Posted on Thursday, December 08, 2016
By Kadri
This week I had the chance to use a Zeiss refractor for observing and photographing the Moon and Venus.
The refractor in question is an old and big one, namely it's from 1911 and it has a 20cm objective lens and a focal length of 3 meters.
It's housed in a historic observatory, where the telescope tower is moved manually, the observation slit's hatch-doors are also opened and closed manually, etc. Oh, it also has a clock drive, which can keep up with stars for an hour or so without having to be wound up again.
I have observed some planets, and the Moon on several occasions with it before, but I've never been able to find the object, focus it, take pictures etc, on my own.

So my first impressions of it - first off I found just getting to the eyepiece quite a challenge, as the Moon and Venus as well were low in the sky, so the stepladders that are there were of great use, but also quite cumbersome - they're of different heights and weights, and I found that if I get the ladder in the proper position to observe though the main telescope, then I could only barely reach the guide scope (which couldn't reach sharp focus - I wonder why?).

Now another thing was, that as soon as I got my DSLR attached to the telescope, the image through it, although being larger than with my normal setup, looked really lousy - in part because of the atmosphere and bad seeing, and low fast moving clouds, and also because of me totally forgetting that this telescope also has a fine focusing screw - I kept only using the rough focusing ring!

The pictures I obtained however weren't that good in my view - the image of the Moon just wasn't as sharp as I've grown used to with a 1 meter focal length 10cm aperture refractor - really not worth it, unless I'd be on the lookout for something else, a specific crater perhaps, using eyepiece projection etc.  Maybe it'll just take time to get used to the kind of setup, where you're afraid to step somewhere and find the stepladder doesn't go that far, or find that an eyepiece or adapter has started rolling and wants to fall to the floor from the height of 2m.
I did see Venus through the telescope as well, but couldn't find it after attaching the camera, probably because the clock-drive had stopped by the time I had found Venus, which took about half an hour or so, partly because it was mostly behind clouds, and partly because the telescope had to be rotated from one side of the mount to the other side...
And the image of the Moon in the previous post was taken with that telescope in main focus with a Canon EOS 500D.

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Posted on Thursday, December 08, 2016
By Kadri
Part of the Moon on December 6th, 2016. Credit: Kadri Tinn

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Posted on Thursday, December 08, 2016
By Kadri
The Moon on November 9th, 2016. Credit: Kadri Tinn

The Moon as seen through clouds on November 9th, 2016. Credit: Kadri Tinn

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Posted on Friday, October 28, 2016
By Kadri

Future Spacecraft Propulsion Systems: Enabling Technologies for Space Exploration by Paul A. Czysz and Claudio Bruno

If you've ever tried to imagine just a generic rocket and how it works or wondered whether there is any theoretical or practical way how spacecraft might some day go a lot further in a shorter period of time than they do now, then this thorough book is the one to peruse.

Future Spacecraft Propulsion Systems talks about the different possible propulsion systems, some of which are in use now, or are being tested and some that might become possible in the future. In addition to the details, calculations and analyses of the benefits and problems of various systems, there's also talk about exploring the Universe at different scales and distances by going there - would it ever be possible to see the Andromeda Galaxy from closeby? What are the difficulties of such exploration and how could they ever be overcome?

The book is interesting in both the technical details and overviews but also in the theoretical parts where it for example explores Special Relativity and the nature of time, but also how it might be possible to travel through a black hole. It's very fascinating, as the language used in the book is similar to what you would hear in a science fiction film - talking about jumps to hyperspace, going into a mild black hole etc.

In general it's an excellent and very useful book when you're interested in technology and physics, or when you want to find out more about some of the ideas that modern science fiction books and movies use. It's also a great first longer introduction into some specific propulsion methods and proposed spacecraft designs.

Successfully reading this book requires a bit of background knowledge about some of the topics in the book.


Posted on Friday, October 28, 2016
By Kadri
Posted on Thursday, October 06, 2016
By Kadri
Making Starships and Stargates: The Science of Interstellar Transport and Absurdly Benign Wormholes by James F. Woodward

The topic of travelling through wormholes and stargates and travelling quickly to interstellar distances had probably interested anyone who has ever watched Sci-fi series or movies where those concepts are used. Because the topic is so widely used in pop culture I feel like there are tens of books that deal with starships etc. 

What makes this book special? The author looks into published scientific papers in those topics on the possibility of travel at light-speed using different methods, looking into the physics and mathematics there etc. How might it be possible? Which laws of nature seem to forbid such travel? You can read all about that and much more in this book. 

The book is highly technical, very detailed and you do need some higher maths and  quite a lot of motivation to work through it. 
If you find though that it's a little too difficult, then the book also has excellent bibliography which can guide you either in the more popular books direction or to some more technical books.

I found that it was interesting, well written and followed a logical structure  so you see how the different principles and concepts are all necessary for it.


Posted on Monday, October 03, 2016
By Kadri

Venus and the Moon. To find Venus look to the left edge below the cloud band above which the Moon sits . Credit: Kadri Tinn

Venus on October 3rd, 2016. Credit: Kadri Tinn

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