ASTRONOMICAL NOTES FOR MARCH.

Lyttelton Times, Volume CXV, Issue 16487, 28 February 1914, Page 10

ASTRONOMICAL NOTES FOR MARCH.

Mars and Saturn still remain visible in the evenings, but they are both passing away rapidly to the west where they set rather early, and no other planets are yet coming into the evening sky from the east. Both these planets passed through their stationary points on February 12, and are now finishing their loops and moving eastward again through the stars. In the case of Mars the apparent motion during March is about seven degrees, ' which is quite large enough to, be perceived even by the naked, eye observer, especially as the .planet moves from left to right of a third magnitude star, Epsilon Geminorum. Saturn’s motion is very much less, not cpiite two degrees during March, and his position to the east of the Hyades does not change by an amount that anyone is likely to notice by mere naked eye observation. Mars sets on March 1, at 0.12 a.m., and on March 31 at 10.58 p.m. Saturn sets on these two dates at 10.46 p.m., and at 8.54 p.m., respectively. Jupiter has already made his appearance in the morning sky, but even by the end of this month he does not rise before 1.30 a.m., so the time for observing him has scarcely arrived yet. There seems to be a singular lack of opportunities for local observers during March. An eclipse of the moon on March 12 is just exactly invisible in New Zealand as the moon leaves the penumbra at 6.15 p.m., the very instant at which she rises here. The constellation of Cancer, the Crab, will be found upon the meridian about 8 to 9 p.m., and to the east of it is the Lion, easily recognised by tho principal stars arranging themselves in the form of a mark of interrogation but upside down in this latitude. Farthe; east is the Virgin, which resembles i letter Y rather than any other shape. Due south from the Virgin almost in the direction of the Southern Cross, there is a group of four bright stars supposed to represent . the head, ,v. tail and two wings of a bird, and this is the constellation of Corvusj the Raven, The two southern stars point eastward to a third magnitude star, Gamma Hydrae, having a fifth magnitude star, Psi Hydrae, two degrees west' of it, but otherwise rather isolated. On the side of Gamma opposite to Psi is a very interesting variable star,, R Hydrae, which at the date of writing V growing brighter at a rapid rate and is worth a little attention just now. It has just reached the sixth magnitude, so that it is dimly visible to the naked eye and easily seen with field glasses, but it is fairly safe to pro- x diet that bv the end of March or in April it will be about the fourth magnitude. At its minimum last September it was below the ninth magnir tude, so it has already risen more than three magnitudes. During March it may be expected to change from a telescopic star to a naked eye object, thus furnishing an illustration of the peculiarities of a variable star. , It is worth noting that a small group of spots passed across the sun’s disc at the beginning of. February, thus interrupting the long period of spotlessness that has lasted for eight or nine months. The return of solar activity was expected in 1913, and is already one year behind prediction, so it seems reasonable to look for a more frequent supply of spots to begin at any time now.

There was some rather' remarkable discussion on the subject of sunspots' at the meeting cf the Royal Astronomical Society on December 12. Mr Maunder began it with a communication on the distribution of sunspots, and Professor Turner followed with s paper which might have been called speculative had anyone with less knowledge of the subject been the autho: of it. Professor Turner has several times before analysed the eleven-year .cycle of sunspot frequency; and found it to be apparently a blend of other periods of different lengths, but in this paper he stated that- several of the periods he had traced through the records of sunspot activity axe not permanent. He had found unexpected interruptions of the periods occurring quite suddenly in the years 1767, 1800, 1833, 1866 and 1900. Now these dates, he pointed out, are significant; they are the dates of the Leonid meteors.

The Leonids, it should be explained, are a swarm of meteors which move round the sun in a period of thirtythree years, and the earth passes through their orbit about November 13 every year. Usually a few meteors are to ho 6een at that time in any year, but these are only stragglers, for the most • of them seem to keep together in a swarm, which can only bo encountered once during the whole period of thirty-three years. So far Professor Turner had made no assumptions or speculations, but in accounting for the effects of the Leo nid swarm upon the 6un ho had to 6up pose that there is a companion swarm passing much nearer to tho sun than the main swarm, whose perihelion distance is not much less than that of tho earth. Now the point to he emphasised is that if the hypothetical swarm grazes the visible surface of the sun and has a period of eleven years, its aphelion distance must be about equal to the distance of the 'planet Saturn. And it is a fact that the main swarm of the Leonids passes close to that planet, and therefore Professor Turner considers there is reason for t theory that the second swarm was brought into existence by the collision of Saturn with the original swarm at reneated intervals. The reason' for r. -rting that such a collision if it once happened must he repeated is that eight times the period of the meteors is equal to nine times the period < or Saturn, the product in each case being 265 years, so a collision once about would be repeated at intervals of that duration. _ • Rrnfaesor Turner, in concluding \ ms

address, made his point by quoting from the sunspot records to show that remarkable outbursts of largo spots bid occurred at intervals exactly 260 years apart. Moreover, there are certain other facts that can be called as evidence, such as an unexplained irregularity in the motion of Saturn and some apparent discrepancies in the values of the sun’s rotation deduced from the observations of the sunspots •t different times. One of the scientific magazines states that Professor Turner began his paper in an atmosphere of incredulity, but finished ’t amidst a burst of applause. The report of the proceedings quotes tho president as having described tho paper as provocative and interesting.