Derby and District Astronomical Society

The Journal of the Derby and District Astronomical Society
May - August 2006


Aries May-Aug 2006 Welcome to this edition of Aries!

Well, at long last, here it is! Sorry for the long wait for this issue, but things ran away with me and before I knew where I was, were heading for September! So apologies once again for the late appearance of this edition of Aries, in fact as I am completing this edition, I have started work on the September Ė December edition! Phew! I hope to have that edition published by the November meeting, but knowing my luck of late, it may even be the December meeting! So watch this space!

So what has been going on since the last edition of Aries, well, quite a bit really! First up we have had a number of highly successful public events during the last few months, culminating in our presence at the Relay for Life event at Moorways Stadium during Saturday 17th and Sunday 18th June (see the Society News pages for more details).

Also during this period, we have had, not one, but two Shuttle missions! The second Return to Flight mission, STS-121/Discovery took off on the 4th July (of course!) and had the good grace to land on 17th July, a day away from me leaving for Heathrow to go to Greece! There was no way that I was going to worry about that mission while I was on my hols! But if they had stayed up any longer I would have gone spare without access to NASA TV to see if everything was all right!

The second mission is not a Return to Flight mission, this is the first construction mission to the International Space Station since October 2002, when Space Shuttle Atlantis visited the station, and quite appropriately, it was Atlantis that launched on 9th September on Shuttle mission STS-115. The mission is in progress as I write this editorial - this is Atlantisí first flight in over three years! The main goal of this mission is to deliver the P3/P4 solar arrays and the truss structure for the ISS. These items are the heaviest items that the Space Shuttle has ever taken into orbit. The mission is scheduled to last 11 days, and yes, there has been foam loss of the External Tank on both missions, but from the images Iíve seen of the STS-115/Atlantis ET, there seems very little cause for concern, at least to my mind. The mission is progressing well and Atlantis is undamaged.

Staying with the space flight motif a little longer (alright! who booed!), NASA announced the names of the spacecraft and vehicles that will replace the Shuttle in 2010. The Crew Exploration Vehicle (CEV), which is basically a 'muscle-bound' Apollo Command and Service Module (CSM), is to be called Orion, and will be built by Lockheed Martin Corporation. The lunar lander module has yet to be named (Iíve yet to hear any announcements). The vehicles that will be designed for these spacecraft are expendable launch vehicles based on Space Shuttle-derived technology. The vehicle that will launch the CEV uses SRB/ET technology and will be called Ares 1 (does that sound familiar to you? echoes of Apollo? Saturn 1B maybe?) and the larger vehicle that will launch the lunar landing module, will be 300-feet plus in height and will be called? Guessed it yet? No! I am surprised the clues were there! This monster vehicle will be known as the Ares V (Saturn V anybody?). The whole programme will be known as the Constellation Programme. I really do think that NASA is starting to live in the past! Hmmmm? I feel an article coming on! Be warned!

But thatís not all, leaving spaceflight behind, we come to the rather studious pursuit of planetary nomenclature. At the end of August (August 24th to be exact) at a meeting of the IAU in Prague a decision was made that will completely revise all the astronomy textbooks, yes folks! your astronomical libraries are not as up to date as you once thought! For on that date, after much wrangling and debate, Clyde Tombaughís little world Pluto, lost its planetary status. The debate as to whether Pluto should keep its privileged position as a planet, has been raging for years, but it reached a new intensity with the discovery of large Kuiper Belt Objects, like Sedna and the recently confirmed 2003 UB313 unofficially know as Xena. In the light of these discoveries, it was suggested that Pluto and its recently discovered friends be known as 'Plutons' and new class of planetary body based upon Pluto as the index body. But this opened up a potential can of worms, and that was, if more worlds like Sedna and 2003 UB313 were discovered, they would have to be classified as Plutons and we could, in a few decades be living in a Solar System with dozens, if not hundreds of recognised planets! Where do you draw the line?

So an alternative plan was put forward, and this involved setting up a definitive definition of what constitutes planet. For a body to be classed as a planet it must:

Now that definition is a little bit ropy I grant you, but it is the best that the IAU could do at the time, and based on this definition, Pluto was demoted to the status of a dwarf planet. Pluto was automatically disqualified as a planet because it is part of the Kuiper Belt and it has not cleared out all objects in its vicinity and neither does it dominate the Kuiper Belt. Plutoís fate was really sealed when 2003 UB313 was discovered, as it is slightly larger than Pluto. Also, the barycentre of Pluto and its moon, Charon, lies in the space between. In the case of the Earth, the Earth-Moon barycentre lies within the mantle of the Earth, so by that definition, Earth is a planet, Pluto is not. So, Sedna, 2003 UB313 (Xena), and yes, even Ceres, the largest of the asteroids and is spherical in shape, join Pluto in the dwarf planet classification. So we now have to get used to living in Solar System of eight 'classical planets', Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune and a number of dwarf planets, and their numbers are sure to grow over the coming years. Even though I think that this was the right thing to do, I still have a twinge of sadness for poor old Clyde Tombaugh, heís lost a planet and gained a dwarf planet.

So, what's in this edition of Aries then?

We have the usual Society News pieces and Astro News Desk pieces. We also have another Letter to the Editor thanks to Claire Spencer. All this talk about Pluto and the Kuiper Belt has set you all talking, please keep your comments coming in, Iím sure the readers would like to hear them.

We have an article from Tony Razzell for this edition of Aries - it is a very interesting, if not highly technical piece concerning Tony's radio astronomy experiments at 12 Ghz. Tony submitted this article to the BAA Radio Astronomy Journal Baseline. Many thanks to Tony for letting me reproduce it for Aries.

Graham Ensor has written a report about the Dennis Sciama Memorial Lecture at the Martin Wood Lecture Theatre in Oxford, which took place on Friday 24th February 2006. The speaker for that lecture was none other than Professor Stephen Hawking.

The second part of my New Horizons article appears in this issue, and rounds off what we already know about Pluto and highlights the mission of the New Horizons spacecraft.

I know I said in the last editorial that I was going to publish the first part of my 'Mining the Sky' article series in this issue, but, again, things have not worked out how I would have wished, so I will include that article in the September Ė December 2006 edition of Aries.

Anthony Southwell So enjoy this edition of Aries and get used to living in a solar system with eight planets!


September 2006