From: TerryMoselat signaol.com

Date: 1 August 2009 22:28:10 BST

Subject: Eclipse report, Lecture, Star Wars, Jupiter Impact & Occultation, Perseids


Hi all,

 

1. TSE REPORT: The total solar eclipse (TSE) on 22 July was predicted to be the one which would be seen by the greatest number of people ever, because the track crossed such a highly populated area of the globe (there are 19 million people in Shanghai alone!). In fact, it was probably the TSE which was missed by the greatest number of people ever! A major weather system spoiled the view for almost everyone in Eastern China, which is where most people were hoping to see it. A few were very lucky with local holes in the lower clouds, and got views of totality through higher cloud and haze, but only those in remoter Western China got decent views. Some also saw a shorter totality from a few parts of India, but as expected the major part of that subcontinent was clouded out. And most suprisingly of all, even the cruise ships which were hoping to find the best weather along the track of totality in the Pacific had almost uniformly bad luck!

  Our group travelled to Yanguan, South of Shanghai on the Qiantang River estuary, along with many thousands of others. The weather forecast that morning was appalling, but one can only hope..... It was totally cloudy, but hot & humid, when we arrived, and when the rain started it at least cooled down those of us who stayed out in it!

  But after a while some brighter patches in the cloud appeared and soon we could see the opening partial phases. We never got a totally clear view, but hopes began to rise slightly that we might glimpse totality. However it was not to be: thick cloud persisted from about 10 minutes before 3rd contact to about the same time after totality ended! We did see the effect of the onrushing shadow over the clouds, and it got very dark in mid-eclipse. Even more impressive was the trailing edge of the shadow: we could see the lightening effect on the clouds to the East, and suddenly it was rushing over us & the sky was brightening again.

   We stayed on to see the world-famous tidal bore on the river. It's the world's biggest, and can reach a height of 9 metres, but this time it was only about 2-3 metres: still very impressive as it extended across the full width of the river estuary - about a mile across at that point.

   However, the rest of the trip made up for the disappointment of missing totality: Shanghai is an amazing city, having overtaken New York in terms of skyscrapers, and the Jade Buddha, Xi-an City Walls, Terracotta Warriors, Forbidden City, and Great Wall would have been worth the trip on their own. Some even took a ride on the 'Maglev', the world's fastest train, which runs from Shanghai to the airport, and reaches a speed of over 430 kph!

   And among the 19 million people in Shanghai, we bumped into Terence Murtagh, former Director of Armagh Planetarium, and Dr Don Pollacco, Research Astronomer at QUB! Not to mention Uel and Ruth Webb from Belfast, IAA members who chose to go with a different tour  :-(  who were observing near the same position as us. Small world, eh?

 

2. IYA 2009  PUBLIC LECTURE at ARMAGH PLANETARIUM: Tuesday 4 August, 7.30pm

    "Cosmos versus Canvas: Tensions between Art and Science in Astronomy 

Images", by Dr Jayanne English (University of Manitoba, Winnipeg, Canada)

    Summary: Dr Jayanne English of the University of Manitoba, Winnipeg, Canada will deliver a free public lecture in the Armagh Planetarium on Tuesday 4 August at 7.30 pm. The title and brief summary of the lecture are: 

"Cosmos versus Canvas: Tensions between Art and Science in Astronomy Images"

     Dr English is an outstanding speaker who uses bold colour images from telescopes to act as extraordinary ambassadors for astronomers because they provoke huge curiosity in people's minds.  The images are especially popular during the International Year of Astronomy, but raise the question whether the snapshots are documenting physical reality or are merely artistic "space-scapes" created by digitally manipulating astronomical images.

  The lecture will provide a tour of how original black and white data, for example from the Hubble Space Telescope, are converted into the familiar colour images gracing newspapers and magazines.  Each image can be regarded as a battlefield where the attempt by scientists to represent their discoveries accurately all but drowns out the artistic voice of

visual literacy.  Yet sometimes in this battle between cultures of science and visual art, both sides win.  This struggle will be presented from the perspective of a professional astronomer who has also trained as an artist.

    This public lecture is part of the Armagh Observatory's programme of events to support the United Nations International Year of Astronomy 2009.

   For tickets to the public lecture, please contact Neil Cullen at the Armagh Planetarium; Tel: 028-3752-4725; Fax: 028-3752-6187; email: neilat signarmaghplanet.com or Aileen McKee at the Armagh Observatory; Tel: 028-3752-2928; Fax: 028-3752-7174; e-mail: ambnarm.ac.uk.

For full details, see: http://star.arm.ac.uk/press/2009/jenglish_090804.html 

 

3. STAR WARS EXHIBITION: "GALACTIC TREASURES". his exhibition, run in conjunction with "Emerald Garrison - Knights of the Empire", runs at Armagh Planetarium from 1 to 28 August. Normal admission charges apply. See www.armaghplanet.com and www.irelandgarrison.com for more details.

 

4. JUPITER IMPACT & OCCULTATION:

IMPACT: While I was away in China, Jupiter was struck by an asteroid or comet, which left a prominent dark 'scar' in the clouds in Jupiter's South Polar region, which was first spotted by Australian astronomer, Anthony Wesley. The large black spot was similar to those left when comet Shoemaker-Levy broke up and impacted the planet, and happened exactly 15 years later. The black mark is fading now, but may still be visible in good conditions.

OCCULTATION: As already notified, a rare event occurs on 3 August, when Jupiter will occult the 6th magnitude star 45 Capricornii, at about 23.50 BST (the exact time depends on your location). Jupiter will be climbing in the SE sky as the occultation starts, so anyone with a reasonably clear horizon in that area should be able to observe it.

   The star is one of the brightest that Jupiter will ever occult during our lifetimes, so this will be interesting to watch, and video. The star will be a bit fainter than Callisto, the faintest of the 4 Galilean moons. It will disappear behind the Southern limb of the planet, at about the position of the SSTB (South South Temperate Belt). Jupiter will be only 11 days before opposition, so the phase effect will be negligible: in other words the star will disappear behind the illuminated edge of the disc, but of course there will be considerable limb darkening, as the Sun will be setting on Jupiter's horizon at this point.

   And of course Jupiter will be retrograding as it approaches Opposition, so the star will be occulted on the planet's WEST limb, and will reappear at the EAST limb.

   The 4 Galilean moons will also be visible, lying in the plane of Jupiter's equator, so there's no chance of mistaking them for the star. Closest in to the planet on the same side as the star will be Europa, which will actually go into eclipse in Jupiter's shadow at 00.47 (on the 4th), and then Io. Ganymede and Callisto will be much further out, on the opposite side of Jupiter. The event will last until about 01.50, again depending on your location.

   If you can do well-timed video imaging of this event, it will be very useful for analysing the composition and density of Jupiter's atmosphere.

   Although the star is a point source (unlike the Galilean moons), the occultation will not be instantaneous, as it will fade, probably over a period of several seconds at least, maybe up to 30 seconds, as its light passes through ever denser layers of the Jovian atmosphere. In fact it's possible that it may disappear and reappear again briefly due to refraction effects. Accurate timings of these events will also be useful, at both disappearance and reappearance.

   The reappearance will occur with Jupiter higher in the sky, but this will be much more difficult to observe, as there will be no sign of the star until it suddenly starts to reappear. See the websites below for more information.

   For visual observing, probably at least 100mm aperture will be required, with a magnification of about 150 or more - whatever the seeing will bear. Send any reports or images to the IAA website www.irishastro.org or to Andy McCrea for STARDUST: s.mccrea980at signbtinternet.com. Good luck.

   More details on: http://www.iota-es.de/jupiter2009/jupiter_timeline.html and

http://www.iota-es.de/jupiter2009/jupiter_disretime.html 

5. PERSEID METEOR SHOWER: The best known of the annual showers will reach maximum on the afternoon of August 12, but as the peak is fairly broad we should see good meteor rates on the nights of both 11/12 and 12/13 August. In fact, some early members of the shower are already appearing, and rates will gradually increase until the maximum, and then decline rather more quickly, with the last ones being see around 18 August. The radiant lies close to Alpha Persei at maximum, and any meteor appearing in the general region of the famous 'Double Cluster' in Perseus to slightly North of Alpha Persei from now until about 18 August will almost certainly be a Perseid. The meteors are fast, and often bright. However, moonlight will interfere with the early part of the shower, with Full Moon on 6 August, and the Last Quarter Moon rising at the end of twilight on the date of maximum. Towards the end of the shower there will be a short opportunity to observe between the end of twilight and moonrise.

   However a Last Quarter Moon is not so bright as to prevent observation, so do have a look if skies are clear around 11-15 August. Maximum rates would be about 80 per hour under ideal conditions: This year we might see around 40-50 on the night of 12-13 August if the sky is totally clear.

 

Clear Skies,

 

Terry Moseley