Story Of The Telescope Chapter 1

Prior to the time of the telescope, man's view of the celestial universe was woefully restricted when compared with what now can be enjoyed on any clear evening with ordinary binoculars.

There were visible to him then only the naked-eye objects, the sun and the moon, five of the planets, and on a clear night stars down to about the 6th magnitude, some 2,000 in all.

 A few hazy spots could also be seen, and there would be an occasional comet. Completely unknown were the outer planets, satellites of the planets, Saturn's rings, and infinite numbers of stars and galaxies.

Yet, working without optical aid, early observers managed to make some amazingly accurate charts of the visible stars, and amassed the observations from which the laws of planetary motion were deduced.

The principal instrument used in establishing star and planet positions was the quadrant, a device having a graduated arc, and a pointer that pivoted about its center. With it Tycho Brahe (1546-1601), Danish astronomer, and one of the keenest of all observers, was able to record the positions of stars to within
one minute of arc — about 1/30 the diameter of the moon. This

!There are about 6,000 stars in the sky that are bright enough to be visible to
the average eye, but about half this number is contained in the celestial hemi-
sphere that is below the horizon. Atmospheric haze obscures the fainter stars
lying close to the horizon, thus reducing the number visible at any one time
to about 2,000. Some authorities place the figure at 2,500.

was an amazing feat, when it is considered that one minute of arc is about the limit of visual acuity.

Then, in 608, seven years after Tycho's death, the telescope was brought upon the scene by a Dutch spectacle maker, Jan Lippershey  to whom its invention is credited. The invention marked one of the great progressive triumphs of man, enabling him to reach farther and ever farther out into space.

It was not much of a telescope, this first refractor, consisting of two spectacle lenses perhaps an inch in diameter, one convex and the other concave, and magnifying possibly two or three times. Lippershey, whose name historians
spell in various ways, managed to combine two such instruments into a unit, and thus also made the first binocular telescope.

Galilean Telescope