The M.A.S. Newsletter
Journal of the Mauritius Astronomical Society
November 97
Meeting:
The last meeting of the year will be due on Friday 28th of November 1997 at 7hr30 pm at the St Esprit College, Quatre Bornes.
ACTIVITY:
Observation of the planet Saturn. Members will be informed about the January meeting.
NOTE:
The closing date to order photographs of recent lunar eclipse is the 28th of November.
The planet Saturn:
The most spectacular among the planets, Saturn is the most distant observable with some details through the C-8 telescope. It is now at a distance of roughly 1.3 billion kilometres. Nevertheless, the glorious ring system together with the shadow of the planet cast onto it and dark bands across the planet can easily be seen. If we do not let our eyes be distracted by the rings, we might as well notice that Saturn is the most flattened of the planets. It spins round so fast (10 hours, 40 minutes), that this causes it to bulge out at its equator. Thus, it would take eight and a half Earths to stretch across the planet from pole to pole, while the distance across its equator amounts to nine and a half Earths! Saturn is second in size only to Jupiter. Its average density is so low that it would float on a large enough ocean! From Saturn's density and flattening, astronomers have worked out what is inside the planet. In the centre is a liquid-rock core several times the mass of the Earth, on top of which is liquid hydrogen under such high pressure that it conducts electricity like a metal. Next comes a thick layer of ordinary liquid hydrogen, mixed with helium and finally a thin veneer of atmosphere.
The Magellanic clouds:
In this period of the year, when the Southern Cross and both a and b Centauri are not visible, one might think that we cannot find the south and therefore are lost! Not quite! We still have the two Magellanic clouds. On a clear moonless night, these two 'clouds' can be seen hanging to the southern sky. These are the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC): the nearest visible galaxies at distances of about 169,000 and 210,000 light years respectively. By placing the Malleganic clouds at two of the vertices of an equilateral triangle, the third vertex nearest to the horizon is the south celestial pole. Now, dropping a vertical line from this point brings you to the south (geographical).
The sky this month:
Also visible in the sky this month is the Andromeda galaxy - M31. At a distance of 2.5 million light years, it is the most distant object visible to the unaided eye. To the north of M31 is the constellation of Cassiopeia which draws an 'M' in our sky. It is found in the most northerly part of the Milky Way.
Uranus' new siblings:
Uranus has two new satellites, bringing the total to 17. With an estimated diameter of 60 km, the satellites have provisionally been named U1 and U2.
Serge Florens, Secretary