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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 45 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. After this Venus and Jupiter draw apart once more making a 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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Thursday, August 18, 2016

 

The ISS crosses the Moon in Adelaide (Sunday Morning 21 August and Monday Morning 22 August 2016)

The ISS crosses the face of the Moon at 7:34:12 am ACST as seen from Adelaide. Click to embiggen.Close up of the ISS crossing the face of the Moon as seen from Adelaide. Click to embiggen.
More detailed timing chart showing the position of the ISS at one second intervals on the 21st.Centreline of the pass on the 21st (where people will see the ISS go through the exact centre of the Moon.

UPDATE:  Of course it was clouded out, wasn't it. The sky waited until I had set the telescope up at the end of the street to cover the Moon thoroughly. Maybe Monday


What is better than seeing the International Space Station glide cross the sky? Seeing it pass in front of the Moon!

This Sunday and Monday mornings (21st and 22nd August), some Adelaidiens have the chance to see the  ISS cross the face of the Moon. Unfortunately, A) the pass is in daylight and B) the ISS crosses the Moon in about 1.5 seconds C) the Moon is pretty close to the horizon.

This all makes for challenging viewing. At the least you will need a telescope with a clear western horizon. On the 21st the Moon is 10 degrees above the horizon when the Moon passes over it,  on the 22nd the Moon is a more friendly 27 degrees above the horizon, but the ISS is further from the centre line, meaning it spend less time in front of the Moon.

You will also need an unwavering gaze, as the ISS will be a tiny black dot flashing cross in one and a bit seconds. If you can do it try and capture video through your scope, running from about 1 minute before to one minute after the predicted time of the pass.

For Sunday, the various predicted pass start times are 7:34:12, 7:34:14 and 7:34:19 (see what I mean about recording a minute before hand)
For Monday, currently I only have 6:42:35  and 6:42:32

For you location, times may vary, it is best to check with Heavens Above (click on all passes so the daylight passes can be seen and choose the pass at 7:34 on the 21st and 6:40 on the 2nd) or CalSky (follow the link to Sun Moon crossings of the ISS) to get timings for your site.

Of course, this assumes that it is not bucketing down rain. Good luck and good viewing


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Wednesday, August 17, 2016

 

Iridium Flare Near Mars (18 August 6:07 pm)

South-Western sky at twilight-

For Adelaideans there will be a bit of a treat tomorrow (18 August) in the twilight. There will be an extremely bright Iridium Flare near Mars and Saturn. While the flare occurs at around civil twilight, it is brighter than Venus, so should be easily seen. However, unlike International Space Station passes, the flares last only a few seconds so you have to be alert to catch them. The flare is predicted at 18:07:31, but you should start watching a minute or so beforehand just in case the timing changes (and to make sure you are looking at the right bit of sky).

While the timing should be similar for most of Adelaide, you can get exact predictions for your site at Heavens Above. My guide to imaging Iridium Flares is here (but in the twilight 15 second exposures are far to long, one second or less are needed)

Flare Details (from Heavens Above)
Date: 18 August 2016
Time: 18:07:31
Brightness: -8
Altitude: 66°
Azimuth: 158°
Satellite: Iridium 60
Distance to satellite: 860 km
Angle off flare centre-line: 0.2°
Distance to flare centre: 3 km
Flare producing antenna: right
Sun altitude: -4.8°

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Carnival of Space #471 is Here!

Carnival of Space #471 is now up at Links Through Space. There is 3D Pizza Printers, asteroid mining missions, exoearths, Taby's Star and much, much more. Head on over and have a read.

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Astrophiz Podcast 7 is Out

Astrophiz Podcast 7 is out now.

Dr Lisa Harvey-Smith talks about building the world's biggest radio telescope, sciencing with indigenous communities and national science Week. I wrap up the Perseids, explain magnitudes and 'What's up in the sky this week'. Dr Nadeshzda Cherbakov introduces Pulsars, and their discoverer, Dame Jocelyn Bell. In the news this week: Science week, Primordial Black Holes, a trip to Proxima Centauri and building a home radio telescope to study the sun.

https://soundcloud.com/astrophiz/astrophiz-podcast-7-dr-lisa-harvey-smith-quiet-zones-dr-musgrave-whats-up-this-week

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