Dear SpaceTides Subscribers

First of all I will have to apologize for the silence of SpaceTides over the last few weeks. But you don't have to worry - you haven't missed an issue (the last one was #36). The reason for the silence: I am currently working in the USA on a short-term assignment for my audit firm. I am in the Washington DC area, having arrived here mid-October. I am planning to return to SA at the very latest March/April 2006.

SpaceTides will continue as is evident from this issue. Made in the USA, patented in South Africa! The goal is a newsletter once every two weeks, but I can't promise anything. The past few weeks have been hectic with work and sightseeing alike. I'll add an "Educational Astronomy in the US" section so you can follow some of my travels to planetariums and science centres.  This country is totally huge and everything is made to look very impressive.

You will see that we are launching a lucky draw with this issue where you can win a Sky Guide Africa South (3 to give away to three subscribers).  Great astronomical handbooks for the Southern part of Africa, published by ASSA. See section 10.

Hope everyone in SA enjoys their summer! The cold is creeping up on us here and it is not funny believe me.

Thanks for your patience of the past few weeks with SpaceTides, hope you enjoy this issue. Let me know if anyone has any trouble opening the Word documents that I will now use to compile SpaceTides while being in the US.

Gerrit Penning

Editor: SpaceTides Newsletter & member: ASSA Bloemfontein Centre

Total subscribers as at 24 November 2005: 380 (+23 from previous issue, no. 36)
(When the subscriber count reach 400, SpaceTides will be unofficially upgraded to "e-zine status" as compared to an e-newsletter. This thing is sometimes really big and simply being a "newsletter" is in my opinion an understatement! It's not just a "quickly read over tea-break" e-mail anymore, but a "print-it-out and put beside your bed table to read" document!)

Credit: NASA / ESA / A. Bolton (CfA) and the SLACS Team

Einstein Space Ring - gravitational lensing at its best
Harvard Smithsonian CfA press release - 17 November 2005

It almost looks like a planetary nebula, though not quite.
Extract from the above news release: "The thin blue bull's eye pattern surrounding this elliptical galaxy is an "Einstein ring" created by gravitational lensing. Lensing allows astronomers to study the distribution of unseen matter in the intervening galaxies, and to observe light from more distant galaxies that would otherwise remain undetectably faint."  It is "the most elegant manifestation of gravitational lensing".
"Einstein rings are created as the light from galaxies twice as far away is distorted into circular shapes by the gravity of the intervening giant elliptical galaxies".

Article with more info at: http://cfa-www.harvard.edu/previous/latest.html

Larger image at: http://www.cfa.harvard.edu/press/pr0537image.html

Venus: The planet Venus, currently visible in the evening sky after sunset, has such a thick and permanent cloudy atmosphere, that its surface is not visible from orbit (unlike Earth's surface which is so clearly visible in the absence of clouds).  The clouds on Venus consist of sulfuric acid and is almost as reflective as snow (one of the reasons why Venus appears to be so bright).

Geostationary satellites around Earth: "Geostationary satellites" are those satellites positioned at an exact height above the Earth (about 36 000 km). These satellites rotate around the Earth at the same speed as the Earth rotates around its own axis - the satellite thus appears to remain "stationary" above a certain point over Earth.
http://www.sat.dundee.ac.uk/pdusfaq.html

Orbital mechanics, also called "flight mechanics", is the study of the motions of artificial satellites and space vehicles moving under the influence of forces such as gravity, atmospheric drag, thrust, etc. Orbital mechanics is a modern offshoot of celestial mechanics which is the study of the motions of natural celestial bodies such as the moon and planets.
From http://www.braeunig.us/space/orbmech.htm

What exactly is "Cosmology"?
Well, in dictionary terms (www.wordwebonline.com) it is "The metaphysical study of the origin and nature of the universe" and "The branch of astrophysics that studies the origin and evolution and structure of the universe". Make sense? To try and put it simpler: Cosmology studies the Universe on a really large scale. It looks at the properties of the Universe as a whole and endeavors to use scientific methods to understand the origin, evolution and ultimate fate of the entire Universe. It involves a lot of theories and hypothesis like any other scientific field. It's actually quite fascinating (though I haven't really studied it in depth).  You interested? Go to http://map.gsfc.nasa.gov/m_uni.html

How is it possible for a satellite to stay in orbit and constantly move around Earth without using any sort of engine power or remote control?

The following is a very simple way to put it: after a satellite has been shot into space by a rocket, it retains a certain velocity from its rocket launch. While the satellite is in orbit, the Earth's gravity pulls it back.  The satellite's velocity however, is pushing it away into space (outward force = centrifugal force). The two forces "cancels each other out". The rocket is constantly falling back to the Earth (while going in a circle), but does not hit the Earth because it has enough centrifugal/outward force to just resist that pulling force!

Post your astronomy or spaceflight-related question to SpaceTides by sending an e-mail to spacetides@assabfn.co.za

November Planets: Venus shines bright in the evening sky, you cannot miss it! Mercury has disappeared in the Sun's glare. Mars is shining second-brightest after Venus and is visible for most of the evening/night. At midnight it sits high up towards north. Jupiter rises in the morning and is visible just before sunrise in the east. Saturn is also visible in the morning, though it sits much higher in the sky than Jupiter.

November Constellations: For the southern hemisphere observers, the summer is no doubt in full swing, with constellations like Taurus, Orion and Canis Major rising in the east and becoming fully visible in the evenings.  The brightest star visible from Earth - Sirius in Canis Major, will accompany us for the next few months in the sky.

November Deep Sky Objects: Be sure to look at the Pleiades ("Seven Sisters") in Taurus in the north for SA observers. It is also very beautiful through a binocular (the object is too big for most telescopes to appreciate).  The Andromeda Galaxy is now a favourite target for medium to large telescopes - be sure to catch it while it's still on your meridian! Binocular "Power users" should attempt the challenging open clusters of the constellation of Auriga when it's properly situated in your field of view later in the evenings.

Choosing the best eyepieces

Eyepieces are a crucial factor in the overall effectiveness of your telescope's workings. Amateur astronomers will probably agree that buying an expensive telescope and not investing in a good eyepiece can result in the under-utilization of your telescope's true potential.

What eyepieces to select? Usually telescopes come with a set of default eyepieces. If you think you can do better, inquire from someone with knowledge of good eyepieces, read up on the internet and try to borough another eyepiece to fit on your telescope and study the difference. It usually helps to have a range of eyepieces with different focal lengths. Focal lengths? Read on.

Remember that it is not the telescope that magnifies the image, but the eyepiece on the telescope! The smaller the focal length of the eyepiece (e.g. 12 mm compared to 25 mm) the HIGHER the magnification.  To calculate the magnification that your telescope gives, divide the focal length of your telescope by the focal length of the eyepiece. If your telescope's focal length is for instance
2 meters (2 000 mm) and your eyepiece's focal length is 20 mm, the image will be magnified 100 times (2 000/20). Put a 10 mm eyepiece on the same telescope and it magnifies 200 times. (You can find your telescope's focal length in its handbook and the eyepiece's focal length should appear clearly on the eyepiece itself).

So be careful! Some cheap telescope makers will try to fool you into believing that your "telescope" gives a magnification of say 100 to 500 times. This all depends on the eyepiece's focal length. And - putting an eyepiece with a very small focal length on just any telescope may give you the surprise of your life. a constant and aimless struggle to bring the image "into focus". Smaller telescopes need larger eyepieces for a clearer image. Not the greatest magnification, but better clarity at least - a rule of life you will just have to make peace with.  Don't be afraid to invest in good eyepieces - you'll do your telescope (and yourself) a favour!

Visit the South African Space Portal at:
http://www.space.gov.za/

South African Space Portal

Hosted by the National Research Foundation (NRF), the SA Space Portal "has been created by the National Working Group on Space Science and Technology to showcase the contribution of space science and technology to sustainable development in South Africa".

It's no doubt a very "smart" website and SA visitors might find it quite informative. It is also a good source for general school projects on space. http://www.space.gov.za/

This is a site which links to many other space related topics in South Africa.

The Adler Planetarium - Chicago

http://www.adlerplanetarium.org/

The Adler Planetarium and Astronomy Museum in Chicago, Illinois was the first planetarium built in the Western Hemisphere and is the oldest in existence today. The Adler was founded and built in 1930 by the philanthropist Max Adler. It has two advanced planetarium theaters, each taking visitors on a spectacular journey through various astronomical or science-related themes.
Left: The Adler Planetarium. Right: Part of downtown Chicago as seen from the Planetarium. http://en.wikipedia.org/wiki/Adler_Planetarium