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NASA Image of the Day
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| The latest NASA "Image of the Day" image. |
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Snapshot of the International Space Station
On March 13, 2008, the International Space Station passed across the field-of-view of Germany's remote sensing satellite, TerraSAR-X, at a distance of 195 kilometers, or 122 miles, and at a relative speed of 34,540 kilometers per hour, or more than 22,000 mph. In contrast to optical cameras, radar does not 'see' surfaces. Instead, it is much more aware of the edges and corners which bounce back the microwave signal it transmits. Smooth surfaces such as those on the station's solar generators or the radiator panels used to dissipate excess heat, unless directly facing the radar antenna, tend to deflect rather than reflect the radar beam, causing these features to appear on the radar image as dark areas. The radar image of the station therefore looks like a dense collection of bright spots from which the outlines of the space station can be clearly identified. The central element on the station, to which all the modules are docked, has a grid structure that presents a multiplicity of reflecting surfaces to the radar beam, making it readily identifiable. This image has a resolution of about one meter (about 39 inches). In other words, objects can be depicted as discrete units--that is, shown separately--provided that they are at least one meter apart. If they are closer together than that, they tend to merge into a single block on a radar image. Since this image was taken, the station has expanded and is more than 90 percent complete, including a full complement of solar arrays. Image Credit: DLR
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Townsville Astronomy Group
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Written by Lex Howard
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Tuesday, 23 February 2010 22:53 |
MARS – Here We Come???
Our near neighbour Mars (The Rusty Planet) a rich ochre colour very similar to our countries (Australia) west coast and interior in colour and never very large in the eyepiece when viewed from Earth. Best at times like now with opposition just past. Its size varies over the years from around 4 arc/sec to 25 arc/sec at its closest approach to our home world for this year 2010. In January it achieved something like 14.5 arc/sec angular diameter and -2.8 mag.
The little planet begins its celestial show low in the eastern sky and does its ‘jitter bug’ journey across the heavens over a few months only to
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Last Updated on Tuesday, 23 February 2010 23:07 |
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Cleaning your Optical Components |
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Written by Nic Priest
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Sunday, 21 February 2010 23:38 |
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This article is for reflector type telescopes as I have and am only comfortable servicing my Dobsonian.
With lens's if it is only dust on the lens surface itself try blowing lightly on the lens, if no joy a camera blower brush is the next step blowing across the face of the lens the same way you would with a camera lens. If the mark still persists, try cleaning the lens with
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Last Updated on Tuesday, 23 February 2010 22:39 |
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Tuning up a Synta Crayford focuser |
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Written by Vince Legge
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Saturday, 26 December 2009 09:17 |
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Tuning up a Synta Crayford focuser
Most of the earlier standard 2” Crayford focusers as fitted to Skywatcher/Orion and other Synta made scopes have a particular machining fault. Here’s an easy fix. The example pictured is from a refractor, but the same applies to reflectors. If you have one of these its worth taking a close look at it.
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Last Updated on Saturday, 26 December 2009 10:16 |
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Polar Alignment without Polaris |
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Written by Vince Legge
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Saturday, 30 January 2010 15:24 |
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An updated tutorial by Vince Legge
I am referring throughout to the use of a German Equatorial Mount (GEM).
You will need a magnetic compass, one that you can read down to 1° increments, a device for measuring angles, and a little basic handyman skill but we’ll get to that as we work through the technique
Also you will need to determine the Latitude and
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Last Updated on Sunday, 31 January 2010 08:26 |
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Venus, a quick, non complex look |
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Written by Lex
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Thursday, 19 November 2009 23:13 |
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VENUS – A Quick non-complex Look!
Named after the Roman Goddess of Love and our nearest planetary neighbour after our own natural satellite the Moon, it orbits at a mean distance of around 108 million kilometres from the Sun.
The ancients saw Venus as a paradise, the home of the Goddess of Love and beauty etc. Some had it as a place of opulence with lush botanical growth and huge expanses of water filled swamp land, while others saw it as a vast desert (dune like) setting with large mountains and valleys.
The folk in highplaces and of different cultures
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Last Updated on Thursday, 19 November 2009 23:34 |
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Latest Posts
 in Events Discussion by Liz, 11-03-10 09:19
 in Event Listings by zebra1707, 01-03-10 17:52
 in Planets by Liz, 01-03-10 12:59
 in Event Listings by Liz, 28-02-10 14:40
 in Open Discussion by nicpadre, 27-02-10 02:33
 in Event Listings by zebra1707, 26-02-10 22:39
 in Open Discussion by Vinnie, 25-02-10 09:08
 in Open Discussion by Lex, 24-02-10 19:45
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