Why Are Telescope Mirrors Made Of Glass?
Tuesday, December 1st, 2009 at
8:31 pm
And are they just not made of a metal since glass mirrors are finish with metals.
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US $29.99
Glass is more dimensionally stable – it doesn’t expand or contract when the temperature changes – and it can be polished to a very smooth surface. The finish is a very very thin layer of metal.
Read “The Perfect Machine” by Ronald Florence if you want to learn more.
Telescope mirrors are highly polished concave lenses with a thin metal lining on the back side. They are “concave” on one side, flat on the bottom side. Concave is thin in the middle and thick around the edges. Metal would contract and expand as temperature changes so therefore would not be of value in observing. The “Pyrex” glass of telescopes resists these temperature changes so is a readily stable medium. The largest single mirror in the USA is the Palomar Observatory. It has a mirror 200 inches across. We do have a multi morro scope that gives the impression that it is larger but it has more than one mirror. Six I believe. The 236 in mirror in Russia is the worlds largest single mirror. Except for the curvature of the earth, if a candle was lit on the sidewalks of London, Palomar could see it.
may be because glass reflects better
we need to teach the mystery and enoromity of space in school to galvanise peoples priorities and perspective of what we are and why we are here.. and the way we should treat people.. that is a logical and certainly a major priority in getting us all to live in peace.. so we can concentrate on whats really important our survival and the survival of our children
Okay, seal the telescope with PVA then paint it and varnish it. 8D
whens number 2 coming out?
omg this song is soo wonderful
If you are talking about chocolate dipped truffles, and not just chocolate ganache rolled into balls, then the following will help. If you are talking about simple rolled ganache truffles, then don't worry about it. They will last almost indefinitely in the refrigerator. Just roll them in whatever you are coating them with at the last minute. You could even make the ganache balls way in advance and freeze them, then thaw in the refrigerator and on the day of the wedding roll them in different powders like powdered sugar, cocoa powder, chili powder, cinnamon, etc.
For chocolate DIPPED truffles:
If you have an area in your home where the temperature is pretty constant, and does not get hot at ALL, then 2 months is no big deal for truffles.
You need a room temperature storage area (About 74 degF) and you never want to get them up into the 80 degree F or above temperature range.
If you try to store them in the refrigerator, the moisture in the air will condense on the chocolate when you take them out, and your chocolate will absorb the water.
If you have refrigerator space, then you CAN use it to store truffles. But you have to be careful how you handle them.
First of all, you want to put them in boxes and wrap them several times with plastic wrap, and make sure the boxes are as small as the truffles can handle.
Then, when you want to bring them up to room temperature, you need to temper them as SLOWLY as possible, keeping them in the box and wrapped at all times. Move them into your basement first, or raise the temperature of your refrigerator slowly. Then move them into the coolest place of your home. You don't want the shock of "cold to hot" to cause condensation on the chocolate.
That's about all I know. Good luck!
Try it with a small batch before you try it with the big batch.
la mujer mas bella de los 70’s!!!!
I gotta try this.
u made them happy kiki wouldnt sleep tonight that's cute
LOL, same here, Mona. I feel really bad whenever I stay home.
the only difference is that most of you are broke ,looking for the American dream that you don’t even know what that shit is.they learned you that beung broke is happiness and you beleive them.this is america.the richest country of the world on war equipment with the poorest people.
i love you shane x] the new vid made me die laughing
"A person who never made a mistake never tried anything new." Try something new. ..
I don’t even have it in gmail yet but I just got a “Buzz from Louis Gray” and a link to this public page Looks like Reader promotes ALL comments to public..
Blame it on the Koala’s
With brightly red colors, crystal clear and transparent posture; when it is poured into a glass, the fruity smell and unique wine flavor as well as the composition determine its most suitable for table drink. Refer to researcher, red wine increases the levels of appetite-stimulant, hormone leptin in females, but not in males.
Jamie says “Duh… isn’t that fairly obvious?” I think she is lying.
katılmamak elde değil sanki romence yazıyor o ekranlar yarım saat ekrana bönbön bakanlar yokmu
Raffiche di Vento ＞hi!….superlike?….wow!….^0^
You have a wide variety of telescopes to choose from for under $1,000, however, you have a wider variety if you buy a used telescope.
You want a reputable brand such as Meade, Orion, Celestron, Takahashi, TeleVue, TEC and the likes. The telescope must have a stable mount and have tracking abilities. Goto isn't needed though.
An equatorial mount is preferred for astrophotography but many Schmidt Cassegrains come standard on fork mounts. This is fine if you buy a wedge and a field de-rotator.
Most people are very well suited with 8" Schmidt Cassegrains. You can buy these used for under $1000, often with accessories, on places like and
You can try eBay as well.
well remember they lost a piece for the drum .. cause damari thought it was a piece to his telescope !
Is it possible to reach the mounting tape? I know that either
wd 40 or Pam sprayed on sticky stuff will help it release.
Sorry this is my best suggestion. I would use a putty knife, it should do the least damage.
I used these once and was very sorry too. Good Luck
“If Nemesis exists, it may not be close enough to influence our sun very much; there are some interesting planet changing events that seem to occur in cycles…maybe that telescope can help answer some of those questions”
= tea, Philip Glass and Patten's 'George Cruikshank: Life, Times, and Art' = the life.
I would say that vinyl is the most common, with teflon being pretty rare. THere are other coatings, such as polyimide varnishes, polyethylene, etc.
Ultimately they are all made from oil, plus some other resources, such as fluorite rock for teflon.
LH: Sea Gull Lighting 4060-05 Blakely Four-Light Vanity, Chrome Finish with Etched Faceted Glass
Reminds me of Interview with the Vampire (book) because I was listening to this when I finished it
Amazing book and amazing film (one of the few adaptations that isn’t utterly crap)
NASA’s newest space telescope, the $230 million Wide-field Infrared Survey Explorer (WISE), has been busy discovering hundreds of asteroids every single day–all of which were in our solar system undetected all this time.
i seriously dont think u should be driving either