From: TerryMoselat

Subject: Smile for Saturn Event, AP events, Pics wanted, IAA at Cultra, Alien Probes? Web

Date: 18 July 2013 14:44:48 BST

Hi all,


1. SMILE FOR SATURN - 19 July, UPDATE: On Friday evening, NASA’s Cassini spacecraft will photograph Saturn and its entire ring system during a total eclipse of the sun.  Cassini has done this twice before during its previous 9 years in orbit, but this time will be different.

   "This time, the images to be collected will also capture, in natural colour, a glimpse of our own planet next to Saturn and its rings on a day that will be the first time Earthlings know in advance their picture will be taken from a billion miles away," says Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colorado.


   "While Earth will be only about a pixel in size from Cassini's vantage point 1.44 billion kilometres away, the team is looking forward to giving the world a chance to see what their home looks like from Saturn. We hope you'll join us in waving at Saturn from Earth, so we can commemorate this special opportunity."

    Unlike two previous Cassini eclipse mosaics of the Saturn system the July 19 image will be the first to capture the Saturn system with Earth in natural colour, as human eyes would see it. It also will be the first to capture Earth and its moon with Cassini's highest-resolution camera.

   This latest image will continue a NASA legacy of space-based images of our fragile home, including the 1968 "Earthrise" image taken by the Apollo 8 moon mission from about 240,000 miles (380,000 kilometres) away and the 1990 "Pale Blue Dot" image taken by Voyager 1 from about 4 billion miles (6 billion kilometres) away. July 19th, concludes Porco, "will be a day for people all over the globe to celebrate together the extraordinary achievements that have made such interplanetary photo sessions possible. And it will be a day to celebrate life on the Pale Blue Dot."


   To learn more about the public outreach activities associated with the taking of the image, visit: .



2: IAA SATURN EVENT, 19 JULY, at Delamont - UPDATE: To mark this significant event, the IAA will be holding a special Saturn Observing Event, at Delamont Country Park. The imaging event will take place between 22:27 and 22:42 BST, and Saturn will be visible in the twilight sky low in the SW, so we'll be in the picture. Bring your lasers and torches to shine at Cassini for the photo! Check the IAA website for a weather update, but at the moment it looks OK:

   We will start off about 9.0 with a 'Bring Your Own' BBQ (or earlier, if you need plenty of time to get fired up), followed by observing the Moon and Saturn, and then 'posing for the picture'. Yeah, I know that we won't show up, but it will be nice to think that at least some of the photons from Earth which will make up the image in the pixel will have come from us. Bring your 'scopes, torches, lasers etc!

   NB: Saturn will be 1445 million km away, so the light from Earth will take 1h 20m 19s to reach Saturn, and a little bit longer to reach Cassini. Saturn's moons Mimas and Tethys might just appear in the picture, depending on the field of view of the shot.


3. SUMMER EVENTS AT ARMAGH PLANETARIUM. Launch rockets, become a Jedi Master, meet Star Wars Stormtroopers, make your own pinhole camera or take part in our Laser Quest!  These are just some of the wonderful activities on offer this summer at Armagh Planetarium.  We also have three brand new Digital Theatre shows for you to enjoy as well!

For details see:


4: PICS FOR NEW IAA WEBSITE PHOTO GALLERY. President and webmaster Paul Evans has produced an excellent new photo gallery on the updated IAA website. See  We would love to have any photos from members showing past IAA events and activities for a "Pics from the Archive" section. Credits will be given to respective owners of course. 


5. IAA at the 'RSPB BWSO', 10 August.  The IAA has been asked to participate in an event organised by the RSPB at the Ulster Folk and Transport Museum at Cultra, near Holywood, Co Down. Entitled the 'Big Wild Sleep Out', it will feature overnight camping, with all sorts of night-time activities, including skywatching (if clear), and starshows with the mobile planetarium. It will be just coming up to the maximum of the Perseids meteor shower, so we should see some good activity from a fairly dark site, if it's clear.

  The event is now on the RSPB, NMNI, Cotswold Outdoor and IAA websites. Angus and Davey at Cotswold Outdoor will be offering prizes of a tent worth £250, 5 family spots and we also have 5 RSPB goody bags with mugs, biscuits, chocolate and RSPB wildlife books all to be won!


6. Are Alien Probes Here Already? See and^headlines

   I think there's a slight flaw in the reasoning here. Quote "In order to search the entire Milky Way in 10 million years (not long in space terms) our aliens would have to travel at 1/10 the speed of light."

    But that would just be a simple crossing of the galaxy from one side to the other, equivalent to driving through Belfast from one side to the other along the Westlink. That's not 'searching all of Belfast'.

    To explore every star in the MW would take a lot longer!  There are about 100,000 million stars, with an average separation of 4 LY, a total journey of 400,000 million LY (in simplified terms). So to travel to every single star at 1/10 light speed would take 40,000 million years, almost 3 times the age of the universe!

    One might not want to visit every star, but to visit even 10% of them would still take 4,000 million years. So they propose that the probes that are sent out are 'self-replicating', using interstellar material that they would 'sweep up' along their journey. Since one needs fairly exotic materials, including very rare metals, to make a probe with an advanced onboard computer, and capable of precise course corrections and of detecting any advanced life on an alien planetary system, and communicating with that life, that's a tall order! To give a simple easy to understand example: How many times would an advanced very high tech probe have to travel between the Sun and Alpha Centauri to sweep up enough material to replicate itself (including the ability to produce further replicas)? At least 1,000 times?

   And assuming it would use solar energy for the processing of the raw materials, it could only do that efficiently during the short period it spends close to each star. And if it's travelling at an AVERAGE of 1/10 light speed, then the speed near the star during each slingshot manoeuvre will have to be much higher - say 1/5 light speed. And at that speed the probe would spend only about 100 minutes inside the orbit of Mars at each star!

   Also, at that speed, it won't have much time to search for signs of life in any planetary system. And what happens if it detects life? According to their scenario, it then stays in that solar system. Which means slowing down from 1/5 light speed to the speed of an orbiting planet. That would require a HUGE amount of energy!

   And then what? When the new civilisation become advanced enough to detect the probe, the probe says 'Hello. Nice to meet you. I've come from planet W, orbiting star X, which lies Y light-time units away in the direction of Z'. Fine, that's nice to know. But what does the originating civilisation get out of that? In other words, what would be the point? TM.

7. INTERESTING WEBLINKS:^headlines^headlines^headlines (I'm not entirely convinced! TM) (not quite accurate)




9. TWITTER: Follow the IAA on Twitter:  at signIaaAstro

10. BBC THINGS TO DO WEBSITE: See the forthcoming IAA events on Look under 'Countryfile'.


11. JOINING the IRISH ASTRONOMICAL ASSOCIATION is easy: This link downloads a Word document to join the IAA. If you are a UK taxpayer, please tick the 'gift-aid' box, as that enables us to reclaim the standard rate of tax on your subscription, at no cost to youYou can also make a donation via Paypal if you wish: just click on the 'Donate' button.  See also


Clear skies,

Terry Moseley

mob: (0044) (0) 7979 300842

I'm now back on Twitter, after some temporary hiccups: at signterrymoseley2