gary
23-12-2012, 06:10 PM
You have to feel sorry for those whose birthdays happen to fall on 25 December.
More often than not, the celebration of their birthday is eclipsed by other festivities.
However, this 25 December marks a special occasion for all astronomers,
as it celebrates the 370th anniversary of the birth of the creator (http://en.wikipedia.org/wiki/Isaac_Newton) of the Newtonian
reflecting telescope (http://en.wikipedia.org/wiki/Newtonian_telescope).
Galileo died on January 8th, 1642 and somewhat fittingly Newton was born
in that very same year.
At the age of 25 in late 1668, Newton constructed the first known reflecting telescope.
Earlier, Newton had performed his celebrated work on optics and the theory of colours.
Newton had observed that refracting telescopes at the time suffered from
chromatic aberration. If you study the edge of a lens, you will notice it forms
a little prism. He had theorized that a reflecting telescope would be free of
this defect and his first reflector employed a a spherical speculum metal mirror
and was a 1.3" f/5. He used it to make observations of the Galilean moons and of
the phases of Venus.
In 1671, a second reflector was presented to the Royal Society and demonstrated
to Charles II in 1672. Newton was then admitted as fellow to the Society.
A replica of that second telescope can be seen in this image here -
http://upload.wikimedia.org/wikipedia/commons/c/cc/NewtonsTelescopeReplica.jpg
As a telescope, its purpose and function is instantly recognizable to any
amateur astronomer today.
So this 25th December, be sure to go out and pat your faithful Dob and spare
a thought for that genius of geniuses that conceived and built the very first
reflecting telescope.
More often than not, the celebration of their birthday is eclipsed by other festivities.
However, this 25 December marks a special occasion for all astronomers,
as it celebrates the 370th anniversary of the birth of the creator (http://en.wikipedia.org/wiki/Isaac_Newton) of the Newtonian
reflecting telescope (http://en.wikipedia.org/wiki/Newtonian_telescope).
Galileo died on January 8th, 1642 and somewhat fittingly Newton was born
in that very same year.
At the age of 25 in late 1668, Newton constructed the first known reflecting telescope.
Earlier, Newton had performed his celebrated work on optics and the theory of colours.
Newton had observed that refracting telescopes at the time suffered from
chromatic aberration. If you study the edge of a lens, you will notice it forms
a little prism. He had theorized that a reflecting telescope would be free of
this defect and his first reflector employed a a spherical speculum metal mirror
and was a 1.3" f/5. He used it to make observations of the Galilean moons and of
the phases of Venus.
In 1671, a second reflector was presented to the Royal Society and demonstrated
to Charles II in 1672. Newton was then admitted as fellow to the Society.
A replica of that second telescope can be seen in this image here -
http://upload.wikimedia.org/wikipedia/commons/c/cc/NewtonsTelescopeReplica.jpg
As a telescope, its purpose and function is instantly recognizable to any
amateur astronomer today.
So this 25th December, be sure to go out and pat your faithful Dob and spare
a thought for that genius of geniuses that conceived and built the very first
reflecting telescope.