth
Radius 3444.12 # 0.54 Earth radi, from paper

#InfoURL "http://en.wikipedia.org/wiki/Kepler-62c"

EllipticalOrbit {
Period 0.034062959
SemiMajorAxis 0.0929
Eccentricity 0.0
ArgOfPericenter 267 #guess
Inclination 89.7
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Kepler-62/c"
{
Texture "extrasolar-lok.*"
}

"d" "Kepler-62"

# Neptune like world

{
    Texture "exo-class4.*"
    NightTexture "exo-class4night.*"


Mass 14 # M.sin(i) = 14 Earth
Radius 12437.1 # 1.95 Earth radi, from paper

#InfoURL "http://en.wikipedia.org/wiki/Kepler-62d"

EllipticalOrbit {
Period 0.049729669
SemiMajorAxis 0.120
Eccentricity 0.0
ArgOfPericenter 267 #guess
Inclination 89.7
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Kepler-62/d"
{
    Texture "extrasolar-lok.*"
}

"e" "Kepler-62"

# earth like, possibly water world

{
    Texture "exo-class4.*"
    NightTexture "exo-class4night.*"


Mass 36 # M.sin(i) = 36 Earth, upper limit of theoretical range
Radius 10268.58 # 1.61 Earth radi, from paper

#InfoURL "http://en.wikipedia.org/wiki/Kepler-62e"

EllipticalOrbit {
Period 0.335072935
SemiMajorAxis 0.427
Eccentricity 0.0
ArgOfPericenter 267 #guess
Inclination 89.98
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Kepler-62/e"
{
Texture "venussurface.*"
OverlayTexture "ganymede-lok-mask.png"
}

"f" "Kepler-62"

# earth like world

{
    Texture "ganymede.*"
    # Using Ganymede as it may be giant ice world
        # NightTexture "gasgiantnight.jpg"


Mass 35 # M.sin(i) = 35 Earth theoretical maximum
Radius 8992.98 # 1.41 Earth radi, from paper

#InfoURL "http://en.wikipedia.org/wiki/Kepler-62f"

EllipticalOrbit {
Period 0.731790854
SemiMajorAxis 0.718
Eccentricity 0.0
ArgOfPericenter 267 #guess
Inclination 89.9
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Kepler-62/f"
{
    Texture "ganymede.*"
    OverlayTexture "ganymede-lok-mask.png"
}

==============================================================

Labels: celestia, exoplanet, extrasolar planet

Western horizon as seen from Adelaide at 5:30 am ACST on April 26. The Moon is near mid-eclipse at this time. The illustration makes it look worse than it will be, there will be a definite dark "chip" seen at the Moon's south pole, and the southern half of the Moon will be subtly darker than the North.

On the early morning of 26 April there there be a partial eclipse of the Moon. This is a very poor eclipse, with only a small bite take out of the Moon's northern edge. It is still worth getting up for though.

WA has the best view, while the east coast sees the eclipse in various stages of twilight, and may be quite difficult to see.

The eclipse starts at  5:52 am AEST (nautical twilight twilight), 5:22 am ACST and 3:52 am AWST.

Mid-eclipse is 6:07 am AEST (deep in twilight), 5:37 am ACST and 4:07 am AWST.

See here for a map and contact timings in UT for sites outside Australia

Labels: eclipse, Moon

Taking SmallestOne on an outing, we saw a display of chocolate art.

Labels: homelife

Track of comet C/2012 S1 ISON from 14 November 2013 to 20 November 2013 an hour before Sunrise. The yellow crosses mark the position of the comet on successive days starting from November 14. It may  be as bright as magnitude 4 (about as bright as epsilon Crucis, the 5th brightest star in the Southern Cross). on the 14th. On the 18th, when the comet is around magnitude 3 (maybe), the comet is just over a hand-span (7 degrees) above the horizon an hour before Sunrise (click image to embiggen).	Track of comet C/2012 S1 ISON from 20 November 2013 to 28 November 2013 half an hour before Sunrise. The comet will brighten from around magnitude 2 (about as bright as Gacrux, the third brightest star in the Southern cross) to somewhere around magnitude -4 (as bright as Venus). (click image to embiggen)
On the 28th the comet is very close to the sun, and very bright. It's magnitude may be anywhere between -4 (as bright as Venus) and -8 (as bright as the two day old Moon). But at this time it will be only 3 degrees from the Sun. This zoomed in image exaggerates the distance rom the Sun, it will be more like the current position of Venus  in the illustration below (click image to embiggen)	When the Sun rises in Australia on the 29th, the comet will be somewhere between magnitude -8 and -12. At half an hour after Sunrise the comet should be high enough off above the horizon to see, but it is only a degree (a finger-width) from the Sun, and so will be very difficult to see. You will of course need a very robust object to block out the sun, and a bit of practise at seeing objects near the Sun.

Comet C/2012 S1 ISON has been dubbed "the comet of the Century", should it survive its close approach and not disintegrate ISON promises to be a bright comet and will hopefully develop a spectacular tail.

While the comet will be bright, reports the it may be "as bright as the full Moon" do not make clear that the comet will be very hard to see because of its closeness to the Sun.

Working out just how bright comet ISON will get is difficult. New comets dropping in from the depths of the Oort cloud can behave somewhat differently to the more familiar short period comets. New comets often rapidly brighten, then slow down or pause their brightness increase as they get closer to the Sun. This makes predicting the comets brightness near closest approach to the Sun (perihelion) more difficult.

Current predictions for comet ISON's brightness at closest approach run from around -12 (almost as bright as the full Moon) to around -8 (as bright as the two day old Moon). While most popular articles on the comet have been generally careful to point out the uncertainties in the brightness evolution of the comet (and whether it will survive at all), they have been less clear about what the brightness means.

They often give the impression you will be able to see the comet at it's brightest after sunset (no, you can't) or well before or after perihelion. The comet will only be at its brightest for a few hours, and bright enough to (possibly) see in daylight for around two days.

Can you see Venus? It's in this picture. Even at magnitude -3.9 and 3 degrees (around 3 finger-widths) from the sun, Venus is very difficult to see. 

In fact, even at it's brightest the comet will be very difficult to see.

While at its peak it will be brighter than Venus, it will also be very close to the Sun. At closest approach the comet will be around a degree from the Sun. That's about a finger-width from the Sun, buried in the glare around the Sun. If the comet is -8 or brighter, and you have clear, cloud free and dust free conditions, you may be able to see it if you follow special precautions (see below).

I was (just) able to see comet C/2006 P1 McNaught in the daylight, when it was about magnitude -5, and 6 degrees from the Sun.

To give you an idea of how difficult it may be to see comet ISON at it's brightest, Venus is currently magnitude -3.9, bright enough to be visible in the daylight when some distance from the Sun. Now, spotting Venus in the daylight is a hobby of mine, but Venus is currently around 3 degrees from the Sun.  Although I am reasonably adept at seeing Venus in the daylight when it is 10 degrees or more from the Sun, I am utterly unable to see it at the moment, when it is so close (see image above).

If the best brightness prediction for comet ISON come true (-12 at maximum and around -8 when the comet is 3 degrees from the Sun), it will be easier to see, but not very easy. If the comet is dimmer (-8 at maximum and -4 at 3 degrees from the Sun) it will be quite difficult to see.

Now, before attempting to view ISON in the daylight, remember that looking directly at the Sun can damage your eyes. You need to be particularly careful because the comet is so close to the Sun. Make sure the Sun is hidden behind something solid like a building or a wall when you are looking for Venus, not trees or your hand. Exposing your eyes directly to the glare of the Sun can be very dangerous and you could potentially lose your sight. Indeed, it may be best not to try at all unless you have some practise with observing Venus beforehand. If you are at all unsure, don't do it, your eyesight is far too important.

When the comet is near its peak, it's best to look when the Sun is low and the sky is less bright (early morning or late afternoon, early morning is best for Australians). Also dust, humidity and thin cloud all conspire to make the region around the sun brighter and the comet much harder to see. You will need a clear sky with good transparency to see the comet. Chose your viewing location so that the Sun will be hidden well behind some solid object at all of your projected viewing times.

Venus's location at midday, 18 April ACST as seen from Adelaide looking north. Venus can be a good training target to practise for comet ISON.

If you have been following the comet before its closest approach, you will have a good idea of where the comet is in relation to the Sun. Otherwise you need a chart of the comets location to help you look in the right location.

It may be difficult to see the comet directly, you may need to use averted vision, where you flick your eyes away form the location of the comet (your eyes are more sensitive away from the centre of vision). You may also need to have a couple of object lie poles or antenna near where you expect the comet to be to give you a visual reference.

The title of this post is "practise now". Obviously, given the short time the comet will be (potentially) bright enough to see in daylight it would be good tor try an practise seeing objects in daylight beforehand. The obvious object is Venus, currently (as I said before) -3.9 magnitude and 3 degrees to the west of the Sun (see diagram above). If you can see Venus in the daylight under current conditions, you will be able to pick up the comet.

All the comments about seeing the comet applies to Venus (blocking with solid object, protecting your eyes, using averted vision). So find a solid wall, block out the Sun and see if you can see Venus.You may need several attempts under the best sky conditions to pick it up. At the very least you will gain an appreciation of the difficulty of seeing comet ISON at its brightest.

After November the 29th the comet is not visible from Australia. If we are lucky the comet will not disintegrate during or shortly after its passage of the Sun (like comet Lovejoy did), and the northern hemisphere will see a comet with a spectacular tail.

Here's an animation of the comet's approach as seen from Australia, with some commentary. The brightness increase may make more sense in the animation than in the static images.

Labels: C/2012 S1 ISON, comet, Daylight, Daytime, unaided eye

The morning sky looking north as seen from Adelaide at 4:00 am ACST on April 23. The Lyrid radiant is marked with a yellow cross. Similar views will be seen elsewhere at an equivalent local time (click to embiggen). 

There's a series of posts running around Facebook at the moment claiming variously that on the night of 22 April we will have the chance to see "one of the rarest meteor showers" and that during the night "meteors will fall like rain" or "you will be able to see thousands of these falling stars" (ironically, sometimes these statements are sometimes given above the true meteor rate).

These Facebook posts are of course not true. The meteor shower the Facebook posts refer to is the Lyrids, debris of comet C/1861 G1 (Thatcher).  The Lyrids are not rare, they are a reliable shower that occurs every year between April 16- April 25, with the peak this year between 4-15 hrs UT on April 22 (that's between 2pm -April 22 to 1 am 23 April in east coast Australia, but as the radiant doesn't rise until 1 am, the best time to view the Lyrids in Australia is from 4 am on the 23rd). 

The Lyrids will not produce "thousands of falling stars". The predicted ZHR this year is 18 meteors per hour. This means that under ideal conditions, you will see a meteor on average about once every three minutes. This can be as interesting as watching paint dry. Also, while that meteor every three minutes is the average, meteors are like buses, you wait for ages and then a whole bunch turn up.
 
The rate is actually less than the ZHR., ZHR means Zenithal Hourly Rate, the number of meteors you could expect to see if the radiant (the apparent position where the meteors originate) was at the highest point of the sky, under dark sky conditions.

Of course under real conditions the Lyrids radiant will not rise that high for most places, and most places won't have really dark skies. The lower the radaint is, the thicker atmosphere will obscure the fainter meteors, and some of the meteors will start to "burn" below the horizon, so over all you will see fewer.

This is particularly true in Australia, where the radiant is very low to the horizon. In Australia the radiant rises about 1 am local time, but it is not really high enough for there to be any real chance of seeing meteors until around 4 am, when the radiant is between three handspans to four handspans above the horizon (see diagram above). From Australia, at 4 am, under dark sky conditions, we will see between 4 meteors per hour (southern states) to 6 meteors per hour (Northern Territory and QLD).

That's not "meteors falling like rain" (okay, the Lyrids do have occasional outbursts, but the last outburst that was so spectacular was in 1803).

The other factor is the nearly full Moon. This isn't much of an issue in Australia, as the Moon sets before the radiant gets high enough to see any decent number of meteors. But in the northern hemisphere you will need to wait until morning to see a decent number of Lyrids as the Moon washes them out.

 If you want to see what the rates will be like at your area, try the Meteor Flux Estimator.

Choose 6. April Lyrids from the drop down meteor shower Menu, the date (make sure that you set the year to 2013, and your location, most people will have to put in their latitude and longitude (strangely, Adelaide, Brisbane, Darwin and Perth are listed in the drop down menu, but Sydney, Melbourne and Hobart are not) under "other" in the location box.

This will give you a chart of the numbers of meteors per hour you can expect at various times (see image to the left).

The Lyrids won't see meteors falling like rain, but they are a nice reliable shower with some bright meteors, you won't see many, but if you are patient and in the northern hemisphere, you will see some nice ones.

Labels: Meteors

The Last Quarter Moon is Thursday April 18. Jupiter is low in the early evening sky. Saturn becomes more prominent in the late evening sky with opposition next week. The Moon is close to Saturn on the 26th. Mercury is bright low in the morning skies. Comet C/2012 F6 Lemmon is above Mercury in the morning skies. Uranus comes close to Mercury.

Sky on Wednesday April 26 looking east as seen from Adelaide at 20:00 local time in South Australia. The inset shows a telescopic view of Saturn at this time. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

The Last Quarter Moon is Thursday April 18.

Saturn is now easily visible above the eastern horizon before midnight in the constellation of Libra. Saturn climbs higher in the evening sky during the week, becoming easier to see.

With opposition (when Saturn is biggest and brightest as seen from Earth) next week, Saturn is a worthwhile evening target for telescopes of any size. The sight of this ringed world is always amazing.


Morning sky on Sunday April 21 looking east as seen from Adelaide at 5:30 am local time in South Australia showing Mercury, Uranus and comet Lemmon. The inset shows a binocular view of Mercury and Uranus at this time. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Mercury  is still prominent low in the morning skies this week, although it is sinking towards the horizon. It is still easy to see as the brightest object above the eastern twilight sky an hour before dawn.

The planet Uranus is within a binocular field of Mercury from the 20th to the 22nd, being closest on the 21st. The dim world Uranus is actually easily seen in binoculars if you know where to look, and this close pairing with Mercury will make it easy to spot.


Comet C/2012 F6 Lemmon is in the morning skies near Mercury. At around magnitude 6, you will need binoculars to see it clearly. The comet starts the week within a binocular field above Mercury, then progressively moves higher as the week passes.

Bright white Venus  is lost in the twilight.

Mars is lost in the twilight.

Evening sky looking west as seen from Adelaide at 19:00 pm local time on Saturday April 20. The inset shows Jupiter's Moons at this time. Similar views will be seen elsewhere at the equivalent local times indicated here.  Click to embiggen.

Jupiter is visible in the early evening, and is the brightest object in the early evening sky.

Jupiter is prominent low in the western early evening sky, being quite visible in the twilight.  Jupiter is moving away from the Hyades, but is still near the red star Aldebaran.

Jupiter, Aldebaran and the red star Betelgeuse in Orion form a long triangle in the sky. With the Pleiades cluster and the constellation of Orion close by, this is a beautiful sight.

Jupiter is setting progressively earlier, by 8:00 pm local time, so the giant world is harder to see in a telescope. Jupiters' Moons are easily seen in binoculars, and can be followed from night to night changing position, but with a narrow window between twilight and Jupiter setting, you won't have time to see much action..

There are lots of interesting things in the sky to view with a telescope. Especially with Saturn so prominent in the sky.  If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums. Especially during the school holidays.

Printable PDF maps of the Eastern sky at 10 pm AEST, Western sky at 10 pmAEST. For further details and more information on what's up in the sky, see Southern Skywatch.

Cloud cover predictions can be found at SkippySky.

Labels: weekly sky

Seen on my walk into work

Labels: science communicators, telescope

Expedition 26/27 flight engineer Paolo Nespoli poses with Robonaut 2. Image credit Wikipedia commons.

ESA astronaut Paolo Nespoli will be in Australia as part of the National Space Camp.

He will be presenting a FREE public lecture on Wednesday 17 April, 6:00 – 7:30 pm, in “The Braggs” lecture theatre, at the University of Adelaide (off Kintore Avenue). All are welcome.

Paolo's talk will be “6 Months Out of this World” focusing mainly on his experience on the International Space Station.


http://www.sa.aip.org.au

Labels: ISS, Public Lecture, science communicators