The glass mirror of Hubble Space Telescope
Glass is extremely difficult and mysterious material. It is hard to achieve the color you want, almost impossible to completely stabilize it after firing, difficult to polish it and so easy to break it. In fact, nobody really knows the best firing schedule for any kind of glass yet. Everyone fires and anneals glass just by experience and guess.
Here is the story of Hubble Space Telescope. According to this story, the most crucial and complex part of making this telescope was the mirror and optical systems. The glass mirror of Hubble was made in an enormous kiln. For firing glass, I use kilns with at most two square meters. The kiln used for the Hubble mirror would have been the size of a large room. As I wrote above, polishing glass is quite difficult, too. If polishing manually, it demands a lot of time, energy, accuracy and patience. Hubble mirror was polished by computer, but still it could not achieve the required accuracy.
After investing massive amount of effort and money, Hubble Space Telescope finally started sending images such as these. The following pictures are some of the top ten most amazing pictures taken by Hubble in last 16 years selected by astronomers.
“…they illustrate that our universe is not only deeply strange, but also almost impossibly beautiful.” Michael Hanlon/AH (Nov 25th, 2006)
Talking about our universe, there was a total solar eclipse on 1 August. Next year, it will be seen again on 22 July in Japan, too. I have seen one on 11 August 1999 at Lake Balaton in Hungary. “Diamond Ring” was incredibly beautiful and the darkness caused by the solar eclipse indeed let us imagine the end of the world.