November 3, 1898] 



NA rURE 



13 



sufificient to allow that well-known indefatigable minor 

 planet-orbit calculator, Herr H. Rerberich, to compute its 

 orbit. The accompanying chart (Fig. i) shows the path of 

 the planet in the sky from .\ugust 14 to December 31. The 

 Roman figures in the chart from VIII to I correspond 

 to the dates August 14, September t, October I, November 

 I, 15, December i, 15, 31, of the present year. 



Now comes the astonishing result of Herr Berberich's 

 computation. The planet was not one of those small 

 bodies which revolve round the sun between Mars and 

 Jupiter, but was an entirely new body, its path lying for 

 the main part within that of Mars. 



Here are the elements of the planet's orbit as given by 

 the calculations. It must be mentioned, however, that 

 these elements cannot be considered as final, since more 

 observations, extending over a much longer period, are 

 required to ultimately establish the true elements. These 

 elements, however, will not deviate very much from those 

 given below. 



Epoch 1S98, August 31-5, Berlin Mean Time. 



Mean anomaly ... ... 220 14 37 



Perihelion distance from 



ascending node ... 17S 28 26 '2 

 Longitude of ascending 



node 303 48 53-0 



Inclination of orbit to 



that of the earth ... 11 6 57 'i 

 Eccentricity ... ... 13 13 3'8 



Mean daily movement, 20io'''l3l 



Period of revolution round the sun, 645 days. 



Taking the mean distance of the earth from the sun 

 as unity, the new planet at perihelion approaches the sun 

 to within fl2 of these units, and when furthest away 

 is distant 179 of these units. These values in the case 

 of Mars are r38 and r67 respectively. We thus see 

 that we can now no longer look upon Mars as our nearest 

 neighbour (excepting, of course, our moon), for the mean 

 distance of Mars from the sun amounts to I '52, while 

 that of the new planet is v\b. 



The accompanying diagram (Fig. 2) shows the relation 

 of the new planet's orbit relative to that of Mars. 



Fig 2,— Comparison of orbits of M 



planet D Q. 



Assuming that Berberich's elements are correct, it is 

 interesting to inquire into some of the relations which 

 this orbit presents. Mr. Crommelin, to whom we are 

 indebted for the above diagram, has considered such 

 relations in his article in The Obserz'atory (October, p. 

 372). A synodic period being two successive conjunctions 

 with the sun as seen from the earth, this in the case of 

 the new planet is 2-3o692 years. We thus see that three 



NO. 15 14, VOL. 59] 



synodic periods equal nearly seven years, so that after 

 this period oppositions are repeated in nearly the same 

 regions of the orbit. A closer approximation would be 

 obtained if thirteen synodic periods, which extend over 

 29'99 years, were considered. As regards the time when 

 the planet comes into opposition — a point of great 

 importance, especially in the case of this planet — Mr. 

 Crommelin tells us that, unfortunately, "an opposition 

 under the most favourable circumstances took place in 

 January 1894," and that we shall have to wait now until 

 January 1924 until another equally favourable one occurs. 

 In the years 1900 and 19 17, only moderately favourable 

 oppositions will occur, the planet in November of the 

 former year then being of magnitude 8 or 9. 



The close approach of this planet to the earth at times 

 of favourable opposition will give us excellent oppor- 

 tunities of determining, more accurately than was possible 

 before, the parallax of the sun — or, in other words, the 

 distance of the sun from the earth. 



The importance of a correct value of this quantity is 

 very great, when it is considered that all measurements 

 of distance in our solar system are based on it. Just as 

 the foot is taken as a unit in measuring the side of a 

 room, or a mile in measuring a strip of country, so 

 astronomers adopt the mean distance of the earth from 

 the sun as the unit in measuring the distance of 

 Jupiter or Mars. A more accurate value of the standard 

 of measurement for the solar system is, therefore, of the 

 highest importance. 



Since the new planet when nearest to and furthest from 

 us will vary from the sixth to the twelfth magnitude, 

 several useful photometric problems may be attacked. 

 Thus, as Prof Pickering suggests, the approximate 

 diameter may be determined by comparing it with those 

 of the brighter minor planets and satellites, on the 

 assumption that the reflecting power is the same. 



Again, the well-known law that light varies inversely 

 as the square of the distance might be tested, as the 

 planet's distance from the earth varies very considerably. 

 At the same time, it could be determined whether there 

 exists in the solar system any medium capable of 

 absorbing light. 



Let us now consider whether the law of Bode holds 

 good for the presence of this new planet. 



We give below a table showing a comparison between 

 the true mean distances and those calculated by Bode's 

 law. 



In the above table the column headed "Bode "gives 

 the distance according to the law of Bode, while the 

 following column, that headed " Dift'.," represents the 

 difference between the true mean distance, as given in 

 the second column, and that calculated after Bode's law. 



A glance at this will show that the distance of the new 

 planet does not fall into line at all, but, like Neptune, is 

 an exception to the law. 



Indeed, for the new planet, Bode's law does not even 

 suggest a number, as there is no break between the 

 distance accorded to our Earth and that of Mars. If we 

 assume the law of Bode as mainly correct, then we must 

 look upon the new planet as one of the minor planets 

 gone somewhat astray. 



