Not relativity with a capital R.

cheers for watching

yes, seven years bad luck would not be enough in this case!

DeepSkyVideos I guess 70 years in jail.

Peleg Tsadok I guess ther could be somethings else but JAIL,,, cleaning the whole thing after you broke it... including all the fine corners and machines... while being watched from behind by angry and pissed of scientists :P

I think you're already unlucky if you tried to break that mirror. Lol

I'm sure there are suppliers of such things. If all else fails you could try to make your own.

Make your own, it's not very hard - I ground and figured a 12" F5.5 out of a piece of ships portal glass when I was 15 years old - so anyone can do it. I would recommend "how to make a telescope" by Jene Texereau, its a really old book well out of copyright, and you can download it as a PDF off the internet, just do a search. Also join your local astronomical society, they are bound to have some people who grind their own mirrors who will be able to help you find the equipment and consumables you need - the only difficult stuff to get hold of is the pitch, the carborundum and the aluminium oxide or rouge for polishing, and of course a suitable blank.

You could try Orion optics. They sell mirror sets.

rocklobstersteve Thanks.

Rouge planets? So, Mars?

No...planets without a parent star -.-

H34dHun734R Oh, you must mean rogue planets, then.

I feel more sad, you can at least go someday! I am to far away!

here is our visit to the E-ELT site: Extremely Large Telescope - Deep Sky Videos

Oh man how did I miss that one? Thanks!

not in significant enough matter as it is on the primary mirror If you put a finger right before a long telephoto lens (300mm for 56mm film) you'll notice the image only getting a bit darker, but you won't see even an outline of the finger.

Ah ok! Well I was just thinking that such an expensive mirror would have been kept clean :P

When dealing with such large scale structures for measuring immense distances, reflectivity is only a single property that must be considered. Stability for a mirror to hold its shape, temperature sensitivity, minimum movement between slight temperature changes and even the cost of the material. It would be interesting to know why they chose the material for each mirror and why they didn't use other materials.

No, in the visible, aluminium reflects best, when it is properly coated.

I am fairly sure, but not positive, that silver reflects more light than aluminum, although aluminum is not much less. Silver is not used on first-surface mirrors (where light is reflected before passing through another material, such as glass) because it oxidizes to a black, not reflective, and not very transparent, compound so quickly. The surface of all metals oxidizes in a matter of minutes, but some, such as aluminum, are translucent and thin. The oxide of aluminum is the same clear material, minus the color, as the gemstones ruby and sapphire.

When it is a monocrystal, aluminum oxide is indeed a clear and transparent material. But the oxide layer you get by exposing metallic aluminum to air is not! it is made of many nanometer-sized crystals which cause a lot of diffusion of the light. That is why aluminum first surface mirrors always have an aditionnal coating on top of aluminum, made of Titanium dioxide and Silicon dioxide. meade.com/catalog/uhtc/ And it seems you were right about silver's reflectivity.

I've been told Aluminium has better sensitivity in the blue while Silver has better sensitivity in the red. Gemini has a silver coating for this purpose.

Hi: Instead of buying a scope for now. Go on the net and look around to see the scopes the are online. I know of one down in Southern Arizona near Green Valley. I have forgotten the name of the (Mount Hopkins) mountain with lots of scopes on top. If you do buy; look around for some Astronomy Clubs in your area. Talk to experts; they were where you are now long ago. Good Luck. If you are ever end up in Tucson AZ. go to see Kit Peak out side of Tucson; simple tours are available.

Thanks for the reply, I did see a club here in Indiana. I will definitely check out the online scope. My wife wants me to hold off again on buying one. Which is understandable since we have a newborn baby and we are looking to buy a house. Eventually I'll get it. :)

4 years later, have you gotten a telescope and if so, which one? :)

I was wondering the same thing, though given how dirty it is, maybe they aren't lol