Astronomy Log

I attended my first Star Party the other week and both the hosts of the party used green laser pointers to point out which celestial objects we were actually looking at through the telescopes and on the large projection screen.

The green laser pointers were amazing and the beam of light went all the way through the sky to the object, which made it look like the beam was actually touching the stars!

So I decided to get myself a green laser pointer, I chose a Revelation Green Laser Pointer from Telescope Planet, it arrived quickly and came in a presentation metal box and it included 2x AAA batteries as well as instructions.

The laser pointer has a 5 mW output and has a beam range of over 12,000 ft. The unit is of very high quality and a great present for any astronomer, especially at the price of around £30.

The laser pointer can also be used in conjunction with a universal bracket which can be fitted to most telescopes which allows the laser pointer to be used as a very capable finderscope.

You can buy the green laser pointer from Telescope Planet here.

Looking for an unusal gift for someone? How about Astronaut Food? You can get Strawberries and Neopolitan Ice Cream.

Now you can eat the same food Nasa Astronauts eat on space missions. The foil sachets contain freeze dried strawberries or ice cream which last almost indefinitely, making them suitable for long space flights.

As they are eaten, saliva in the mouth re-hydrates the ultra-light chunks, returning them to their original state. Just Pop a Strawberry one in your mouth and it swells up magically to a full size fully flavoured succulent fruit. Brilliant for parties, perhaps Star Parties!

Each Astronaut Food packet is £2.99, you can buy the Strawberries Astronaut Food here and buy the Neopolitan Ice Cream Astronaut Food here.

Tonight’s talk at the Cambridge Astronomy Assocation was by Alan Aylward who was telling us everything we needed to know about aurorae.

Aurora can actually be seen from space, and some images demonstrated this, with views from the NASA shuttle. Aurora were actually treated with fear in historical times.

Early research showed that aurorae actually extended around the poles of the Earth in a ring ~(as shown in the accompanying image), and the ring (more commonly called the “aurora oval”) does actually move, so depending on where it is, you may see an aurora.

Aurora’s have actually been visible from the UK, and we were told that in the UK we may have the chance to see aurora up to three times a year, but cloudy nights decrease our chances of viewing one.

The Earth’s aurorae are actually triggered by the Sun, as the solar winds interaction with the magnetosphere is mapped down into our atmosphere. We were also informed that there are different colours to the aurorae. A red aurora means that the aurora is very high in the atmosphere, whilst the middle height colour is green and a low aurora provides a purple colour in the sky.

We were told that Coronal Mass Ejections (CME’s) create the Earth’s aurorae activity, but other planets also have aurorae including Jupiter which creates its own aurorae with a lot of help from the volcanic moon Io. Saturn also have aurorae as well, but they are 100x less active than Jupiter’s.

Overall we learnt, that anything with magnetic fields has aurorae. This was a great talk that told us everything we wanted to know about aurorae, and even more besides.

On Sunday I visited the Cambridge Astronomy Association for the Impact Day 2008, which was a free day of lectures about comets and meteorites.

As well as a full day of lectures there were also a number of stalls selling astronomy books, astronomy hardware and of course a number of meteorites. I was amazed to see the actual number of meteorites that you could purchase, which included rock from the Moon and from Mars.

There were lots of activities for children, including making model craters and the children also received their own iron meteorite for a small fee.

I attended three of the five talks during the day. The first one was by Dr Caroline Smith who was from the Natural History Museum in London, and she looks after nearly 2,000 meteorites in the national collection. We were told that there are over 35,000 meteorites found so far, and that 34,000 of these have come from the Antarctic. The desert of the Antarctic is a great place to find meteorites as they stand out so well in the snow and the dry conditions enhance the preservation of the meteorites, as in a normal country within 20,000 years a meteorite can breakdown and disappear.

We were also told that meteorites can give us the age of the solar system and details on the evolution of the solar system.

It was interesting to find out that stony meteorites are broken down into two groups; achondrites and chondrites. Achondrites have undergone melting whilst Chondrites have not. It was also mentioned that Calcium Aluminium Rich Inclusions (CAI) allow you to date the meteorite.

I also attended a talk entitled “Do you come here often? Dirty snowballs: Comets” by Jonathan Shanklin and a talk by Nik Szymanek, which unfortunately I had seen before, but it was worth sitting through it again, I can’t get bored of seeing Nik’s astrophotography images.

Overall it was a great day, and even better it was all free.

I noticed today that Philips have released a new range of webcams, and there are a couple of Pro models. The main one to look at is the SPC1300 or SPC1330 as it’s called on the Philips web site. The SPC1300 is said to be a 2 Megapixel webcam, unlike the SPC900 which is a 1.3 Megapixel camera.

The major downside of the new SPC1300 is that the sensor is a CMOS sensor where as the SPC900 is a CCD sensor. But will this make a lot of difference when undertaking astrophotography?

Is the SPC1300 the new SPC900? Can the SPC1300 be taken apart and the lens removed and a standard plastic lens adaptor be screwed in? I suppose the only way to find out is to purchase one and try and take it apart.

The cheapest place to buy from seems to be Amazon or Pixmania for around £50.

The weight of the webcam is only 110g and the fixed lens is f/2.8

If anybody has more information on this, or has one and has adapted it, I would love to know about it, so please leave some comments about it.

My first DSLR purchase was a Canon 400D, which I purchased in July 2007, so about 14 months ago. A great camera and the only reason I bought it was to use it for astronomy. But once I heard about the new 450D being released, I thought why not upgrade? Well I left it a while then after hearing a talk be Nik Symanchek I decided to go for it.

I ended up selling my 400D camera on Amazon and then purchased my new Canon 450D from Dixons, for £446 which luckily included a £50 cashback offer from Canon as well as free delivery at the time.

The main reason for the upgrade was the Live View mode, my main problem with doing astrophotography for me was getting the object in focus in the small cameras viewfinder. I did invest in a right angled viewfinder with 2x magnification, but even that was not that easy to use, but it did help.

There is not a great deal of difference cosmetically between the cameras. The menus and layout of the camera are very similar. If you already have a 350d or 400d then you will find using the 450d really easy.

The new 450D is lighter than the 400D, it also has a nice feel to the grip now, with a kind of mottled effect. The 450D now comes with a Image Stabilised lens (IS) which is a nice touch.

On the back of the 450D are the biggest changes, with the buttons moved around in order to accommodate the new slightly larger 3 inch screen.

The Canon battery type has changed and the Compact Flash card slot has been replaced with an SD card, which is useful, as it seems most cameras have now gone back to SD cards, as my HD camcorder also takes SD cards.

The 450D now has 12 mega-pixels instead of the 10 mega-pixels in the 400D.

The Live View mode works in all modes except in Automatic mode, so don’t expect to use the live view just like a compact digital camera. After pressing the “Set” button to enter Live View mode you can zoom in on the object by 5x or 10x magnification, which should help with focusing whilst doing astrophotography. I think you can also get a live view through a PC or laptop, even more useful.

The standard ISO settings are still there. I would have thought we would have seen an ISO setting of 3200 available, but maybe that will be on the next model, 500D? I also think the next model will have 15 megapixels and probably an HD video recording facility. But we will have to wait and see.

Overall the 450D seems worth upgrading to if you really think you need an extra 2 megapixels or the live view mode, otherwise stick with the 400D if you have it. If you don’t have a DSLR then the Canon 450D is a great camera and worth a purchase.

The best price for the Canon 450D Digital SLR Camera seemed to be from either Dixons or Amazon when I was looking.