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Sunday, August 28, 2016

 

GeomagneticWarning (29-30 August, 2016)

The Australian Space Weather Service (SWS ) has now  issued a  Geomagnetic Warning and on 29-30 August UT from  high speed solar wind stream a coronal hole. This translates out to being around the 30th to possibly the 31st for Australians. Evening and morning skies are Moon free, but cloud is problematic. It is possible aurora may be seen in Tasmania and Southern Victoria if the minor storms eventuate.

Dark sky sites have the best chance of seeing anything, and always allow around 5 minutes for your eyes to become dark adapted.

As always look to the south for shifting red/green glows, beams have been reported consistently over the last few aurora and a large green "blob" has been seen, as well as bright proton arcs and "picket fences".

As don't forget the continuing "Planet dance". All five bright planets are visible in the early evening sky to the west. While Venus and Jupiter were at their best on Sunday the 28th, they will look great for weeks to come, with the Moon jining Venus, Mercury and Jupiter on September 3.
http://astroblogger.blogspot.com.au/2016/07/a-rare-planet-dance-in-august-2016.html
Here is the near-real time satellite view of the clouds http://satview.bom.gov.au/
Cloud cover predictions can be found at SkippySky.  

The all sky aurora camera in Northern Tasmania at Cressy may be helpful.
<http://www.ips.gov.au/Geophysical/4/2>

SUBJ: SWS GEOMAGNETIC DISTURBANCE WARNING 16/35
ISSUED AT 2342UT/27 AUGUST 2016
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

The effect of a high speed solar wind stream from a recurrent
coronal hole may raise the geomagnetic activity to unsettled
to minor storm levels on 29 and 30 August.

INCREASED GEOMAGNETIC ACTIVITY EXPECTED
DUE TO CORONAL HOLE HIGH SPEED WIND STREAM
FROM 29-30 AUGUST 2016
_____________________________________________________________

GEOMAGNETIC ACTIVITY FORECAST
29 Aug:  Unsettled to minor storm
30 Aug:  Unsettled to minor storm


Further monitoring at
http://www.ips.gov.au

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Venus and Jupiter at Closest Approach (Sunday August 28, 2016)

Venus and Jupiter in  conjunction with Mercury nearby, Sunday August 28, 2016. Inset shows 3 x Zoomed Venus and Jupiter, with Mercury visible at top left and beta Virginis just visible near Jupiter. Image taken with a Canon IXUS, 6 second exposure, 400 ASA at 6:50 pm ACST. Click to embiggen.Venus (bottom) and Jupiter and its Moonsin   a 25mm eyepiece with my 114 mm Newtonian reflector. You can see Callisto (furthest) Europa near Jupiter) and Ganymede and Io merged almost on top of Jupiter. Significant tree interference. Click to embiggen.

After a clear day and beautiful warm weather, the clouds invaded the evening sky again. This tie there were enough breaks in the cloud to get my telescope out and do some imaging just before the trees got in the way. Sadly I couldn't adjust the exposure down, and the refraction spikes you see are from the tree branches, but the Galillean satellites came out nicely.

Igot some good non telescope exposures, despite thin cloud hanging around. The twilight colours were muted by the cloud, but the pair of Venus and Jupiter, with Mercury nearby, was absolutely brilliant. I pointed them out to some joggers who had to vere around my kit, they were suitably impressed as well.

We won't see Jupiter and Venus this close and accessible for decades. So I am somewhat pleased to have seen them (and helped others see them). The planet dance isn't over, and on September 3 Venus, Jupiter and Mercury are joined by the thin crescent Moon.

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Proxima Centauri b, The Exoplanet Next Door

Proxima Centauri b as visualised in Celestia. I have used a Venus surface for the visualisation as it is close to the inner edge of the habitable zone, but if it has no or a thin atmosphere it may very well be an ice world. Click to embiggen.

When I was in high school (mumble) years ago, our zoology teacher was a bit of a science fiction buff,  which gave her extra credit points in the eyes of a science fiction loving teenager. She set us one assignment to write about organisms on a tidally locked world. A key intersection of my twin loves of biology and astronomy, I turned in a fairly ummm...average assignment none the less, about burrowing animals on the dessert like sunny side of the world (I didn't think much about the atmospherics and hot pole/cold pole heat transfer).

This was all brought back by the announcement of a planet orbiting Proxima Centauri. Proxima Centauri is part of the triple star system Alpha Centauri. Alpha A and B are orange sun-like stars, but Proxima is a red dwarf orbiting somewhat distant from the other two.

The sky as seen from the southern hemisphere and hour and a half after sunset. Proxima Centauri is almost mid way between Riget Kent (alpha Centauri) and the dim star alpha Circinus off to the left. Click to embiggenA binocular field view of the location of Proxima Centauri. Proxima is too dim (magnitude 11) to be seen in binoculars, but is visible intelescopes and long duration exposures. But is hard to tell from the other stars. Click to embiggen.

The planet around Proxima is both "earth-like" and in the habitable zone. This is particularly exciting. Proxima is only 4.26 light years away, so in principle future instruments might be able to resolve it. If we are really lucky, the planet will transit its sun, so we can get some ideas about its diameter and atmosphere without new instruments.

As well, Proxima Centauri is the closest star to us, only a hop skip and a jump galactically speaking. To be sure, the technical challenge is enormous. Our current speediest spacecraft, Voyager 1 and New Horizons, woul take on the order of 8,000 years to get there. These craft travel at only around 0.005% of the speed of light, a recent proposal for a fleet of "starchips"; postage sized spacecraft carried on light salis, could reach 20% of light speed and get to Proxima b in a lifetime (including development).

The challenges of such a spacecraft are enormous, but not insurmountable. It will be very interesting to see what the next decade brings.

"Earth like" merely means it is small and rocky, "habitable zone measn nothing more than it is in the region around the star that liquid water can possibly exist on. But as a reminder, both Venus (searing hell) and Mars (frozen wasteland) are also (just) in the Sun's habitable zone. Whether liquid water exists on the world depends on if it has an atmosphere, and how dense it is. The occasional flares from the star, more powerful than our solar flares, will be a challenge to atmospheric stability, let alone life.

I have as usual made a Celestia file for the system. Original paper here. Copy the data here to a plain text file (Proximab.ssc) and copy the file to the Celestia extras folder.
=======================================8<==cut===8<===Proximab.ssc=======================================================
"b" "Proxima"

# Earth-like world that orbits the red dwarf star Proxima Centauri, the closest star to the Solar system
# Nature 536, 437–440 (25 August 2016) doi:10.1038/nature19106
# http://www.nature.com/nature/journal/v536/n7617/full/nature19106.html

{
Texture "venussurface.*"
# Using Venus as it is close to the leading edge of the habitable zone.

Mass 1.27     # M.sin(i) = 1.27 (1.10-1.46)
Radius 6300     # 1.27 Earth Mass radius a guess

#InfoURL "http://en.wikipedia.org/wiki/Alpha_Centauri_Bb"

EllipticalOrbit {
Period 0.0306251
SemiMajorAxis 0.0485
Eccentricity 0.0 #fixed
ArgOfPericenter 310 #from paper
Inclination 90.0322 #guess
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Proxima/b"
{
Texture "venussurface.*"
OverlayTexture "ganymede-lok-mask.png"
}

}

===================================8<==cut===8<===================================================================

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Saturday, August 27, 2016

 

Venus and Jupiter Conjunction, Saturday 27 August 2016

Venus and Jupiter in (almost) conjunction, Saturday August 27, 2016. Inset shows 3xZoomed Venus and Jupiter, with Mercury just visible at top left. Image taken with a Canon IXUS, 1 second exposure, 400 ASA at 6:27 pm ACST. Click to embiggen.

Last night clouded out the narrowing gap between Venus and Jupiter (which was lucky, as my kid taxi duties stopped me seeing it anyway) but today dawned sunny and clear but for a few wisps of cloud. It stayed that way for most of the day, so I organised with some friends we would meet on the esplanade above the beach and I would bring the telescope.

So of course it clouded over just after we made the arrangements. I took the scope up anyway, on the off chance there was a break in the cloud, and we stood around waiting while the kids circled us on their scooters.

And there was a break, or rather a thinning and for about 10 minutes of so we could see the pair together above an ominous cloud bank. I had the scope set up and was able to show the kids Venus and Jupiter together in the 114 mm Newtonian with 20 mm eyepiece, sky was too bright and cloudy to see Jupiter's Moons though. I got a few shots off and was even able to see Mercury in the zoomed images (not visible to the unaided eye).

Then the ominous cloud bank completely swallowed the planets, much to everyone's dismay. By the time I had slewed the scope to Saturn to assuage the sadness, the cloud bank covered it (and Mars) too.

So we retreated to the fire my mate had built and chatted in its warmth while waiting for the clouds to break again. They didn't but we ate hot-dogs and toasted marshmallows and then went inside our friends house to watch Minions and chat. Pretty good way to end an expedition Ithink.

With any luck tomorrow, When Jupiter and Venus are closest, will be clear.


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Thursday, August 25, 2016

 

Venus and Jupiter Meet in the Twilight (27, 28 August 2016)

Western evening sky on Saturday August 27 looking west at 40 minutes after sunset. Jupiter and Venus are around a lunar diameter apart with Mercury nearby.  Similar views will be seen throughout Australia at the equivalent local time. (click to embiggen).Western evening sky on Sunday August 28 looking west at 40 minutes after sunset. Jupiter is spectacularly close to Venus with Mercury nearby.  Similar views will be seen throughout Australia at the equivalent local time. (click to embiggen).Simulated telescopic view of Jupiter and its Moons, Venus and the star Zavijava. The field of view of  a 24mm eyepiece in a 114 mm Newtonian refractor is simulated. Click to embiggen.

If you have been watching the western twilight over the past week or so you will have seen two bright dots coming closer together. These are Venus and Jupiter, and on Saturday and Sunday they meet in the most awesome event of the current Planet Dance.

With speedy Mercury nearby, the planetary pair form a long pointy triangle. On Saturday and Sunday Venus and Jupiter will be around a lunar diameter apart (33 arc minute and 28 arc minutes respectively, if you want to get technical). That's about half a finger-width (when you hold your finger out at arms length).

That means not only will they be together in binocular fields (and Mercury, just), but they will be together in wide field telescope eyepieces. You should be able to see the bands on Jupiter (just) and the Galilean Moons together with Venus. Venus will be painfully bright in a telescope eyepiece, and is featureless gibbous shape, but seeing the two planets together will be great. The second brightest star in Virgo, Zavijava, should also be visible in telescope eyepieces.

While the three planets are visible in the western sky from half an hour after local sunset to at least and hour and a half after sunset, the best time to look is between 40 minutes to an hour after local sunset. This is when the sky is dark enough to see all three easily, but there is still plenty of twilight colour to make the sky dramatic and the planets are hight enough above the horizon that most normal horizon clutter doesn't get in the way.

Venus and Jupiter are the brightest objects in the sky once the sun has set, and Mercury is the third brightest object above the western horizon just near Venus and Jupiter, so spotting the trio should be easy.

40 minutes after sunset Venus, Jupiter and Mercury gleam above the twilight colours (25 gust). Click to embigenAn hour after sunset sunset Venus, Jupiter and Mercury are brilliant above the horizon (24 August). Venus's light forms a path in the sea. Click to embigen

Even if there is a bit of cloud about, pop out now and again to see if you can get a glimpse of the wonderful line-up.

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Wednesday, August 24, 2016

 

Carnival of Space #472 is Here!

Carnival of Space #472 is now up at Everyday Spacer. There is planets around Proxima Centauri, Keeping Mars warm, a rare nova and much, much more. Head on over and have a read.

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Astrophiz Podcast 8 is Out

Astrophiz Podcast 8 is out now.

Dr Cherbakov tells us about the discoveries and passing of Owen Slee, and explains how neutron stars form, and how some become pulsars. I continue ‘the dance of the planets’, and introduce ‘Ian’s Tangent’ a new segment, and this week it is about observing the moons of Jupiter using binoculars and 'What's up in the sky this week'.

In the news this week: the LOFAR Array, @Astrokatie nails some misconceptions, a 5th force of nature? … and exploding white dwarf stars.

https://soundcloud.com/astrophiz/astrophiz-podcast-8-dr-cherbakov-neutron-stars-dr-musgrave-whats-up-this-week

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Tuesday, August 23, 2016

 

Mars, Antares and Saturn from a Straight Line (Wednesday August 24, 2016)

Mars is almost between the red star Antares and Saturn on the evening of 23 August. Canon IXUS, ASA 400, 15 second exposure, 10x images stacked in Deep Sky Stacker. Click to embiggen.Mars forms a triangle with the red star Antares and Saturn on the evening of 8 August. Canon IXUS, ASA 400, 15 second exposure, 10x images stacked in Deep Sky Stacker. Click to embiggen.

While most of the attention has been on the dance of Venus, Mercury and Jupiter in the twilight, if you have been watching Mars in the evening over the past month, you have seen it enter the head of the Scorpion. forming a triangle with the red star Antares and Saturn, you will have seen the triangle get shorter and shorter. Tomorrow night is the climax of this movement, with Mars being almost directly between Antares (the name means "rival of Mars") and Saturn.

If you have clear skies, pop out any time after 8:00 pm and look to the west. the Scorpion, Antares and the two planets will be very obvious, it should look very lovely.

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The Sky This Week - Thursday August 25 to Thursday September 1

The Last Quarter Moon is Thursday August 25. The New Moon is Thursday September 1. Venus and Jupiter are spectacularly close on the 27th and 28th. Mars and Saturn are visible all evening long. Mars is almost directly between the red star Antares and Saturn on the 25th. In the morning skies on the 26th the waning Moon is close to the bright star Aldebaran.

The Last Quarter Moon is Thursday August 25. The New Moon is Thursday September 1.

Evening sky on Sunday August 28 looking west at 60 minutes after sunset. Jupiter is spectacularly close to Venus with Mercury nearby.  Similar views will be seen throughout Australia at the equivalent local time. (click to embiggen).

Jupiter was at opposition on the March 8th, when it was biggest and brightest as seen from Earth.

Jupiter is in the western evening sky as the sun sets, and is  too close to the horizon for decent telescopic observation. Jupiter's Moons will be an still be excellent sight in binoculars for a short while before it sets.

Venus continues to rise above the twilight glow this week. Venus and fleet Mercury are sufficiently high in the dusk sky to be seen easily. From a little after half an hour to an hour after sunset to a bit over an hour after sunset, Venus, Mercury, Jupiter make a nice triangle the dusk sky. If you extend a line from the apex up it meets  Mars, Anatres and Saturn.

Mercury continues to return to the horizon.

Jupiter, Mercury and Venus form a triangle in the dusk, with Jupiter coming closer and closer to Venus during the week, becoming very close on the 27th and spectacularly close the 28th. A detailed guide to this rare event (the next one will be in 2065) is here.

After this Venus and Jupiter draw apart once more making a broad triangle with Mercury.

Evening sky on Thursday August 25 looking west as seen from Adelaide at 22:00 ACST. Mars, Saturn and Antares form a  straight line. Similar views will be seen elsewhere in Australia at the equivalent local time. (click to embiggen).

Mars is high in the western evening skies in the body of the Scorpion.

Mars moves further down the body of the Scorpion this week. Mars starts the week almost directly between Antares and Saturn. During the week. Mars moves away from Saturn and the red star Antares once more froming a triangle with them.

Mars was at opposition on May 22,  and is still visibly dimming, but is still a modest telescope object. It is visible all evening long. In even small telescopes Mars will be a visible disk, and youmay even be able to  see its markings.

 Saturn was at opposition on the 3rd of June. However, Saturn's change in size and brightness is nowhere near as spectacular as Mars's, and Saturn will be a reasonable telescopic object for many weeks. Saturn is reasonably high in the evening sky and is readily visible below Scorpius. Saturn is still high enough for good telescopic observation in the evening. In even small telescopes its distinctive rings are obvious.

There are lots of interesting things in the sky to view with a 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.


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, August 22, 2016

 

Venus, Mercury and Jupiter 22 August 2016

From bottom to top, Venus, Jupiter  and (dim) Mercury on the evening of 22 August (Canon IXUS ASA 400, 1 second exposure) at 6:33 pm ACST. Click to embigen.From bottom to top, Venus, Mercury and Jupiter  on the evening of 17 August (Canon IXUS ASA 400, 1 second exposure) at 6:33 pm ACST. Click to embigen.

Another entry in our Planet Dance, Venus is rising higher, Mercury and Jupiter are dropping lower, and the triangle formed by our trio becomes more acute (see previous shots here, here and here). Venus and Jupiter will continue to move closer, leading up to their spectacular close approach on the 27-29th.

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Sunday, August 21, 2016

 

Venus, Mercury and Jupiter 17 August 2016

From bottom to top, Venus, Mercury and Jupiter  on the evening of 17 August (Canon IXUS ASA 400, 1 second exposure) at 6:33 pm ACST. Click to embigen.From bottom to top, Venus, Mercury and Jupiter  on the evening of 14 August (Canon IXUS ASA 400, 1 second exposure) at 6:33 pm ACST. Click to embigen.

Continuing our Planet Dance, Venus is rising higher, Mercury and Jupiter are dropping lower, and the trio now form a definite triangle (see previous shots here and here). Venus and Jupiter will continue to move closer, leading up to their spectacular close approach on the 27-29th. Now if only the clouds woudl go away.

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