Brian W
01-04-2010, 06:20 PM
Hi all, I have recently downloaded G.F. Chambers book entitled 'Astronomy' which was written circa 1910. In it he deals with onbservations that someone with a 3 to 4 inch telescope can make. He goes into the history and he includes sketches as well as photos.
Below is a small exerpt from his section on Saturn. If this is the sort of thing that is of interest I can certainly upload more of his book. Conversely a simple web search will allow anyone to download the whole book.
Brian
SATURN.
There are probably very few people who have any knowledge
of anything scientific who have never heard of Saturn and
its ring. The planet, though inferior in lustre to Mars and
Jupiter, is always to be found without difficulty when in a dark sky, shining, as it does, like a star of the second or third Magnitude. It compares, however, unfavourably with its rivals because it has a dull, leaden hue.
Though its appendage is often spoken of as "the Ring,"
using the word in the singular number, yet it is really a system of rings which surrounds the planet, and the number grows with the size of the telescope used to scrutinise it. Whilst a small telescope will only show one ring, a larger one will show this one divided into two ; a still larger one will show the outermost of the two again divided into two. In addition to these there is a third main ring, which is the innermost of all. Unlike the rings just spoken of, this innermost ring is not bright, but dusky ; and the name originally given to it on its discovery, rather more than half a century ago, of the " crape ring," has not quite fallen into disuse, and is not altogether
inappropriate.
The history of the discovery of this ring is rather curious,
and suggests a mysterious origin and developement of it. In
1838 a distinguished German astronomer, J. G. Galle, pub-
lished an observation in which he said he had noticed a
shading-off of the innermost bright ring towards the planet.
His remark seems not to have attracted any particular notice
until 1850, when G. P. Bond in America, and Dawes in Eng-
land, independently discovered the dusky ring, and recognised
it distinctly to be a ring, but transparent in so far that the body of the planet could be seen through it.
This dusky ring is now a recognised feature of Saturn, and
it would seem to be wider and more easily visible than for-
92 THE MOST INTERESTING AND FAMILIAR PLANETS.
merly, and a division of the dusky ring into two rings has been suspected. The germs of its discovery are to be seen in Galle's note of 1838 ; whence, perhaps, it is permissible to suggest that the ring has gone through stages of developement during the last three-quarters of a century. There is no trace in the writings of either of the Herschels of their having detected any traces of a ring inside the innermost bright one, though it must be confessed that Picard in 1673, an< ^ Hadley in 1723, saw something which might perchance be identifiable with the dusky ring of the observers of the igth century.
Saturn and its system, treated as a whole, is not only a very
remarkable and interesting object, regarded as a spectacle, but every 30 years undergoes interesting transformations which must now be described. For convenience of reference it is customary to call the outermost bright ring A, the innermost bright ring B, and the dusky ring C.
Figs. 136-137 show the interior edge of the crape ring as
drawn in March 1888 by J. G. E. Elger. The irregularities
are very noteworthy, but I am not aware that they have ever
been confirmed ; at any rate, in anything like the form
suggested by Elger.
Though under ordinary circumstances that is to say, during
a considerable succession of years we see Saturn as a ball
surrounded by its rings, yet, owing to the orbit of Saturn being inclined to the plane of the Ecliptic, we see the rings at inter- vals either opened out very wide or not opened out at all, but presented edgeways.
Perhaps this will be made a little more clear by giving some
dates. In 1907 the Earth was in the plane of the rings ; they
were more or less invisible for a short time (October 1907
January 1908), being placed edgeways to the view of us on the
Earth. In 1907 the Sun began to illuminate the southern side
of the rings, after having for 14! years shone upon the northern side.
Brian
Below is a small exerpt from his section on Saturn. If this is the sort of thing that is of interest I can certainly upload more of his book. Conversely a simple web search will allow anyone to download the whole book.
Brian
SATURN.
There are probably very few people who have any knowledge
of anything scientific who have never heard of Saturn and
its ring. The planet, though inferior in lustre to Mars and
Jupiter, is always to be found without difficulty when in a dark sky, shining, as it does, like a star of the second or third Magnitude. It compares, however, unfavourably with its rivals because it has a dull, leaden hue.
Though its appendage is often spoken of as "the Ring,"
using the word in the singular number, yet it is really a system of rings which surrounds the planet, and the number grows with the size of the telescope used to scrutinise it. Whilst a small telescope will only show one ring, a larger one will show this one divided into two ; a still larger one will show the outermost of the two again divided into two. In addition to these there is a third main ring, which is the innermost of all. Unlike the rings just spoken of, this innermost ring is not bright, but dusky ; and the name originally given to it on its discovery, rather more than half a century ago, of the " crape ring," has not quite fallen into disuse, and is not altogether
inappropriate.
The history of the discovery of this ring is rather curious,
and suggests a mysterious origin and developement of it. In
1838 a distinguished German astronomer, J. G. Galle, pub-
lished an observation in which he said he had noticed a
shading-off of the innermost bright ring towards the planet.
His remark seems not to have attracted any particular notice
until 1850, when G. P. Bond in America, and Dawes in Eng-
land, independently discovered the dusky ring, and recognised
it distinctly to be a ring, but transparent in so far that the body of the planet could be seen through it.
This dusky ring is now a recognised feature of Saturn, and
it would seem to be wider and more easily visible than for-
92 THE MOST INTERESTING AND FAMILIAR PLANETS.
merly, and a division of the dusky ring into two rings has been suspected. The germs of its discovery are to be seen in Galle's note of 1838 ; whence, perhaps, it is permissible to suggest that the ring has gone through stages of developement during the last three-quarters of a century. There is no trace in the writings of either of the Herschels of their having detected any traces of a ring inside the innermost bright one, though it must be confessed that Picard in 1673, an< ^ Hadley in 1723, saw something which might perchance be identifiable with the dusky ring of the observers of the igth century.
Saturn and its system, treated as a whole, is not only a very
remarkable and interesting object, regarded as a spectacle, but every 30 years undergoes interesting transformations which must now be described. For convenience of reference it is customary to call the outermost bright ring A, the innermost bright ring B, and the dusky ring C.
Figs. 136-137 show the interior edge of the crape ring as
drawn in March 1888 by J. G. E. Elger. The irregularities
are very noteworthy, but I am not aware that they have ever
been confirmed ; at any rate, in anything like the form
suggested by Elger.
Though under ordinary circumstances that is to say, during
a considerable succession of years we see Saturn as a ball
surrounded by its rings, yet, owing to the orbit of Saturn being inclined to the plane of the Ecliptic, we see the rings at inter- vals either opened out very wide or not opened out at all, but presented edgeways.
Perhaps this will be made a little more clear by giving some
dates. In 1907 the Earth was in the plane of the rings ; they
were more or less invisible for a short time (October 1907
January 1908), being placed edgeways to the view of us on the
Earth. In 1907 the Sun began to illuminate the southern side
of the rings, after having for 14! years shone upon the northern side.
Brian