A little ramble through 19th century astronomy - satellites of Saturn in 1875

 Academy, Saturday 17^th July 1875

Satellites of Saturn.—ln the Astronomische Nachrichten, No. 2043, Mr. Marth gives an ephemeris of the satellites of Saturn, which will greatly facilitate observations of these objects, as they are very liable to be confused with small stars in the neighbourhood.

There is considerable uncertainty about the positions of the innermost satellite Mimas and the outermost lapetus, and no ephemeris is given for Hyperion, the last discovered, as trustworthy observations are wanting for this satellite. The places of the other five are tolerably correct, but observations are much wanted of this extremely interesting system about which so little is known, the mutual perturbations of the satellites and the effect of the ring being most important questions, which can only be solved by accumulated observations.

 With the view of facilitating these, Mr, Marth has given the approximate times of conjunction of the several satellites with the planet. Eclipses, occultations, and transits only occur when the earth is nearly in the plane of the ring (every fifteen years), except in the case of Titan, whose orbit is considerably inclined to the ring.

                                                      www.theramblingastronomer.co.uk

A little ramble through Leo Minor the Lesser Lion

 The smaller Lion designated by Johannes Hevelius in 1687, located between Ursa Major and Leo. Leo Minor hardly merits a separate name as there are no bright stars. He designed 10 new constellations, and we still use 7 of them today.

There are some suggestions that the stars that form Leo Minor were once identified by the Arab astronomers as Al Thiba wa-Auladuha or the Gazelle and her young.

The brightest star is 46 Leo Minoris with a magnitude of 3.8, its an orange K class giant star lying at a distance of 95 light years.

                                                       www.theramblingastronomer.co.uk

Cooke Telescope Tales - John Robertson of Coupar Angus 1830-1920

 John Robertson of Coupar Angus 1830-1920 owned a fine Thomas Cooke of York 3 inch refractor telescope. His interest in astronomy began in 1848 when he heard Dr Thomas Dick give a series of astronomical lectures.

 He spent many hours observing the sky, including sunspot observations and comets and meteors.  He was self educated and he had to fit all his observations of the sky around his work. He was employed by the Caledonian Railway. 

He sent many articles to newspapers including the Scotsman and some of the Dundee Daily newspapers. Among the astronomers he correspond with were Sir W.H. M. Christie, Richard A Proctor, Sir Robert Ball and Ralph Copeland. 

He was still using the 3 inch Cooke telescope as late as August 1917 to observe sunspots, with his advanced age his daughter had to help move and adjust the telescope.

                                                      www.theramblingastronomer.co.uk

A little ramble through 19th century astronomy - Stars, Saturn and photographs

 Academy, Saturday 19^th June 1875

 

Royal Astronomical Society (Friday, June 11). Professor Adams, President, in the Chair.

A paper by Mr. Knobel was read, giving some results of measures of magnitudes of stars with his astrometer, described in a previous paper, the principle of the instrument being to reduce the aperture of the telescope by means of a variable triangular diaphragm till the star disappeared. Mr.Knobel  pointed out several discordances between his results and the magnitudes given by Argelander in his Uranometria, though those of the Bonn Durchmusterung agreed better.

 Mr, Marth called attention to approaching phenomena of the satellites of Saturn, the most important of which, however (those of Titan), would only be visible in Australia and in the United States, the period of revolution being very nearly sixteen sidereal days, so that occultations and transits of this satellite would take place at the same sidereal hour for many successive periods, and at these times Saturn would be below our horizon. Mr. Marth expressed a hope that the great Melbourne reflector might be used for these observations, and Mr. Russell promised that he would employ the 11-inch refractor of the Sydney Observatory for this purpose.

 Captain Abney, R.E., gave a description of his Diaphanometer, an instrument which he had devised primarily for measuring the opacity of photographic films after exposure to light under different conditions, and which he had since applied to other questions in photometry. In this instrument the collodion film was compared with a graduated wedge of smoke-coloured glass. Captain Abney also exhibited an ingenious form of spectroscope in which the brightness of any part of the spectrum of a star could be compared with that of the spectrum of a standard source of light, the two spectra being brought one above the other in the same field by means of reflection prisms.

Some other short papers of a purely technical character followed, after which a note by Mr. Proctor on “ Photography in the Transit of Venus” was read, to which Mr. Russell, Mr. De La Rue, and Mr. Christie replied, and Mr. Neison mentioned, as bearing on the question of the atmosphere of Venus (which  Mr Proctor had incidentally  referred to), that Professor Lymans had observed Venus as a bright ring five hours before the commencement of the late transit.

                                                     www.theramblingatsronomer.co.uk

Cooke Telescope Tales - transit of Mercury observed in 1878 from Peeblesshire

Robert Mathison of Innerleithen Peeblesshire observed the Transit of Mercury on May 6^th 1878 using a Thomas Cooke of York 4.1 inch telescope. 

The transit was seen from the ‘observatory’ no trace of the planet could be seen outside the disk of the Sun. A small group of sunspots were seen on the Sun close to the planet at 4.40 pm. 

One point that caught the attention of Mathison was that a bright white point of light which he followed until 5.30 pm when the Sun was covered by clouds. Other observers at this location confirmed the sighting of the bright white spot.

                                                      www.theramblingastronomer.co.uk

Cooke Telescope Tales - sunspots observed from Thornton in Craven in early 1860s

On December 14^th 1864 Thomas Wilson of Thornton in Craven using a 4.25 inch Thomas Cooke & Sons telescope observed a solitary spot on the surface of the Sun. He says that in sketching the spot immediately after apparent noon, finding the penumbral outline and radial shading considerably confused and indistinct, especially on the eastern side, my attention was drawn to its surrounding neighbourhood, where I was agreeably surprised by the realisation of the elongated very minute lenticular forms, which have been compared to willow leaves, overlapping the penumbra and, and diffused over the whole surface. 

Wilson goes onto say that in making 97 sketches of spots during the last three and a half years, nearly all after taking meridian transits, I never before saw anything beyond the mottled surface, which has been described as parchment, rice grain,  flocculent chemical precipitate like appearances &; I have supposed that depending on the state of the air this was beyond the reach of a small telescope such as my 4.25 inch Cooke.

                                                      www.theramblingastronomer.co.uk

The Astronomy Show on Drystone Radio

 Join me, Martin Lunn MBE every Monday evening from 7.00 pm-9.00 pm on the award-winning Astronomy Show on Drystone Radio, probably the only regular astronomy show on any radio station in the country. 

I will take my weekly look at the night sky and look at all the latest news in astronomy. There will be the astronomical anniversaries this week plus the latest news from the astronomical societies in the north of England.

 

The Astronomy Show every Monday evening only on Drystone Radio live online at www.drystoneradio.com DAB radio in Bradford and East Lancashire, or 102 and 103.5 FM and can also be heard later on the Drystone Radio Podcast.