The Birmingham age-herald., 1920-02-01

cur on the nights of February ,, 3, [, Il. 14, 15 and 26.
 saturn for the first time this year appears among the stars of our eve ming map where it is seen moving slowly northward and westward, al- most in the exact center of the con- stellation Leo. This is now beauti- fu1 object In the telescope. Tine rings are however, now seen nearly edge wise, so that they appear very narrow. They will widen a very little until April IT. when they will be seen to narrow rapidly until they completely disappear in moderate sized telescopes in November. We are now looking on
 their southern surface; from November
 until the end of the year the earth will
 be above the plane of the rings and
 we will then view their northern sur
 face.
 ULTRA-NUPTUNIAN PLANET
 It was in the year 1S46 that the ex
 istence of a new planet was announced
 from a purely mathematical analysis.
 and this has ever been justly regarded
 as a great triumph in celestia me
 chanics. As nearly everyone knows,
 that there was d great, unseen world
 moving in an orbit far greater than
 that of Uranus, was rendered certain
 hy study of the latter body along it's
 path. By the year 1S45 Uranus had
 gotten 1s3 seconds ahead of where it
 should have been in the sky evidently
 it must be disturbed in it's motion by
 the pull of some world whose pull had
 not already been allowed for, and it
 was from an intricate mathematical
 study of the varing perturbations that
 the exact position of the disturbing
 body in the sky could be stated. The
 new body was looked for on the night
 of September 23. 1S46. and within half
 an hour after the search began it was
 found in exact accordance with the
 rrediction.
 But during the 75 years which elapsed since the discovery of Nep- tune. in which time Uranus has gone almost completely around it's orbit, lt has been found to be still apparently slightly disturbed in it's motion. Some 1 times it is slightly ahead of where 1t should be in the sky and some times 1 behind though the displacements are very much less than before the ac- I tion of Neptune was allowed for. Thus
 at no part of it's great path is the planet much more than five seconds ] from it's predicted position, very
 much smaller quantity than the l3S ] seconds with which Leverrier, the dls- | coverer of Neptune. had to deal.
 The smallness of this disturbance IS
 doubtless due to the great distance 1 away of the disturbing planet but 1t 1 makes the exact prediction of the di- | rection of the new body very difficult For the measures of the position Of 1 Uranus cannot be made with perfect l accuracy at the telescope. and the un-
 avoidable errors of observation make
 the errors of theory somewhat uncer-
 tain.
 Figure 2 shows the errors as they are determined from 1S45 to 1905. Were
 the observations perfectly accurate, all
 of the dots would lie exactly on smooth curve. It will be noticed that in 1895 the planet was 5.2 seconds west of the place 1t should nave occupieu in the sky
 | Several solutions of the problem have been carried through. though the results are somewhat uncertain. one of the latest indicates that the new body must move in great orbit nearly 4,00o,000,000 miles from the sun, and that it occupies 2S3 years in making the circuit of the heavens. Its mass is about six times that of he earth so that it is much smaller than any of it's four neighboring planets, According to this solution. the new planet is now in the western borders of the constellation Gemini. in excel lent position for observation.
 SEARCHING FOR NEW PLANET At the great distance of the sup posed body from the sun, it will re- ceive but one seventeen-hundredt l part as much sunlight as the earth does. In fact as seen from this dls- tant world the sun would appear as point of light, an intensely brilliant star But though the sun would ap- | rear to have no disc. 1t would be near iy 400 times as bright as the full l moon. The inhabitants of thiss world, if there are any there. would by no means dwell in darkness
 The unknown body is also very far from the earth. When we consider its | small mass and also it's great distance 10th from the sun and from us we see at once that even when viewed under the most favorable conditions Il 1 it must appear very faint. In fact, Il II is believed that when discovered II II will shine only as star of the l2 tc H the Is magnitude, and thus only be Il visible in the larger telescopes Il Unfortunately, We have no complete H l charts showing nearly so faint star. H as this There has been published { II great survey of some S40.000 stars, bu H these only extend to the 95 magnitude II Even in the course ot the next hal Il century. when the great Astrographl' H Catalogue may be completed, this VII III only show stars in general down tC II the twelfth magnitude or even no Il quite so faint.
 Il Therefore the only method of searei If is to take long exposure photograph II of the region of the sky in which tho Il new planet is expected to be found Il and then after a suitable intervals II probably of few weeks. to photo Il graph the region again. By comparing II the very faintest points of light 0, II similar plates it can then be determine H whether one of these has moved slight Il ly. If so. the moving body cannot b. Il a star, and may be the new planet III Anyone who has seen long -expose' HI photogra phic plate of this region HI which is in the Milky Way, with hun HI dreds of thousands of stars on it, cal HI im zine how laborios=5 the search vii HI be. even by photography. Nisually. i HI would be practically impossible Ye HI on any day the announcement of tn HI new discovery may be made, and tn HI limits of our solar system greatly ex HI tended. ERIC DOOLITTI.E. HI TIT, T. xr IT ct nXXrAr